2024-03-28T19:11:08Zhttps://www.repo.uni-hannover.de/oai/requestoai:www.repo.uni-hannover.de:123456789/2692022-12-13T15:12:26Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2016-03-04T11:42:41Z
urn:hdl:123456789/269
Risk assessment for slope monitoring
Zhang, Yin
Neumann, Ingo
geodetic monitoring
hypothesis testing
utility theory
cost functions
decision making
One main goal of geodetic deformation monitoring and analysis is minimizing the risk of unexpected collapses of artificial objects and geologic hazards. Nowadays, the methodology in applied geodesy and mathematically founded decisions are usually based on probabilities and significance levels but not on the risk (consequences or costs) itself. In this study, a new concept which is based on the utility theory is introduced to the current methodology. It allows the consideration of consequences or costs for geodetic decision making in order to meet the real requirements. In this case, possible decisions are evaluated with cost functions for type I and II errors. Finally, the decision leading to the minimum costs or consequences is chosen as the most beneficial one. This procedure allows also identifying the most beneficial additional measurements to reduce the risk of an individual monitoring process. In the last part, the theoretical concept is applied to an example in slope monitoring.
2016-03-04T11:42:41Z
2016-03-04T11:42:41Z
2013-08
Article
Text
Zhang, Yin; Neumann, Ingo: Risk assessment for slope monitoring. In: Journal of Applied Geodesy 7 (2013), Nr. 3, S. 159-171. DOI: http://dx.doi.org/10.1515/jag-2012-0036
http://www.repo.uni-hannover.de/handle/123456789/269
http://dx.doi.org/10.15488/247
eng
Journal of Applied Geodesy 7 (2013), Nr. 3
1862-9024
1862-9016
http://dx.doi.org/10.1515/jag-2012-0036
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
Berlin : Walter de Gruyter
oai:www.repo.uni-hannover.de:123456789/2702022-12-13T15:12:26Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2016-03-04T11:42:42Z
urn:hdl:123456789/270
On the detection of systematic errors in terrestrial laser scanning data
Wang, Jin
Kutterer, Hansjörg
Fang, Xing
Terrestrial laser scanning
systematic errors
iterative closest point
structural monitoring
quadratic form estimation
Gauss–Helmert model
Quality descriptions are parts of the key tasks of geodetic data processing. Systematic errors should be detected and avoided in order to insure the high quality standards required by structural monitoring. In this study, the iterative closest point (ICP) method was invested to detect systematic errors in two overlapping data sets. There are three steps to process the systematic errors: firstly, one of the data sets was transformed to a reference system by the introduction of the Gauss–Helmert (GH) model. Secondly, quadratic form estimation and segmentation methods are proposed to guarantee the overlapping data sets. Thirdly, the ICP method was employed for a finer registration and detecting the systematic errors. A case study was casted in which a dam surface in Germany was scanned by terrestrial laser scanning (TLS) technology. The results indicated that with the conjugation of ICP algorithm the accuracy of the data sets was improved approximately by 1.6 mm.
2016-03-04T11:42:42Z
2016-03-04T11:42:42Z
2012-11
Article
Text
Wang, Jin; Kutterer, Hansjoerg; Fang, Xing: On the detection of systematic errors in terrestrial laser scanning data. In: Journal of Applied Geodesy 6 (2012), Nr. 3-4, S. 187-192. DOI: http://dx.doi.org/10.1515/jag-2012-0025
http://www.repo.uni-hannover.de/handle/123456789/270
http://dx.doi.org/10.15488/248
eng
Journal of Applied Geodesy 6 (2012), Nr. 3-4
1862-9024
1862-9016
http://dx.doi.org/10.1515/jag-2012-0025
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
Berlin : Walter de Gruyter
oai:www.repo.uni-hannover.de:123456789/2712022-12-13T15:12:26Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2016-03-04T11:42:42Z
urn:hdl:123456789/271
Direct geo-referencing of a static terrestrial laser scanner
Paffenholz, Jens-André
Alkhatib, Hamza
Kutterer, Hansjörg
Terrestrial laser scanning
light detection and ranging
global navigation satellite system
geo-referencing
extended Kalman filter
This paper describes an adaptive extended Kalman filter (AEKF) approach for geo-referencing tasks for a multi-sensor system (MSS). The MSS is a sensor fusion of a phase-measuring terrestrial laser scanner (TLS) with navigation sensors such as Global Navigation Satellite System (GNSS) equipment and inclinometers. The position and orientation of the MSS are the main parameters which are constant on a station and will be derived by a Kalman filtering process. Hence, the orientation of a TLS/MSS can be done without any demand for other artificial targets in the scanning area. However, using inclinometer measurements the spatial rotation angles about the X- and Y-axis of the fixed MSS station can be estimated by the AEKF. This makes it possible to determine all six degrees of freedom of the transformation from a sensor-defined to a global coordinate system. The paper gives a detailed discussion of the strategy used for the direct geo-referencing. The AEKF for the transformation parameters estimation is presented with focus on the modelling of the MSS motion. The usefulness of the suggested approach will be demonstrated using practical investigations.
2016-03-04T11:42:42Z
2016-03-04T11:42:42Z
2010-01
Article
Text
Paffenholz, Jens-André; Alkhatib, Hamza; Kutterer, Hansjörg: Direct geo-referencing of a static terrestrial laser scanner. In: Journal of Applied Geodesy 4 (2010), Nr. 3, S. 115-126. DOI: http://dx.doi.org/10.1515/jag.2010.011
http://www.repo.uni-hannover.de/handle/123456789/271
http://dx.doi.org/10.15488/249
eng
Journal of Applied Geodesy 4 (2010), Nr. 3
1862-9024
1862-9016
http://dx.doi.org/10.1515/jag.2010.011
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
Berlin : Walter de Gruyter
oai:www.repo.uni-hannover.de:123456789/2722022-12-13T15:12:26Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2016-03-04T11:42:42Z
urn:hdl:123456789/272
Validation of a kinematic laserscanning system
Vennegeerts, Harald
Martin, Jens
Becker, Matthias
Kutterer, Hansjörg
mobile mapping
kinematic laserscanning
terrestrial lidar
synchronization
The increasing data rate of actual laser scanners qualifies these sensors for kinematic applications. In case of surveying static environments the scanner can be integrated into a moving platform system. Therefore two main tasks are outstanding. Position and orientation of the platform have to be registered throughout a freely driven trajectory. The second challenge is to synchronize the scanned spatial data with the time scale of the positioning unit. This paper presents the specification of a mobile mapping system using a phase-based laser scanner with a hybrid INS (Inertial Navigation System)/GPS solution. Among a description of the system structure it includes a software-based method to synchronize the scanned profiles with the trajectory. No extra hardware unit for time registration of scanned profiles is required. After all a spatial comparison of independently observed control points allows the assessment of the system performance.
2016-03-04T11:42:42Z
2016-03-04T11:42:42Z
2008-01
Article
Text
Vennegeerts, Harald; Martin, Jens; Becker, Matthias; Kutterer, Hansjörg: Validation of a kinematic laserscanning system. In: Journal of Applied Geodesy 2 (2008), Nr. 2, S. 79-84. DOI: http://dx.doi.org/10.1515/JAG.2008.009
http://www.repo.uni-hannover.de/handle/123456789/272
http://dx.doi.org/10.15488/250
eng
Journal of Applied Geodesy 2 (2008), Nr. 2
1862-9024
1862-9016
http://dx.doi.org/10.1515/JAG.2008.009
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
Berlin : Walter de Gruyter
oai:www.repo.uni-hannover.de:123456789/7112023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:29Z
urn:hdl:123456789/711
Sub-camera calibration of a Penta-camera
Jacobsen, Karsten
Gerke, M.
Skaloud, J.
Colomina, I.
Bundle block adjustment
Penta camera
Self calibration
Calibration
Errors
Systematic errors
Boresight calibrations
Bundle block adjustments
Camera calibration
Exterior orientation
Geometric relations
Self calibration
Strongly connected
Tangential effects
Cameras
Penta cameras consisting of a nadir and four inclined cameras are becoming more and more popular, having the advantage of imaging also facades in built up areas from four directions. Such system cameras require a boresight calibration of the geometric relation of the cameras to each other, but also a calibration of the sub-cameras. Based on data sets of the ISPRS/EuroSDR benchmark for multi platform photogrammetry the inner orientation of the used IGI Penta DigiCAM has been analyzed. The required image coordinates of the blocks Dortmund and Zeche Zollern have been determined by Pix4Dmapper and have been independently adjusted and analyzed by program system BLUH. With 4.1 million image points in 314 images respectively 3.9 million image points in 248 images a dense matching was provided by Pix4Dmapper. With up to 19 respectively 29 images per object point the images are well connected, nevertheless the high number of images per object point are concentrated to the block centres while the inclined images outside the block centre are satisfying but not very strongly connected. This leads to very high values for the Student test (T-test) of the finally used additional parameters or in other words, additional parameters are highly significant. The estimated radial symmetric distortion of the nadir sub-camera corresponds to the laboratory calibration of IGI, but there are still radial symmetric distortions also for the inclined cameras with a size exceeding 5μm even if mentioned as negligible based on the laboratory calibration. Radial and tangential effects of the image corners are limited but still available. Remarkable angular affine systematic image errors can be seen especially in the block Zeche Zollern. Such deformations are unusual for digital matrix cameras, but it can be caused by the correlation between inner and exterior orientation if only parallel flight lines are used. With exception of the angular affinity the systematic image errors for corresponding cameras of both blocks have the same trend, but as usual for block adjustments with self calibration, they still show significant differences. Based on the very high number of image points the remaining image residuals can be safely determined by overlaying and averaging the image residuals corresponding to their image coordinates. The size of the systematic image errors, not covered by the used additional parameters, is in the range of a square mean of 0.1 pixels corresponding to 0.6μm. They are not the same for both blocks, but show some similarities for corresponding cameras. In general the bundle block adjustment with a satisfying set of additional parameters, checked by remaining systematic errors, is required for use of the whole geometric potential of the penta camera. Especially for object points on facades, often only in two images and taken with a limited base length, the correct handling of systematic image errors is important. At least in the analyzed data sets the self calibration of sub-cameras by bundle block adjustment suffers from the correlation of the inner to the exterior calibration due to missing crossing flight directions. As usual, the systematic image errors differ from block to block even without the influence of the correlation to the exterior orientation.
2016-11-21T07:54:29Z
2016-11-21T07:54:29Z
2016
Article
Text
Jacobsen, K.; Gerke, M.: Sub-camera calibration of a Penta-camera. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 40 (2016), Nr. 3W4, S. 35-40. DOI: http://dx.doi.org/10.5194/isprsarchives-XL-3-W4-35-2016
http://www.repo.uni-hannover.de/handle/123456789/711
http://dx.doi.org/10.15488/687
eng
EuroCOW 2016, the European Calibration and Orientation Workshop
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XL-3/W4
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XL-3-W4-35-2016
https://doi.org/10.5194/isprsarchives-xl-3-w4-35-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7122022-12-02T16:17:36Zcom_123456789_1col_123456789_3doc-type:BookPartdoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:32Z
urn:hdl:123456789/712
Global bundle adjustment with variable orientation point distance for precise mars express orbit reconstruction
Bostelmann, Jonas
Heipke, Christian
Halounova, L.
Šafář, V.
Jiang, J.
Olešovská, H.
Dvořáček, P.
Holland, D.
Seredovich, V.A.
Muller, J.-P.
Pattabhi Rama Rao, E.
Veenendaal, B.
Mu, L.
Zlatanova, S.
Oberst, J.
Yang, C.P.
BAN, Y.
Stylianidis, S.
Voženílek, V.
Vondráková, A.
Gartner, G.
Remondino, F.
Doytsher, Y.
Percivall, G.
Schreier, G.
Dowman, I.
Streilein, A.
Ernst, J.
Bundle adjustment
HRSC
Mapping
Mars
Orbit modeling
Planetary
Cameras
Mapping
Martian surface analysis
Orbits
Photogrammetry
Remote sensing
Trajectories
Bundle adjustments
HRSC
Mars
Orbit modeling
Planetary
Stereo image processing
The photogrammetric bundle adjustment of line scanner image data requires a precise description of the time-dependent image orientation. For this task exterior orientation parameters of discrete points are used to model position and viewing direction of a camera trajectory via polynomials. This paper investigates the influence of the distance between these orientation points on the quality of trajectory modeling. A new method adapts the distance along the trajectory to the available image information. Compared to a constant distance as used previously, a better reconstruction of the exterior orientation is possible, especially when image quality changes within a strip. In our research we use image strips of the High Resolution Stereo Camera (HRSC), taken to map the Martian surface. Several experiments on the global image data set have been carried out to investigate how the bundle adjustment improves the image orientation, if the new method is employed. For evaluation the forward intersection errors of 3D points derived from HRSC images, as well as their remaining height differences to the MOLA DTM are used. In 13.5 % (515 of 3,828) of the image strips, taken during this ongoing mission over the last 12 years, high frequency image distortions were found. Bundle adjustment with a constant orientation point distance was able to reconstruct the orbit in 239 (46.4 %) cases. A variable orientation point distance increased this number to 507 (98.6 %).
2016-11-21T07:54:32Z
2016-11-21T07:54:32Z
2016
BookPart
Text
Bostelmann, J.; Heipke, C.: Global bundle adjustment with variable orientation point distance for precise mars express orbit reconstruction. In: Halounova, I. et al. (Eds.): XXIII ISPRS Congress, Commission IV. Katlenburg-Lindau : Copernicus Publications, 2016 (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 41-B4), S. 361-368. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B4-361-2016
http://www.repo.uni-hannover.de/handle/123456789/712
http://dx.doi.org/10.15488/688
eng
XXIII ISPRS Congress, Commission IV
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 41-B4
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B4-361-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Katlenburg-Lindau : Copernicus Publications
oai:www.repo.uni-hannover.de:123456789/7132023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:33Z
urn:hdl:123456789/713
Integration of a generalised building model into the pose estimation of UAS images
Unger, Jakob
Rottensteiner, Franz
Heipke, Christian
Halounova, L.
Šafář, V.
Toth, C.K.
Karas, J.
Huadong, G.
Haala, N.
Habib, A.
Reinartz, P.
Tang, X.
Li, J.
Armenakis, C.
Grenzdörffer, G.
le Roux, P.
Stylianidis, S.
Blasi, R.
Menard, M.
Dufourmount, H.
Li, Z.
Building model
Hybrid bundle adjustment
Pose estimation
UAS
Unmanned aerial system
Computer vision
Remote sensing
Unmanned aerial vehicles (UAV)
Building model
Bundle adjustments
Distance criterion
Image orientation
Object coordinates
Pose estimation
Real image sequences
Unmanned aerial systems
A hybrid bundle adjustment is presented that allows for the integration of a generalised building model into the pose estimation of image sequences. These images are captured by an Unmanned Aerial System (UAS) equipped with a camera flying in between the buildings. The relation between the building model and the images is described by distances between the object coordinates of the tie points and building model planes. Relations are found by a simple 3D distance criterion and are modelled as fictitious observations in a Gauss-Markov adjustment. The coordinates of model vertices are part of the adjustment as directly observed unknowns which allows for changes in the model. Results of first experiments using a synthetic and a real image sequence demonstrate improvements of the image orientation in comparison to an adjustment without the building model, but also reveal limitations of the current state of the method.
2016-11-21T07:54:33Z
2016-11-21T07:54:33Z
2016
Article
Text
Unger, J.; Rottensteiner, F.; Heipke, C.: Integration of a generalised building model into the pose estimation of UAS images. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 1057-1064. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B1-1057-2016
http://www.repo.uni-hannover.de/handle/123456789/713
http://dx.doi.org/10.15488/689
eng
XXIII ISPRS Congress, Commission I
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B1
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B1-1057-2016
https://doi.org/10.5194/isprsarchives-xli-b1-1057-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7142023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:33Z
urn:hdl:123456789/714
3D feature point extraction from LiDAR data using a neural network
Feng, Yu
Schlichting, Alexander
Brenner, Claus
Halounova, L.
Šafář, V.
Toth, C.K.
Karas, J.
Huadong, G.
Haala, N.
Habib, A.
Reinartz, P.
Tang, X.
Li, J.
Armenakis, C.
Grenzdörffer, G.
le Roux, P.
Stylianidis, S.
Blasi, R.
Menard, M.
Dufourmount, H.
Li, Z.
3D feature points extraction
LiDAR
Mobile mapping system
Neural network
Backpropagation
Backpropagation algorithms
Edge detection
Extraction
Image matching
Neural networks
Poles
Remote sensing
Vehicles
Autonomous driving
Corner detector
Feature point extraction
Feature points extraction
Lidar point clouds
Accurate positioning of vehicles plays an important role in autonomous driving. In our previous research on landmark-based positioning, poles were extracted both from reference data and online sensor data, which were then matched to improve the positioning accuracy of the vehicles. However, there are environments which contain only a limited number of poles. 3D feature points are one of the proper alternatives to be used as landmarks. They can be assumed to be present in the environment, independent of certain object classes. To match the LiDAR data online to another LiDAR derived reference dataset, the extraction of 3D feature points is an essential step. In this paper, we address the problem of 3D feature point extraction from LiDAR datasets. Instead of hand-crafting a 3D feature point extractor, we propose to train it using a neural network. In this approach, a set of candidates for the 3D feature points is firstly detected by the Shi-Tomasi corner detector on the range images of the LiDAR point cloud. Using a back propagation algorithm for the training, the artificial neural network is capable of predicting feature points from these corner candidates. The training considers not only the shape of each corner candidate on 2D range images, but also their 3D features such as the curvature value and surface normal value in z axis, which are calculated directly based on the LiDAR point cloud. Subsequently the extracted feature points on the 2D range images are retrieved in the 3D scene. The 3D feature points extracted by this approach are generally distinctive in the 3D space. Our test shows that the proposed method is capable of providing a sufficient number of repeatable 3D feature points for the matching task. The feature points extracted by this approach have great potential to be used as landmarks for a better localization of vehicles.
2016-11-21T07:54:33Z
2016-11-21T07:54:33Z
2016
Article
Text
Feng, Y.; Schlichting, A.; Brenner, C.: 3D feature point extraction from LiDAR data using a neural network. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 563-569. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B1-563-2016
http://www.repo.uni-hannover.de/handle/123456789/714
http://dx.doi.org/10.15488/690
eng
XXIII ISPRS Congress, Commission I
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B1
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B1-563-2016
https://doi.org/10.5194/isprsarchives-xli-b1-563-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7152022-12-02T16:17:36Zcom_123456789_1col_123456789_3doc-type:BookPartdoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:34Z
urn:hdl:123456789/715
Vehicle localization by lidar point correlation improved by change detection
Schlichting, Alexander
Brenner, Claus
Halounova, L.
Šafář, V.
Toth, C.K.
Karas, J.
Huadong, G.
Haala, N.
Habib, A.
Reinartz, P.
Tang, X.
Li, J.
Armenakis, C.
Grenzdörffer, G.
le Roux, P.
Stylianidis, S.
Blasi, R.
Menard, M.
Dufourmount, H.
Li, Z.
Change detection
Classification
Correlation
LiDAR
Localization
Mobile mapping
Chemical detection
Classification (of information)
Correlation methods
Decision trees
Image matching
Mapping
Optical radar
Remote sensing
Signal detection
Vehicles
Change detection
Change detection algorithms
Classification algorithm
LiDAR sensors are proven sensors for accurate vehicle localization. Instead of detecting and matching features in the LiDAR data, we want to use the entire information provided by the scanners. As dynamic objects, like cars, pedestrians or even construction sites could lead to wrong localization results, we use a change detection algorithm to detect these objects in the reference data. If an object occurs in a certain number of measurements at the same position, we mark it and every containing point as static. In the next step, we merge the data of the single measurement epochs to one reference dataset, whereby we only use static points. Further, we also use a classification algorithm to detect trees. For the online localization of the vehicle, we use simulated data of a vertical aligned automotive LiDAR sensor. As we only want to use static objects in this case as well, we use a random forest classifier to detect dynamic scan points online. Since the automotive data is derived from the LiDAR Mobile Mapping System, we are able to use the labelled objects from the reference data generation step to create the training data and further to detect dynamic objects online. The localization then can be done by a point to image correlation method using only static objects. We achieved a localization standard deviation of about 5 cm (position) and 0.06° (heading), and were able to successfully localize the vehicle in about 93 % of the cases along a trajectory of 13 km in Hannover, Germany.
2016-11-21T07:54:34Z
2016-11-21T07:54:34Z
2016
BookPart
Text
Schlichting, A.; Brenner, C.: Vehicle localization by lidar point correlation improved by change detection. In: Halounova, L.; Šafář, V.; Toth, C.K. et al. (Eds.): XXIII ISPRS Congress, Commission I. Göttingen : Copernicus GmbH, 2016 (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 41-B1), S. 703-710. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B1-703-2016
http://www.repo.uni-hannover.de/handle/123456789/715
http://dx.doi.org/10.15488/691
eng
XXIII ISPRS Congress, Commission I
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 41-B1
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B1-703-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7162023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:39Z
urn:hdl:123456789/716
Analysis and correction of systematic height model errors
Jacobsen, Karsten
Halounova, L.
Šafář, V.
Toth, C.K.
Karas, J.
Huadong, G.
Haala, N.
Habib, A.
Reinartz, P.
Tang, X.
Li, J.
Armenakis, C.
Grenzdörffer, G.
le Roux, P.
Stylianidis, S.
Blasi, R.
Menard, M.
Dufourmount, H.
Li, Z.
DSM/DTM
Optical space images
Orientation
Satellite jitter
Systematic error
Aluminum
Calibration
Crystal orientation
Deformation
Errors
Remote sensing
Rock mechanics
Satellites
Tracking radar
Affine transformations
Digital surface models
DSM/DTM
Optical satellite images
Orientation information
The geometry of digital height models (DHM) determined with optical satellite stereo combinations depends upon the image orientation, influenced by the satellite camera, the system calibration and attitude registration. As standard these days the image orientation is available in form of rational polynomial coefficients (RPC). Usually a bias correction of the RPC based on ground control points is required. In most cases the bias correction requires affine transformation, sometimes only shifts, in image or object space. For some satellites and some cases, as caused by small base length, such an image orientation does not lead to the possible accuracy of height models. As reported e.g. by Yong-hua et al. 2015 and Zhang et al. 2015, especially the Chinese stereo satellite ZiYuan-3 (ZY-3) has a limited calibration accuracy and just an attitude recording of 4 Hz which may not be satisfying. Zhang et al. 2015 tried to improve the attitude based on the color sensor bands of ZY-3, but the color images are not always available as also detailed satellite orientation information. There is a tendency of systematic deformation at a Pléiades tri-stereo combination with small base length. The small base length enlarges small systematic errors to object space. But also in some other satellite stereo combinations systematic height model errors have been detected. The largest influence is the not satisfying leveling of height models, but also low frequency height deformations can be seen. A tilt of the DHM by theory can be eliminated by ground control points (GCP), but often the GCP accuracy and distribution is not optimal, not allowing a correct leveling of the height model. In addition a model deformation at GCP locations may lead to not optimal DHM leveling. Supported by reference height models better accuracy has been reached. As reference height model the Shuttle Radar Topography Mission (SRTM) digital surface model (DSM) or the new AW3D30 DSM, based on ALOS PRISM images, are satisfying. They allow the leveling and correction of low frequency height errors and lead to satisfying correction of the DSM based on optical satellite images. The potential of DHM generation, influence of systematic model deformation and possibilities of improvement has been investigated.
2016-11-21T07:54:39Z
2016-11-21T07:54:39Z
2016
Article
Text
Jacobsen, K.: Analysis and correction of systematic height model errors. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 333-339. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B1-333-2016
http://www.repo.uni-hannover.de/handle/123456789/716
http://dx.doi.org/10.15488/692
eng
XXIII ISPRS Congress, Commission I
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B1
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B1-333-2016
https://doi.org/10.5194/isprsarchives-xli-b1-333-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7172023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:39Z
urn:hdl:123456789/717
The status of topographic mapping in the world a UNGGIM - ISPRS project 2012-2015
Konecny, G.
Breitkopf, Uwe
Radtke, A.
Halounova, L.
Yang, C.P.
Remondino, F.
Zlatanova, S.
Muller, J.P.
Veenendaal, B.
Mu, L.
Oberst, J.
Ernst, J.
Jiang, J.
Voženílek, V.
Percivall, G.
Šafář, V.
Seredovich, V.A.
Pattabhi, Rama, Rao, E.
Ban, Y.
Gartner, G.
Dowman, I.
Streilein, A.
Olesovska, H.
Vondráková, A.
Holland, D.
Doytsher, Y.
Schreier, G.
Dvořáček, P.
Stylianidis, S.
Global status of mapping
Topographic mapping
Mapping
Military mapping
Navigation systems
Remote sensing
Data coverage
Global data
Map data
MicroSoft
Private industries
Questionnaire surveys
Topographic mapping
Working groups
Surveys
In December 2011, UNGGIM initiated a cooperative project with ISPRS to resume the former UN Secretariat studies on the status of topographic mapping in the world, conducted between 1968 and 1986. After the design of a questionnaire with 27 questions, the UNGGIM Secretariat sent the questionnaires to the UN member states. 115 replies were received from the 193 member states and regions thereof. Regarding the global data coverage and age, the UN questionnaire survey was supplemented by data from the Eastview database. For each of the 27 questions, an interactive viewer was programmed permitting the analysis of the results. The authoritative data coverage at the various scale ranges has greatly increased between 1986 and 2012. Now, a 30% 1:25 000 map data coverage and a 75% 1:50 000 map data coverage has been completed. Nevertheless, there is still an updating problem, as data for some countries is 10 to 30 years old. Private Industry, with Google, Microsoft and Navigation system providers, have undertaken huge efforts to supplement authoritative mapping. For critical areas on the globe, MGCP committed to military mapping at 1:50 000. ISPRS has decided to make such surveys a sustainable issue by establishing a working group.
2016-11-21T07:54:39Z
2016-11-21T07:54:39Z
2016
Article
Text
Konecny, G.; Breitkopf, U.; Radtke, A.: The status of topographic mapping in the world a UNGGIM - ISPRS project 2012-2015. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 737-741. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B4-737-2016
http://www.repo.uni-hannover.de/handle/123456789/717
http://dx.doi.org/10.15488/693
eng
XXIII ISPRS Congress, Commission IV
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B4
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B4-737-2016
https://doi.org/10.5194/isprsarchives-xli-b4-737-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7182023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:39Z
urn:hdl:123456789/718
Contextual land use classification: How detailed can the class structure be?
Albert, Lena
Rottensteiner, Franz
Heipke, Christian
Halounova, L.
Yang, C.P.
Remondino, F.
Zlatanova, S.
Muller, J.P.
Veenendaal, B.
Mu, L.
Oberst, J.
Ernst, J.
Jiang, J.
Voženílek, V.
Percivall, G.
Šafář, V.
Seredovich, V.A.
Pattabhi, Rama, Rao, E.
Ban, Y.
Gartner, G.
Dowman, I.
Streilein, A.
Olesovska, H.
Vondráková, A.
Holland, D.
Doytsher, Y.
Schreier, G.
Dvořáček, P.
Stylianidis, S.
Aerial imagery
Contextual classification
Geospatial land use database
Land use classification
Semantic resolution
Aerial photography
Classification (of information)
Database systems
Remote sensing
Semantics
Aerial imagery
Contextual classification
Contextual knowledge
Geo-spatial database
Hierarchical structures
High-resolution aerial images
The goal of this paper is to investigate the maximum level of semantic resolution that can be achieved in an automated land use change detection process based on mono-temporal, multi-spectral, high-resolution aerial image data. For this purpose, we perform a step-wise refinement of the land use classes that follows the hierarchical structure of most object catalogues for land use databases. The investigation is based on our previous work for the simultaneous contextual classification of aerial imagery to determine land cover and land use. Land cover is determined at the level of small image segments. Land use classification is applied to objects from the geospatial database. Experiments are carried out on two test areas with different characteristics and are intended to evaluate the step-wise refinement of the land use classes empirically. The experiments show that a semantic resolution of ten classes still delivers acceptable results, where the accuracy of the results depends on the characteristics of the test areas used. Furthermore, we confirm that the incorporation of contextual knowledge, especially in the form of contextual features, is beneficial for land use classification.
2016-11-21T07:54:39Z
2016-11-21T07:54:39Z
2016
Article
Text
Albert, L.; Rottensteiner, F.; Heipke, C.: Contextual land use classification: How detailed can the class structure be? In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 11-18. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B4-11-2016
http://www.repo.uni-hannover.de/handle/123456789/718
http://dx.doi.org/10.15488/694
eng
XXIII ISPRS Congress, Commission IV
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B4
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B4-11-2016
https://doi.org/10.5194/isprsarchives-xli-b4-11-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7192023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:39Z
urn:hdl:123456789/719
Accuracy assessment of mobile mapping point clouds using the existing environment as terrestrial reference
Hofmann, Sabine
Brenner, Claus
Halounova, L.
Šafář, V.
Toth, C.K.
Karas, J.
Huadong, G.
Haala, N.
Habib, A.
Reinartz, P.
Tang, X.
Li, J.
Armenakis, C.
Grenzdörffer, G.
le Roux, P.
Stylianidis, S.
Blasi, R.
Menard, M.
Dufourmount, H.
Li, Z.
3D test field
Accuracy assessment
Facades
Mobile mapping
Point cloud
Reference data
Street profile
Total station
Facades
Geodesy
Mapping
Remote sensing
Surveys
3d tests
Accuracy assessment
Mobile mapping
Point cloud
Reference data
Total station
Traffic signs
Mobile mapping data is widely used in various applications, what makes it especially important for data users to get a statistically verified quality statement on the geometric accuracy of the acquired point clouds or its processed products. The accuracy of point clouds can be divided into an absolute and a relative quality, where the absolute quality describes the position of the point cloud in a world coordinate system such as WGS84 or UTM, whereas the relative accuracy describes the accuracy within the point cloud itself. Furthermore, the quality of processed products such as segmented features depends on the global accuracy of the point cloud but mainly on the quality of the processing steps. Several data sources with different characteristics and quality can be thought of as potential reference data, such as cadastral maps, orthophoto, artificial control objects or terrestrial surveys using a total station. In this work a test field in a selected residential area was acquired as reference data in a terrestrial survey using a total station. In order to reach high accuracy the stationing of the total station was based on a newly made geodetic network with a local accuracy of less than 3 mm. The global position of the network was determined using a long time GNSS survey reaching an accuracy of 8 mm. Based on this geodetic network a 3D test field with facades and street profiles was measured with a total station, each point with a two-dimensional position and altitude. In addition, the surface of poles of street lights, traffic signs and trees was acquired using the scanning mode of the total station. Comparing this reference data to the acquired mobile mapping point clouds of several measurement campaigns a detailed quality statement on the accuracy of the point cloud data is made. Additionally, the advantages and disadvantages of the described reference data source concerning availability, cost, accuracy and applicability are discussed.
2016-11-21T07:54:39Z
2016-11-21T07:54:39Z
2016
Article
Text
Hofmann, S.; Brenner, C.: Accuracy assessment of mobile mapping point clouds using the existing environment as terrestrial reference. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 601-608. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B1-601-2016
http://www.repo.uni-hannover.de/handle/123456789/719
http://dx.doi.org/10.15488/695
eng
XXIII ISPRS Congress, Commission I
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B1
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B1-601-2016
https://doi.org/10.5194/isprsarchives-xli-b1-601-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7202023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:40Z
urn:hdl:123456789/720
Intersection detection based on qualitative spatial reasoning on stopping point clusters
Zourlidou, S.
Sester, Monika
Halounova, L.
Li, S.
Šafář, V.
Tomková, M.
Rapant, P.
Brázdil, K.
Shi, W. (John)
Anton, F.
Liu, Y.
Stein, A.
Cheng, T.
Pettit, C.
Li, Q.-Q.
Sester, M.
Mostafavi, M.A.
Madden, M.
Tong, X.
Brovelli, M.A.
HaeKyong, K.
Kawashima, H.
Coltekin, A.
Clustering
Geospatial analysis
Intersection detection
Point data analysis
Qualitative cluster reasoning
Relational reasoning
Rule-sensing
Semantic trajectories
Spatial reasoning
Stops and moves
Location
Remote sensing
Roads and streets
Semantics
Vehicles
Clustering
Geo-spatial analysis
Qualitative cluster reasoning
Relational reasoning
Rule-sensing
Semantic trajectories
Spatial reasoning
Trajectories
The purpose of this research is to propose and test a method for detecting intersections by analysing collectively acquired trajectories of moving vehicles. Instead of solely relying on the geometric features of the trajectories, such as heading changes, which may indicate turning points and consequently intersections, we extract semantic features of the trajectories in form of sequences of stops and moves. Under this spatiotemporal prism, the extracted semantic information which indicates where vehicles stop can reveal important locations, such as junctions. The advantage of the proposed approach in comparison with existing turning-points oriented approaches is that it can detect intersections even when not all the crossing road segments are sampled and therefore no turning points are observed in the trajectories. The challenge with this approach is that first of all, not all vehicles stop at the same location – thus, the stop-location is blurred along the direction of the road; this, secondly, leads to the effect that nearby junctions can induce similar stop-locations. As a first step, a density-based clustering is applied on the layer of stop observations and clusters of stop events are found. Representative points of the clusters are determined (one per cluster) and in a last step the existence of an intersection is clarified based on spatial relational cluster reasoning, with which less informative geospatial clusters, in terms of whether a junction exists and where its centre lies, are transformed in more informative ones. Relational reasoning criteria, based on the relative orientation of the clusters with their adjacent ones are discussed for making sense of the relation that connects them, and finally for forming groups of stop events that belong to the same junction.
2016-11-21T07:54:40Z
2016-11-21T07:54:40Z
2016
Article
Text
Zourlidou, S.; Sester, M.: Intersection detection based on qualitative spatial reasoning on stopping point clusters. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 269-276. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B2-269-2016
http://www.repo.uni-hannover.de/handle/123456789/720
http://dx.doi.org/10.15488/696
eng
XXIII ISPRS Congress, Commission II
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B2
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B2-269-2016
https://doi.org/10.5194/isprsarchives-xli-b2-269-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7212023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:40Z
urn:hdl:123456789/721
Analysis of spatio-temporal traffic patterns based on pedestrian trajectories
Busch, S.
Schindler, T.
Klinger, Tobias
Brenner, Claus
Halounova, L.
Li, S.
Šafář, V.
Tomková, M.
Rapant, P.
Brázdil, K.
Shi, W. (John)
Anton, F.
Liu, Y.
Stein, A.
Cheng, T.
Pettit, C.
Li, Q.-Q.
Sester, M.
Mostafavi, M.A.
Madden, M.
Tong, X.
Brovelli, M.A.
HaeKyong, K.
Kawashima, H.
Coltekin, A.
Dynamic prior map
Pedestrian behaviour prediction
Periodic event analysis
Traffic pattern
Walking path network
Automobile drivers
Complex networks
Remote sensing
Video recording
Dynamic priors
Event analysis
Pedestrian movement
Pedestrian trajectories
Public transportation
Traffic pattern
Trajectory segments
Walking paths
Trajectories
For driver assistance and autonomous driving systems, it is essential to predict the behaviour of other traffic participants. Usually, standard filter approaches are used to this end, however, in many cases, these are not sufficient. For example, pedestrians are able to change their speed or direction instantly. Also, there may be not enough observation data to determine the state of an object reliably, e.g. in case of occlusions. In those cases, it is very useful if a prior model exists, which suggests certain outcomes. For example, it is useful to know that pedestrians are usually crossing the road at a certain location and at certain times. This information can then be stored in a map which then can be used as a prior in scene analysis, or in practical terms to reduce the speed of a vehicle in advance in order to minimize critical situations. In this paper, we present an approach to derive such a spatio-temporal map automatically from the observed behaviour of traffic participants in everyday traffic situations. In our experiments, we use one stationary camera to observe a complex junction, where cars, public transportation and pedestrians interact. We concentrate on the pedestrians trajectories to map traffic patterns. In the first step, we extract trajectory segments from the video data. These segments are then clustered in order to derive a spatial model of the scene, in terms of a spatially embedded graph. In the second step, we analyse the temporal patterns of pedestrian movement on this graph. We are able to derive traffic light sequences as well as the timetables of nearby public transportation. To evaluate our approach, we used a 4 hour video sequence. We show that we are able to derive traffic light sequences as well as time tables of nearby public transportation.
2016-11-21T07:54:40Z
2016-11-21T07:54:40Z
2016
Article
Text
Busch, S.; Schindler, T.; Klinger, T.; Brenner, C.: Analysis of spatio-temporal traffic patterns based on pedestrian trajectories. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 497-503. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B2-497-2016
http://www.repo.uni-hannover.de/handle/123456789/721
http://dx.doi.org/10.15488/697
eng
XXIII ISPRS Congress, Commission II
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B2
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B2-497-2016
https://doi.org/10.5194/isprsarchives-xli-b2-497-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7222023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:40Z
urn:hdl:123456789/722
Network detection in raster data using marked point processes
Schmidt, Alena
Kruse, Christian
Rottensteiner, Franz
Sörgel, Uwe
Heipke, Christian
L. Halounova, L.
Schindler, K.
Limpouch, A.
Pajdla, T.
Šafář, V.
Mayer, H.
Oude Elberink, S.
Mallet, C.
Rottensteiner, F.
Brédif, M.
Skaloud, J.
Stilla, U.
Digital terrain models
Graph
Marked point processes
Networks
RJMCMC
Landforms
Markov processes
Networks (circuits)
Remote sensing
Stochastic models
Stochastic systems
Digital terrain model
Graph
Marked point process
Most probable configurations
Probabilistic framework
Reversible jump Markov chain Monte Carlo
We propose a new approach for the automatic detection of network structures in raster data. The model for the network structure is represented by a graph whose nodes and edges correspond to junction-points and to connecting line segments, respectively; nodes and edges are further described by certain parameters. We embed this model in the probabilistic framework of marked point processes and determine the most probable configuration of objects by stochastic sampling. That is, different graph configurations are constructed randomly by modifying the graph entity parameters, by adding and removing nodes and edges to/ from the current graph configuration. Each configuration is then evaluated based on the probabilities of the changes and an energy function describing the conformity with a predefined model. By using the Reversible Jump Markov Chain Monte Carlo sampler, a global optimum of the energy function is determined. We apply our method to the detection of river and tidal channel networks in digital terrain models. In comparison to our previous work, we introduce constraints concerning the flow direction of water into the energy function. Our goal is to analyse the influence of different parameter settings on the results of network detection in both, synthetic and real data. Our results show the general potential of our method for the detection of river networks in different types of terrain.
2016-11-21T07:54:40Z
2016-11-21T07:54:40Z
2016
Article
Text
Schmidt, A.; Kruse, C.; Rottensteiner, F.; Soergel, U.; Heipke, C.: Network detection in raster data using marked point processes. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 701-708. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B3-701-2016
http://www.repo.uni-hannover.de/handle/123456789/722
http://dx.doi.org/10.15488/698
eng
XXIII ISPRS Congress, Commission III
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B3
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B3-701-2016
https://doi.org/10.5194/isprsarchives-xli-b3-701-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7232023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T07:54:41Z
urn:hdl:123456789/723
Hierarchical higher order crf for the classification of airborne lidar point clouds in urban areas
Niemeyer, Joachim
Rottensteiner, Franz
Sörgel, Uwe
Heipke, Christian
L. Halounova, L.
Schindler, K.
Limpouch, A.
Pajdla, T.
Šafář, V.
Mayer, H.
Oude Elberink, S.
Mallet, C.
Rottensteiner, F.
Brédif, M.
Skaloud, J.
Stilla, U.
Classification
Contextual
Higher Order Random Fields
Lidar
Point Cloud
Urban
Optical radar
Random processes
Remote sensing
Semantics
Classification results
Conditional random field
Contextual
Contextual feature
Hierarchical approach
Point cloud
Random fields
Urban
Classification (of information)
We propose a novel hierarchical approach for the classification of airborne 3D lidar points. Spatial and semantic context is incorporated via a two-layer Conditional Random Field (CRF). The first layer operates on a point level and utilises higher order cliques. Segments are generated from the labelling obtained in this way. They are the entities of the second layer, which incorporates larger scale context. The classification result of the segments is introduced as an energy term for the next iteration of the point-based layer. This framework iterates and mutually propagates context to improve the classification results. Potentially wrong decisions can be revised at later stages. The output is a labelled point cloud as well as segments roughly corresponding to object instances. Moreover, we present two new contextual features for the segment classification: the distance and the orientation of a segment with respect to the closest road. It is shown that the classification benefits from these features. In our experiments the hierarchical framework improve the overall accuracies by 2.3% on a point-based level and by 3.0% on a segment-based level, respectively, compared to a purely point-based classification.
2016-11-21T07:54:41Z
2016-11-21T07:54:41Z
2016
Article
Text
Niemeyer, J.; Rottensteiner, F.; Soergel, U.; Heipke, C.: Hierarchical higher order crf for the classification of airborne lidar point clouds in urban areas. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 655-662. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B3-655-2016
http://www.repo.uni-hannover.de/handle/123456789/723
http://dx.doi.org/10.15488/699
eng
XXIII ISPRS Congress, Commission III
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B3
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B3-655-2016
https://doi.org/10.5194/isprsarchives-xli-b3-655-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7242023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T08:37:57Z
urn:hdl:123456789/724
Detecting linear features by spatial point processes
Chai, Dengfeng
Schmidt, Alena
Heipke, Christian
L. Halounova, L.
Schindler, K.
Limpouch, A.
Pajdla, T.
Šafář, V.
Mayer, H.
Oude Elberink, S.
Mallet, C.
Rottensteiner, F.
Brédif, M.
Skaloud, J.
Stilla, U.
Feature Detection
Global Optimization
Linear Feature
Markov Chain Monte Carlo
Simulated Annealing
Spatial Point Processes
Global optimization
Markov processes
Remote sensing
Simulated annealing
Data terms
Feature detection
Linear configuration
Linear feature
Markov Chain Monte-Carlo
Spatial point process
Feature extraction
This paper proposes a novel approach for linear feature detection. The contribution is twofold: a novel model for spatial point processes and a new method for linear feature detection. It describes a linear feature as a string of points, represents all features in an image as a configuration of a spatial point process, and formulates feature detection as finding the optimal configuration of a spatial point process. Further, a prior term is proposed to favor straight linear configurations, and a data term is constructed to superpose the points on linear features. The proposed approach extracts straight linear features in a global framework. The paper reports ongoing work. As demonstrated in preliminary experiments, globally optimal linear features can be detected.
2016-11-21T08:37:57Z
2016-11-21T08:37:57Z
2016
Article
Text
Chai, D.; Schmidt, A.; Heipke, C.: Detecting linear features by spatial point processes. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 41 (2016), S. 841-848. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B3-841-2016
http://www.repo.uni-hannover.de/handle/123456789/724
http://dx.doi.org/10.15488/700
eng
XXIII ISPRS Congress, Commission III
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLI-B3
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B3-841-2016
https://doi.org/10.5194/isprsarchives-xli-b3-841-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7252022-12-02T16:17:36Zcom_123456789_1col_123456789_3doc-type:BookPartdoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T08:37:58Z
urn:hdl:123456789/725
Pléiades project: Assessment of georeferencing accuracy, image quality, pansharpening performence and DSM/DTM quality
Topan, H.
Cam, A.
Özendi, M.
Oruç, M.
Jacobsen, Karsten
Taşkanat, T.
Halounova, L.
Šafář, V.
Toth, C.K.
Karas, J.
Huadong, G.
Haala, N.
Habib, A.
Reinartz, P.
Tang, X.
Li, J.
Armenakis, C.
Grenzdörffer, G.
le Roux, P.
Stylianidis, S.
Blasi, R.
Menard, M.
Dufourmount, H.
Li, Z.
DSM/DTM
Georeferencing Accuracy
Image Quality
Pansharpening
Pléiades
Application programs
Remote sensing
Rock mechanics
Signal to noise ratio
Statistics
Digital surface models
DSM/DTM
Georeferencing
Ground control points
Ground sampling distances
Pan-sharpening
Rational polynomial coefficients
Pléiades 1A and 1B are twin optical satellites of Optical and Radar Federated Earth Observation (ORFEO) program jointly running by France and Italy. They are the first satellites of Europe with sub-meter resolution. Airbus DS (formerly Astrium Geo) runs a MyGIC (formerly Pléiades Users Group) program to validate Pléiades images worldwide for various application purposes. The authors conduct three projects, one is within this program, the second is supported by BEU Scientific Research Project Program, and the third is supported by TÜBİTAK. Assessment of georeferencing accuracy, image quality, pansharpening performance and Digital Surface Model/Digital Terrain Model (DSM/DTM) quality subjects are investigated in these projects. For these purposes, triplet panchromatic (50 cm Ground Sampling Distance (GSD)) and VNIR (2 m GSD) Pléiades 1A images were investigated over Zonguldak test site (Turkey) which is urbanised, mountainous and covered by dense forest. The georeferencing accuracy was estimated with a standard deviation in X and Y (SX, SY) in the range of 0.45m by bias corrected Rational Polynomial Coefficient (RPC) orientation, using ~170 Ground Control Points (GCPs). 3D standard deviation of ±0.44m in X, ±0.51m in Y, and ±1.82m in Z directions have been reached in spite of the very narrow angle of convergence by bias corrected RPC orientation. The image quality was also investigated with respect to effective resolution, Signal to Noise Ratio (SNR) and blur coefficient. The effective resolution was estimated with factor slightly below 1.0, meaning that the image quality corresponds to the nominal resolution of 50cm. The blur coefficients were achieved between 0.39-0.46 for triplet panchromatic images, indicating a satisfying image quality. SNR is in the range of other comparable space borne images which may be caused by de-noising of Pléiades images. The pansharpened images were generated by various methods, and are validated by most common statistical metrics and also visual interpretation. The generated DSM and DTM were achieved with ±1.6m standard deviation in Z (SZ) in relation to a reference DTM.
2016-11-21T08:37:58Z
2016-11-21T08:37:58Z
2016
BookPart
Text
Topan, H.; Cam, A.; Özendi, M.; Oruç, M.; Jacobsen, K.; Taşkanat, T.: Pléiades project: Assessment of georeferencing accuracy, image quality, pansharpening performence and DSM/DTM quality. In: Halounova, L.; Šafář, V.; Toth, C.K. et al. (Eds.): XXIII ISPRS Congress, Commission I. Göttingen : Copernicus, 2016 (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 41-B1), S. 503-510. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B1-503-2016
http://www.repo.uni-hannover.de/handle/123456789/725
http://dx.doi.org/10.15488/701
eng
XXIII ISPRS Congress, Commission I
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 41-B1
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B1-503-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/7262022-12-02T16:17:36Zcom_123456789_1col_123456789_3doc-type:BookPartdoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-21T08:37:58Z
urn:hdl:123456789/726
Orientation of oblique airborne image sets - Experiences from the ISPRS/Eurosdr benchmark on multi-platform photogrammetry
Gerke, M.
Nex, F.
Remondino, F.
Jacobsen, Karsten
Kremer, J.
Karel, W.
Huf, H.
Ostrowski, W.
Halounova, L.
Šafář, V.
Toth, C.K.
Karas, J.
Huadong, G.
Haala, N.
Habib, A.
Reinartz, P.
Tang, X.
Li, J.
Armenakis, C.
Grenzdörffer, G.
le Roux, P.
Stylianidis, S.
Blasi, R.
Menard, M.
Dufourmount, H.
Li, Z.
Bundle adjustment
Oblique
Orientation
Tie point matching
Crystal orientation
Image processing
Photogrammetry
Random errors
Remote sensing
Bundle adjustments
Bundle block adjustments
Commercial packages
Current limitation
Multicamera systems
Oblique
Overlapping images
Tie points
Image matching
During the last decade the use of airborne multi camera systems increased significantly. The development in digital camera technology allows mounting several mid- or small-format cameras efficiently onto one platform and thus enables image capture under different angles. Those oblique images turn out to be interesting for a number of applications since lateral parts of elevated objects, like buildings or trees, are visible. However, occlusion or illumination differences might challenge image processing. From an image orientation point of view those multi-camera systems bring the advantage of a better ray intersection geometry compared to nadir-only image blocks. On the other hand, varying scale, occlusion and atmospheric influences which are difficult to model impose problems to the image matching and bundle adjustment tasks. In order to understand current limitations of image orientation approaches and the influence of different parameters such as image overlap or GCP distribution, a commonly available dataset was released. The originally captured data comprises of a state-of-the-art image block with very high overlap, but in the first stage of the so-called ISPRS/EUROSDR benchmark on multi-platform photogrammetry only a reduced set of images was released. In this paper some first results obtained with this dataset are presented. They refer to different aspects like tie point matching across the viewing directions, influence of the oblique images onto the bundle adjustment, the role of image overlap and GCP distribution. As far as the tie point matching is concerned we observed that matching of overlapping images pointing to the same cardinal direction, or between nadir and oblique views in general is quite successful. Due to the quite different perspective between images of different viewing directions the standard tie point matching, for instance based on interest points does not work well. How to address occlusion and ambiguities due to different views onto objects is clearly a non-solved research problem so far. In our experiments we also confirm that the obtainable height accuracy is better when all images are used in bundle block adjustment. This was also shown in other research before and is confirmed here. Not surprisingly, the large overlap of 80/80% provides much better object space accuracy – random errors seem to be about 2-3fold smaller compared to the 60/60% overlap. A comparison of different software approaches shows that newly emerged commercial packages, initially intended to work with small frame image blocks, do perform very well.
2016-11-21T08:37:58Z
2016-11-21T08:37:58Z
2016
BookPart
Text
Gerke, M.; Nex, F.; Remondino, F.; Jacobsen, K.; Kremer, J. et al.: Orientation of oblique airborne image sets - Experiences from the ISPRS/Eurosdr benchmark on multi-platform photogrammetry. In: In: Halounova, L.; Šafář, V.; Toth, C.K. et al. (Eds.): XXIII ISPRS Congress, Commission I. Göttingen : Copernicus, 2016 (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 41-B1), S. 185-191. DOI: http://dx.doi.org/10.5194/isprsarchives-XLI-B1-185-2016
http://www.repo.uni-hannover.de/handle/123456789/726
http://dx.doi.org/10.15488/702
eng
XXIII ISPRS Congress, Commission I
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences 41-B1
2194-9034
1682-1750
http://dx.doi.org/10.5194/isprsarchives-XLI-B1-185-2016
http://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/8142022-12-02T15:03:40Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:500
2016-11-30T11:45:35Z
urn:hdl:123456789/814
Recognition of Repetitive Movement Patterns – The Case of Football Analysis
Feuerhake, Udo
football analysis
pattern recognition
spatio-temporal analysis
trajectory
Analyzing sports like football is interesting not only for the sports team itself, but also for the public and the media. Both have recognized that using more detailed analyses of the teams’ behavior increases their attractiveness and also their performance. For this reason, the games and the individual players are recorded using specially developed tracking systems. The tracking solution usually comes with elementary analysis software allowing for basic statistical information extraction. Going beyond these simple statistics is a challenging task. However, it is worthwhile when it provides a better view into the tactics of team or the typical movements of an individual player. In this paper an approach for the recognition of movement patterns as an advanced analysis method is presented, which uses the players’ trajectories as input data. Besides individual movement patterns it is also able to detect patterns in relation to group movements. A detailed description is followed by a discussion of the approach, where different experiments on real trajectory datasets, even from other contexts than football, show the method’s benefits and features.
2016-11-30T11:45:35Z
2016-11-30T11:45:35Z
2016
Article
Text
Feuerhake, Udo: Recognition of Repetitive Movement Patterns – The Case of Football Analysis. In: ISPRS International Journal of Geo-Information 5 (2016), Nr. 11, 208. DOI: http://dx.doi.org/10.3390/ijgi5110208
http://www.repo.uni-hannover.de/handle/123456789/814
http://dx.doi.org/10.15488/790
eng
ISPRS International Journal of Geo-Information 5 (20169, Nr. 11
2220-9964
http://dx.doi.org/10.3390/ijgi5110208
https://creativecommons.org/licenses/by-nc-sa/4.0/
CC BY-NC-SA 4.0 Unported
Basel : MDPI Publishing
oai:www.repo.uni-hannover.de:123456789/14362022-12-02T16:17:36Zcom_123456789_1col_123456789_3doc-type:BookPartdoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2017-04-28T08:05:10Z
urn:hdl:123456789/1436
A new straight line reconstruction methodology from multi-spectral stereo aerial images
Ok, A.O.
Wegner, J.D.
Heipke, Christian
Rottensteiner, Franz
Sörgel, Uwe
Toprak, V.
Paradotitis, N.
Pierrot-Deseilligny, M.
Mallet, C.
Tournaire, O.
Line reconstruction
Pair-wise line matching
Stereo aerial images
Straight line extraction
Computer vision
Edge detection
Image analysis
Image processing
Image reconstruction
Photogrammetry
Principal component analysis
Urban growth
Aerial images
Line correspondence
Line-matching
Multi-spectral
Pre-processing
Stereo matching
Straight line extractions
Straight-line segments
Stereo image processing
In this study, a new methodology for the reconstruction of line features from multispectral stereo aerial images is presented. We take full advantage of the existing multispectral information in aerial images all over the steps of pre-processing and edge detection. To accurately describe the straight line segments, a principal component analysis technique is adapted. The line to line correspondences between the stereo images are established using a new pair-wise stereo matching approach. The approach involves new constraints, and the redundancy inherent in pair relations gives us a possibility to reduce the number of false matches in a probabilistic manner. The methodology is tested over three different urban test sites and provided good results for line matching and reconstruction.
2017-04-28T08:05:10Z
2017-04-28T08:05:10Z
2010
BookPart
Text
Ok, A.O.; Wegner, J.D.; Heipke, C.; Rottensteiner, F.; Soergel, U. et al.: A new straight line reconstruction methodology from multi-spectral stereo aerial images. In: Paparoditis, N.; Pierrot-Deseilligny, M.; Mallet, C.; Tournaire, O. (Eds.): ISPRS Technical Commission III Symposium. PCV 2010 - Photogrammetric Computer Vision and Image Analysis. London : International Society for Photogrammetry and Remote Sensing, 2010 (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 38 Part 3A), S. 25-30. https://www.isprs.org/proceedings/XXXVIII/part3/a/pdf/25_XXXVIII-part3A.pdf
http://www.repo.uni-hannover.de/handle/123456789/1436
http://dx.doi.org/10.15488/1411
eng
ISPRS Technical Commission III Symposium.
PCV 2010 - Photogrammetric Computer Vision and Image Analysis
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 38 Part 3A
2194-9034
1682-1750
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
London : International Society for Photogrammetry and Remote Sensing
oai:www.repo.uni-hannover.de:123456789/14382023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2017-04-28T08:05:11Z
urn:hdl:123456789/1438
Automated extraction of the Antarctic coastline using snakes
Klinger, T.
Heipke, Christian
Ott, N.
Schenke, H.W.
Ziems, M.
Antarctica
Automation
Coastline
Landsat
Mapping
Modelling
Snakes
Updating
Automation
Curve fitting
Geometrical optics
Ice
Image segmentation
Mapping
Models
Sea ice
Antarctica
Coastline
LANDSAT
Snakes
Updating
Landforms
In this paper we present an automatic approach for coastline detection from images which is based on parametric active contours (snakes). Snakes require the definition of an energy functional that reflects the underlying coastline model. As for Antarctica, our application domain, the coastline appearance in the used optical images is heterogeneous. Therefore, a single model does not work equally well in all situations. On the basis of an up-to-date Landsat mosaic three different models are formulated that match a large part of the Antarctic coastline, i.e. the transition from ice shelf to water, from ice shelf to sea ice and from rocky terrain to water. For each of the three different cases the energy terms are optimized based on the radiometric properties of the adjacent regions as well as the curvature and the potential change-rate of the coastline itself. A supervised classification for the three classes ice, water and rocky terrain controls the whole process by choosing the most applicable model for a certain image region. With a view to the practical application the developed approach was integrated into a semiautomatic system, where the human operator supervises the optimization process of the contour and interactively corrects the results if the system fails.
2017-04-28T08:05:11Z
2017-04-28T08:05:11Z
2010
Article
Text
Klinger, T.; Heipke, C.; Ott, N.; Schenke, H.W.; Ziems, M.: Automated extraction of the Antarctic coastline using snakes. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 38 (2010).
http://www.repo.uni-hannover.de/handle/123456789/1438
http://dx.doi.org/10.15488/1413
eng
Geospatial Data and Geovisualization: Environment, Security, and Society : Special Joint Symposium of ISPRS Commission IV and AutoCarto 2010 in conjunction with ASPRS/CaGIS 2010 Special Conference
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XXXVIII Part 4
https://www.isprs.org/proceedings/XXXVIII/part4/files/Klinger.pdf
2194-9034
1682-1750
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/14502022-12-02T16:17:36Zcom_123456789_1col_123456789_3doc-type:BookPartdoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2017-04-28T08:38:51Z
urn:hdl:123456789/1450
Incremental data acquisition from gps-traces
Zhang, L.
Sester, Monika
GPS data
Incremental refinement
Integration
Road map
Data acquisition
Data integration
Integration
Maps
Roads and streets
Attribute information
Centerlines
GPS data
Incremental data
Incremental refinement
Normal condition
Road-maps
Temporal analysis
Transportation
GPS traces can track actual time and coordinates of regular vehicles going their own business, and it is easy to scale to the entire area with an accuracy of 6 to 10 meters in normal condition. As a result, extracting road map from GPS traces could be an alternative way to traditional way of road map generation. The basic idea of this paper is to describe a process which incrementally improves existing road data with incoming new information in terms of GPS traces. In this way we consider the GPS traces as measurements which represent a "digitization" of the true road. Although the accuracy of the traces is not too high, due to the high number of measurements an improvement of the quality of the road information can be achieved. Thus, this paper presents a method for integrating GPS traces and an existing road map towards a more accurate, up-to-data and detailed road map. First we profile the existing road by a sequence of perpendicular profiles and get the road's candidate sampling traces which intersect with the profile. Then we match the potential traces with the road and finally estimate the new road centerline from its corresponding traces. In addition to the geometry of roads we also mine attribute information from GPS traces, such as number of lanes. Furthermore, we explore the benefit of an incremental acquisition by a temporal analysis of the data.
2017-04-28T08:38:51Z
2017-04-28T08:38:51Z
2011
BookPart
Text
Zhang, L.; Sester, M.: Incremental data acquisition from gps-traces. In: ISPRS Archives – Volume XXXVIII Part 4. Göttingen : Copernicus GmbH, 2011 (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 38-4). URL: https://www.isprs.org/proceedings/XXXVIII/part4/files/Zhang%20L.pdf
http://www.repo.uni-hannover.de/handle/123456789/1450
http://dx.doi.org/10.15488/1425
eng
ISPRS Archives – Volume XXXVIII Part 4
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; 38-4
2194-9034
1682-1750
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus Publications
oai:www.repo.uni-hannover.de:123456789/14592023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2017-04-28T08:38:54Z
urn:hdl:123456789/1459
Multiple-model based verification of japanese road data
Ziems, M.
Fujimura, H.
Heipke, Christian
Rottensteiner, Franz
Peled, Ammatzia
Classification
Databases
Modelling
Orthoimage
Quality
Updating
Classification (of information)
Database systems
Image quality
Maintenance
Models
Transportation
Dempster-Shafer fusion
Incomplete knowledge
Multiple-modeling
Orthoimages
Semi-automatic systems
Statistical properties
Updating
Verification results
Roads and streets
This paper describes a semi-automatic system for road verification from high resolution orthophotos in an urban context. The system combines several road detection and road verification approaches from current literature to form a more general solution. Each road detection / verification approach is realized as an independent module representing a unique road model and thus a unique strategy. The object-wise verification result of each module is formulated as a binary decision between the classes "correct road" and "incorrect road". These individual decisions are combined by Dempster-Shafer fusion, which provides tools for dealing with uncertain and incomplete knowledge about the statistical properties of the data. For each road detection / verification module a function for confidence is introduced that reflects degree of correspondence of an actual test situation with an optimal situation according to the underlying road model of that module. Experimental results achieved with four different test sites in Japan demonstrate the potential and confirm the reliability of the new system.
2017-04-28T08:38:54Z
2017-04-28T08:38:54Z
2010
Article
Text
Ziems, M.; Fujimura, H.; Heipke, C.; Rottensteiner, F.: Multiple-model based verification of japanese road data. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 38 (2010), S. 13-19.
http://www.repo.uni-hannover.de/handle/123456789/1459
http://dx.doi.org/10.15488/1434
eng
Core Spatial Databases - Updating, Maintenance and Services – from Theory to Practice
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XXXVIII-4-8-2/W9
https://www.isprs.org/proceedings/XXXVIII/4_8_2-W9/papers/final_27_ziems_etal.pdf
2194-9034
1682-1750
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/14682023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2017-04-28T09:12:00Z
urn:hdl:123456789/1468
Semiautomatic quality control of topographic reference datasets
Becker, Christian
Breitkopf, Uwe
Büschenfeld, Torsten
Busch, A.
Grünreich, D.
Heipke, Christian
Helmholz, Petra
Müller, S.
Ostermann, Jörn
Pahl, M.
Vogt, Karsten
Ziems, M.
Automation
Classification
Extraction
GIS
Inspection
Object
Quality
Updating
Automation
Classification (of information)
Extraction
Geographic information systems
Image quality
Inspection
Satellite imagery
Automatic image analysis
Disaster monitoring constellations
Geo-spatial data
High resolution satellite imagery
ITS applications
Object
Spatial information systems
Updating
Quality control
The usefulness and acceptance of spatial information systems are mainly dependent on the quality of the underlying geodata. This paper describes a system for semiautomatic quality control of existing geospatial data via automatic image analysis using aerial images, high-resolution satellite imagery (IKONOS and RapidEye) and low-resolution satellite imagery (Disaster Monitoring Constellation, DMC) with mono- and multi-temporal approaches focusing on objects which cover most of the area of the topographic dataset. The goal of the developed system is to reduce the manual efforts to a minimum. We shortly review the system design and then we focus on the automatic components and their integration in a semiautomatic workflow for verification and update. A prototype of the system has been in use for several years. From the experience gained during this time we give a detailed report on the system performance in its application as well as an evaluation of the results.
2017-04-28T09:12:00Z
2017-04-28T09:12:00Z
2010
Article
Text
Becker, C.; Breitkopf, U.; Büschenfeld, T.; Busch, A.; Grünreich, D. et al.: Semiautomatic quality control of topographic reference datasets. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 38 (2010).
http://www.repo.uni-hannover.de/handle/123456789/1468
http://dx.doi.org/10.15488/1443
eng
Geospatial Data and Geovisualization: Environment, Security, and Society : Special Joint Symposium of ISPRS Commission IV and AutoCarto 2010 in conjunction with ASPRS/CaGIS 2010 Special Conference
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XXXVIII-Part 4
https://www.isprs.org/proceedings/XXXVIII/part4/files/Becker.pdf
2194-9034
1682-1750
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/14712023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2017-04-28T09:12:01Z
urn:hdl:123456789/1471
Topographic estimation by TERRASAR-X
Sefercik, Umut Gunes
Sörgel, Uwe
W. Wagner, B. Székely
Accuracy
Analysis
Comparison
DEM
Estimation
Generation
Sar
Visualization
Estimation
Flow visualization
Geodetic satellites
Interferometry
Optical resolving power
Radar
Radar measurement
Remote sensing
Satellites
Space optics
Surveying
Synthetic aperture radar
Tracking radar
Accuracy
Analysis
Comparison
DEM
Generation
Sar
Space-based radar
SAR Interferometry (InSAR) is a technique to derive Digital Elevation Model (DEM) from at least two complex SAR images. The data are either taken simultaneously (single-pass mode) or sequentially (repeat-pass mode) by airborne or space-born sensors (carriers: plane, satellite, shuttle etc.). To date, one of the most important single-pass interferometry measurement campaigns is the Shuttle Radar Topography Mission (SRTM) completing its mission successfully after 11 days of operation between 11th and 22nd of February 2000. On the other hand, repeat-pass InSAR has been used by several satellite systems: ENVISAT, ERS 1-2, RADARSAT 1-2, ALOS, JERS-1 etc. One of the most advanced systems is the German TerraSAR-X (TSX) satellite launched on June 15th , 2007. TSX offers high resolution (∼1m by Spotlight mode) imagery which could not been achieved from radar technologies up to this time similar to high resolution optical imagery. In contrast to optical sensors, TSX can be operated under all weather conditions without being influenced by clouds. The data sets provided by TSX newly obtained by scientific community and evaluations are currently being performed. As mentioned above, utilizing the advantages of SAR technology, indeed the planimetric locations of target ground objects, elevations of them can be determined using interferometry. Through the interferometric data, interferograms (fringe maps) can be generated and applying interferometric processing steps height models can be created for large coverage interest areas. The main targets of this investigation can be summarized as; generation of height models derived from TSX InSAR image-pairs and evaluation by comparison with more accurate reference height models as well as height models based on high resolution optical satellite images. Absolute and relative accuracy, stability, homogeneity and dependency upon various parameters are determined. The approach will be demonstrated using TSX data covering Istanbul area, Turkey.
2017-04-28T09:12:01Z
2017-04-28T09:12:01Z
2010
Article
Text
Sefercik, U.G.; Soergel, U.: Topographic estimation by TERRASAR-X. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 38 (2010), S. 504-510.
http://www.repo.uni-hannover.de/handle/123456789/1471
http://dx.doi.org/10.15488/1446
eng
ISPRS Technical Commission VII Symposium 100 Years ISPRS : Advancing Remote Sensing Science
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XXXVIII-Part 7B
https://www.isprs.org/proceedings/XXXVIII/part7/b/pdf/504_XXXVIII-part7B.pdf
2194-9034
1682-1750
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/16842022-12-02T15:02:18Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2017-06-21T13:23:20Z
urn:hdl:123456789/1684
Neural networks for the generation of sea bed models using airborne lidar bathymetry data
Kogut, Tomasz
Niemeyer, Joachim
Bujakiewicz, Aleksandra
Airborne lidar bathymetry
Delaunay triangulation
Interpolation
Inverse distance weighting
Neural networks
Various sectors of the economy such as transport and renewable energy have shown great interest in sea bed models. The required measurements are usually carried out by ship-based echo sounding, but this method is quite expensive. A relatively new alternative is data obtained by airborne lidar bathymetry. This study investigates the accuracy of these data, which was obtained in the context of the project ‘Investigation on the use of airborne laser bathymetry in hydrographic surveying’. A comparison to multi-beam echo sounding data shows only small differences in the depths values of the data sets. The IHO requirements of the total horizontal and vertical uncertainty for laser data are met. The second goal of this paper is to compare three spatial interpolation methods, namely Inverse Distance Weighting (IDW), Delaunay Triangulation (TIN), and supervised Artificial Neural Networks (ANN), for the generation of sea bed models. The focus of our investigation is on the amount of required sampling points. This is analyzed by manually reducing the data sets. We found that the three techniques have a similar performance almost independently of the amount of sampling data in our test area. However, ANN are more stable when using a very small subset of points.
2017-06-21T13:23:20Z
2017-06-21T13:23:20Z
2016
Article
Text
Kogut, T.; Niemeyer, J.; Bujakiewicz, A.: Neural networks for the generation of sea bed models using airborne lidar bathymetry data. In: Geodesy and Cartography 65 (2016), Nr. 1, S. 41-53. DOI: https://doi.org/10.1515/geocart-2016-0007
http://www.repo.uni-hannover.de/handle/123456789/1684
http://dx.doi.org/10.15488/1659
eng
Geodesy and Cartography 65 (2016), Nr. 1
2029-6991
https://doi.org/10.1515/geocart-2016-0007
https://creativecommons.org/licenses/by-nc-nd/3.0/
CC BY-NC-ND 3.0 Unported
Abingdon : Taylor and Francis Ltd.
oai:www.repo.uni-hannover.de:123456789/17592022-12-02T15:17:15Zcom_123456789_1col_123456789_7doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2017-07-17T11:09:07Z
urn:hdl:123456789/1759
Search for Gravitational Waves Associated with Gamma-Ray Bursts during the First Advanced LIGO Observing Run and Implications for the Origin of GRB 150906B
Abbott, B.P.
Allen, Bruce
Aufmuth, Peter
Danzmann, Karsten
Vahlbruch, H.
et al.
IPN Collaboration
binaries: close
gamma-ray burst: general
gravitational waves
Gravitationswelle
We present the results of the search for gravitational waves (GWs) associated with γ-ray bursts detected during the first observing run of the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO). We find no evidence of a GW signal for any of the 41 γ-ray bursts for which LIGO data are available with sufficient duration. For all γ-ray bursts, we place lower bounds on the distance to the source using the optimistic assumption that GWs with an energy of were emitted within the – Hz band, and we find a median 90% confidence limit of 71 Mpc at 150 Hz. For the subset of 19 short/hard γ-ray bursts, we place lower bounds on distance with a median 90% confidence limit of 90 Mpc for binary neutron star (BNS) coalescences, and 150 and 139 Mpc for neutron star–black hole coalescences with spins aligned to the orbital angular momentum and in a generic configuration, respectively. These are the highest distance limits ever achieved by GW searches. We also discuss in detail the results of the search for GWs associated with GRB 150906B, an event that was localized by the InterPlanetary Network near the local galaxy NGC 3313, which is at a luminosity distance of Mpc (z = 0.0124). Assuming the γ-ray emission is beamed with a jet half-opening angle , we exclude a BNS and a neutron star–black hole in NGC 3313 as the progenitor of this event with confidence >99%. Further, we exclude such progenitors up to a distance of 102 Mpc and 170 Mpc, respectively.
2017-07-17T11:09:07Z
2017-07-17T11:09:07Z
2017
Article
Text
Abbott, B.P.; Allen, B.; Aufmuth, P.; Danzmann, K.; Vahlbruch, H.; et al. (The IPN Collaboration): Search for Gravitational Waves Associated with Gamma-Ray Bursts during the First Advanced LIGO Observing Run and Implications for the Origin of GRB 150906B. In: Astrophysical Journal 841 (2017), Nr. 2, 89. DOI: https://doi.org/10.3847/1538-4357/aa6c47
http://www.repo.uni-hannover.de/handle/123456789/1759
http://dx.doi.org/10.15488/1734
eng
Astrophysical Journal 841 (2017), Nr. 2
1538-4357
https://doi.org/10.3847/1538-4357/aa6c47
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Bristol : IOP Publishing Ltd.
oai:www.repo.uni-hannover.de:123456789/20152022-12-02T15:02:17Zcom_123456789_1col_123456789_3ddc:550doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2017-10-10T07:24:40Z
urn:hdl:123456789/2015
Correspondência eficiente de descritores SIFT para construção de mapas densos de pontos homólogos em imagens de sensoriamento remoto [Efficient matching steps of the SIFT for constructing a dense map of conjugate points in remote sensing images]
Silveira, Marcelo Teixeira
Feitosa, Raul Queiroz
Silva Brito, Jorge Luis Nunes E.
Jacobsen, Karsten
photogrammetry
least square correlation
least square matching
region growth
sift
lsm
dem
dsm
stereo
features
localization
keypoints
Area-based automatic image matching combined with a region-growing technique are able to provide a dense and accurate set of corresponding points. However, the region-growing process may stop at image patches where the horizontal x-parallax has an abrupt change. In such cases new pairs of corresponding points (seeds) must be provided, usually by a human operator. The region growing procedure restarts then from the new seed points. Depending upon the type of image and the 3D-structure of the mapped area, the human intervention may be considerable. A fully automatic alternative for finding conjugate points in stereo pairs was proposed by the authors in a prior work. The method combines the scale invariant feature transform, the Least-Squares matching and the region-growing technique. This work presents an extension of that technique. Basically, improvements in the matching step of the SIFT algorithm are proposed, which explores properties of stereo images produced by aerial and orbital sensors. Experiments conducted on stereo pairs from both airborne and satellite imagery show that the benefit of the proposed changes is twofold. Firstly, the number of true substantially with no significant increase in the proportion Secondly, the computational load is dramatically reduced.
Métodos automáticos de localização de pontos homólogos em imagens digitais baseados em área, combinados com técnicas de crescimento de região, são capazes de produzir uma malha densa e exata de pontos homólogos. Entretanto, o processo de crescimento de região pode ser interrompido em regiões da imagem, cuja paralaxe no eixo horizontal apresenta variação abrupta. Essa situação geralmente é causada por uma descontinuidade na superfície ou espaço-objeto imageado, tal como um prédio numa cena urbana ou um paredão de exploração de uma mina a céu aberto. Nesses casos, novos pares de pontos homólogos (sementes) devem ser introduzidos, normalmente por um operador humano, a partir dos quais o processo é reiniciado. Dependendo do tipo da imagem utilizada e da estrutura 3D da região mapeada, a intervenção humana pode ser considerável. Uma alternativa totalmente automatizada em que se combinam as técnicas SIFT (Scale Invariant Feature Transform), pareamento por mínimos quadrados e crescimento de região foi proposta anteriormente pelos autores. O presente trabalho apresenta uma extensão a essa técnica. Basicamente, propõem-se alterações na etapa de correspondência do SIFT, que exploram características de estereogramas produzidos por sensores aéreos e orbitais. Avaliações experimentais demonstram que as modificações propostas trazem dois tipos de benefícios. Em primeiro lugar, obtém-se um aumento do número de pontos homólogos encontrados, sem aumento correspondente na proporção de falsas correspondências. Em segundo lugar, a carga computacional é reduzida substancialmente.
2017-10-10T07:24:40Z
2017-10-10T07:24:40Z
2011
Article
Text
Silveira, Marcelo Teixeira; Feitosa, Raul Queiroz; Silva Brito, Jorge Luis Nunes E.; Jacobsen, Karsten: Correspondência eficiente de descritores SIFT para construção de mapas densos de pontos homólogos em imagens de sensoriamento remoto [Efficient matching steps of the SIFT for constructing a dense map of conjugate points in remote sensing images]. In: Boletim De Ciencias Geodesicas 17 (2011), Nr. 1, S. 130-160. DOI: https://doi.org/10.1590/S1982-21702011000100008
http://www.repo.uni-hannover.de/handle/123456789/2015
http://dx.doi.org/10.15488/1990
por
Boletim De Ciencias Geodesicas 17 (2011), Nr. 1
1413-4853
https://doi.org/10.1590/S1982-21702011000100008
https://creativecommons.org/licenses/by/4.0/deed.en
CC BY 4.0 Unported
Curitiba Pr : Univ. Federal Parana, Centro Politecnico
oai:www.repo.uni-hannover.de:123456789/22972022-12-02T15:15:02Zcom_123456789_1col_123456789_7doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2017-11-13T08:18:11Z
urn:hdl:123456789/2297
Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
Abbott, B.P.
Abbott, R.
Abbott, T.D.
Acernese, F.
Ackley, K.
et al.
LIGO Scientific Collaboration
Virgo Collaboration
binaries: close
gamma-ray burst: general
gravitational waves
Gravitationswelle
On 2017 August 17, the gravitational-wave event GW170817 was observed by the Advanced LIGO and Virgo detectors, and the gamma-ray burst (GRB) GRB 170817A was observed independently by the Fermi Gamma-ray Burst Monitor, and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory. The probability of the near-simultaneous temporal and spatial observation of GRB 170817A and GW170817 occurring by chance is . We therefore confirm binary neutron star mergers as a progenitor of short GRBs. The association of GW170817 and GRB 170817A provides new insight into fundamental physics and the origin of short GRBs. We use the observed time delay of between GRB 170817A and GW170817 to: (i) constrain the difference between the speed of gravity and the speed of light to be between and times the speed of light, (ii) place new bounds on the violation of Lorentz invariance, (iii) present a new test of the equivalence principle by constraining the Shapiro delay between gravitational and electromagnetic radiation. We also use the time delay to constrain the size and bulk Lorentz factor of the region emitting the gamma-rays. GRB 170817A is the closest short GRB with a known distance, but is between 2 and 6 orders of magnitude less energetic than other bursts with measured redshift. A new generation of gamma-ray detectors, and subthreshold searches in existing detectors, will be essential to detect similar short bursts at greater distances. Finally, we predict a joint detection rate for the Fermi Gamma-ray Burst Monitor and the Advanced LIGO and Virgo detectors of 0.1–1.4 per year during the 2018–2019 observing run and 0.3–1.7 per year at design sensitivity.
2017-11-13T08:18:11Z
2017-11-13T08:18:11Z
2017
Article
Text
Abbott, B.P.; Abbott, R.; Abbott, T.D.; Acernese, F.; Ackley, K.et, al., (LIGO Scientific Collaboration and Virgo Collaboration, Fermi Gamma-ray Burst Monitor, and INTEGRAL): Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A. In: Astrophysical Journal Letters 848 (2017), Nr. 2, L13. DOI: https://doi.org/10.3847/2041-8213/aa920c
http://www.repo.uni-hannover.de/handle/123456789/2297
http://dx.doi.org/10.15488/2271
eng
Astrophysical Journal Letters 848 (2017), Nr. 2
2041-8213
2041-8205
https://doi.org/10.3847/2041-8213/aa920c
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Bristol : Institute of Physics Publishing
oai:www.repo.uni-hannover.de:123456789/26802022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2018-01-26T12:22:38Z
urn:hdl:123456789/2680
Pole coordinates from the analysis of LLR data
Biskupek, Liliane
Hofmann, Franz
Müller, Jürgen
Lunar Laser Ranging
Pole coordinates
Polkoordinaten
The observations from Lunar Laser Ranging (LLR) are analysed and various parameters of the Earth-Moon system are determined by least-squares adjustment (e.g., station and reflector coordinates, lunar orbit and rotation). It is also possible to investigate EOPs like xP, yP and UT0-UTC from LLR data. In our previous study, the EOPs were determined in a post processing step after the global least-squares adjustment. However, in this way the correlation between EOPs and other parameters of the Earth-Moon system could not be investigated. In our recent analysis, values for xP, yP and UT0-UTC are determined directly in the global adjustment. Correlations with other parameters of the Earth-Moon system are automatically obtained. The LLR results for the EOPs are also compared to results determined from VLBI and GPS.
2018-01-26T12:22:38Z
2018-01-26T12:22:38Z
2018-01-26
ConferenceObject
Text
Biskupek, L.; Hofmann, F.; Müller, J.: Pole coordinates from the analysis of LLR data. – Hannover : Institutionelles Repositorium der Leibniz Universität Hannover, 2009. DOI: https://doi.org/10.15488/2654
http://www.repo.uni-hannover.de/handle/123456789/2680
http://dx.doi.org/10.15488/2654
eng
info:eu-repo/grantAgreement/DFG/FOR/584/EU
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Hannover : Institutionelles Repositorium der Leibniz Universität Hannover
oai:www.repo.uni-hannover.de:123456789/31822022-12-13T15:12:26Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2018-04-19T07:53:03Z
urn:hdl:123456789/3182
Robust Spatial Approximation of Laser Scanner Point Clouds by Means of Free-form Curve Approaches in Deformation Analysis
Bureick, Johannes
Alkhatib, Hamza
Neumann, Ingo
B-Splines
Deformation
Free-form Curve
Knot Adjustment
Monte-Carlo Resampling Techniques
Robust Parameter Estimation
Deformation
Interpolation
Laser applications
Railroad tracks
Scanning
Ship propellers
Splines
Statistics
B splines
Free form curve
Knot adjustments
Resampling technique
Robust parameter estimation
Monte Carlo methods
In many geodetic engineering applications it is necessary to solve the problem of describing a measured data point cloud, measured, e. g. by laser scanner, by means of free-form curves or surfaces, e. g., with B-Splines as basis functions. The state of the art approaches to determine B-Splines yields results which are seriously manipulated by the occurrence of data gaps and outliers. Optimal and robust B-Spline fitting depend, however, on optimal selection of the knot vector. Hence we combine in our approach Monte-Carlo methods and the location and curvature of the measured data in order to determine the knot vector of the B-Spline in such a way that no oscillating effects at the edges of data gaps occur. We introduce an optimized approach based on computed weights by means of resampling techniques. In order to minimize the effect of outliers, we apply robust M-estimators for the estimation of control points. The above mentioned approach will be applied to a multi-sensor system based on kinematic terrestrial laserscanning in the field of rail track inspection. © 2016 Walter de Gruyter GmbH, Berlin/Munich/Boston.
2018-04-19T07:53:03Z
2018-04-19T07:53:03Z
2016
Article
Text
Bureick, J.; Alkhatib, H.; Neumann, I.: Robust Spatial Approximation of Laser Scanner Point Clouds by Means of Free-form Curve Approaches in Deformation Analysis. In: Journal of Applied Geodesy 10 (2016), Nr. 1, S. 27-35. DOI: https://doi.org/10.1515/jag-2015-0020
http://www.repo.uni-hannover.de/handle/123456789/3182
http://dx.doi.org/10.15488/3152
eng
Journal of Applied Geodesy 10 (2016), Nr. 1
1862-9016
https://doi.org/10.1515/jag-2015-0020
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
Berlin : De Gruyter
oai:www.repo.uni-hannover.de:123456789/31972022-12-13T15:12:26Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2018-04-19T08:18:45Z
urn:hdl:123456789/3197
Utility theory as a method to minimise the risk in deformation analysis decisions
Zhang, Yin
Neumann, Ingo
decision making
deformation monitoring
hypothesis testing
risk analysis
utility theory
Algorithms
Decision making
Decision theory
Deformation
Probability density function
Risk analysis
Statistical tests
Alternative hypothesis
Deformation analysis
Deformation monitoring
Hypothesis testing
Individual monitoring
Measurement process
Probability density functions (PDFs)
Utility theory
Risk assessment
collapse
decision making
deformation
hypothesis testing
monitoring
probability
Deformation monitoring usually focuses on the detection of whether the monitored objects satisfy the given properties (e.g. being stable or not), and makes further decisions to minimise the risks, for example, the consequences and costs in case of collapse of artificial objects and/or natural hazards. With this intention, a methodology relying on hypothesis testing and utility theory is reviewed in this paper. The main idea of utility theory is to judge each possible outcome with a utility value. The presented methodology makes it possible to minimise the risk of an individual monitoring project by considering the costs and consequences of overall possible situations within the decision process. It is not the danger that the monitored object may collapse that can be reduced. The risk (based on the utility values multiplied by the danger) can be described more appropriately and therefore more valuable decisions can be made. Especially, the opportunity for the measurement process to minimise the risk is an important key issue. In this paper, application of the methodology to two of the classical cases in hypothesis testing will be discussed in detail: 1) both probability density functions (pdfs) of tested objects under null and alternative hypotheses are known; 2) only the pdf under the null hypothesis is known and the alternative hypothesis is treated as the pure negation of the null hypothesis. Afterwards, a practical example in deformation monitoring is introduced and analysed. Additionally, the way in which the magnitudes of utility values (consequences of a decision) influence the decision will be considered and discussed at the end.
2018-04-19T08:18:45Z
2018-04-19T08:18:45Z
2014
Article
Text
Zhang, Y.; Neumann, I.: Utility theory as a method to minimise the risk in deformation analysis decisions. In: Journal of Applied Geodesy 8 (2014), Nr. 4, S. 283-293. DOI: https://doi.org/10.1515/jag-2014-0012
http://www.repo.uni-hannover.de/handle/123456789/3197
http://dx.doi.org/10.15488/3167
eng
Journal of Applied Geodesy 8 (2014), Nr. 4
1862-9016
https://doi.org/10.1515/jag-2014-0012
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
Berlin : De Gruyter
oai:www.repo.uni-hannover.de:123456789/32262023-04-13T13:16:59Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2018-04-27T12:18:19Z
urn:hdl:123456789/3226
Security event recognition for visual surveillance
Liao, Wentong
Yang, Chun
Ying Yang, Michael
Rosenhahn, Bodo
Heipke, C.
Jacobsen, K.
Stilla, U.
Rottensteiner, F.
Yilmaz, A.
Ying Yang, M.
Skaloud, J.
Colomina, I.
Computer Vision
Convolutional Neural Network
Event Recognition
Video Surveillance
With rapidly increasing deployment of surveillance cameras, the reliable methods for automatically analyzing the surveillance video and recognizing special events are demanded by different practical applications. This paper proposes a novel effective framework for security event analysis in surveillance videos. First, convolutional neural network (CNN) framework is used to detect objects of interest in the given videos. Second, the owners of the objects are recognized and monitored in real-time as well. If anyone moves any object, this person will be verified whether he/she is its owner. If not, this event will be further analyzed and distinguished between two different scenes: moving the object away or stealing it. To validate the proposed approach, a new video dataset consisting of various scenarios is constructed for more complex tasks. For comparison purpose, the experiments are also carried out on the benchmark databases related to the task on abandoned luggage detection. The experimental results show that the proposed approach outperforms the state-of-the-art methods and effective in recognizing complex security events. © 2017 Copernicus GmbH. All rights reserved.
2018-04-27T12:18:19Z
2018-04-27T12:18:19Z
2017
Article
Text
Liao, W.; Yang, C.; Ying, Yang, M.; Rosenhahn, B.: Security event recognition for visual surveillance. In: ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences 4 (2017), Nr. 1W1, S. 19-26. DOI: https://doi.org/10.5194/isprs-annals-IV-1-W1-19-2017
http://www.repo.uni-hannover.de/handle/123456789/3226
http://dx.doi.org/10.15488/3196
eng
ISPRS Hannover Workshop: HRIGI 17 - CMRT 17 - ISA 17 - EuroCOW 17 : 6-9 June 2017, Hannover, Germany
ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; IV-1/W1
2194-9050
2194-9042
https://doi.org/10.5194/isprs-annals-IV-1-W1-19-2017
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/33332023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2018-05-18T09:47:41Z
urn:hdl:123456789/3333
Accuracy analysis of digital orthophotos from very high resolution imagery
Passini, Ricardo
Jacobsen, Karsten
Altan, Orhan
DEM/DTM
High resolution
Matching
Orientation
Orthoimage
Satellite
Antennas
Crystal orientation
Image coding
Orbits
Rock mechanics
Satellites
DEM/DTM
Digital elevation model
High resolution
Independent check points
Matching
Orthoimages
Rational polynomial coefficients
Very high resolution
Surveying
The generation of digital Orthophotos now days can be done with aerial, but also very high resolution space imagery. For a real competition the geometric and radiometric quality has to be on the same level. Different QuickBird images have been used for the generation of orthophotos with 1m pixel size. The whole procedure from the orientation up to the final step has been analyzed in detail. Rational polynomial coefficients (RPC) and bundle orientation using orbit information was used for the handling of QuickBird Basic and Standard Imagery. The special problems of individual and combined scenes are analyzed. QuickBird Images covering quite different areas were used. The effect of varying control point distributions on the accuracy, determined with independent check points was studied. Different sources of ground control like digital orthophoto quads, existing information from airborne photo flights and GPS-control points have been used. The required height information came from different digital elevation models (DEM) and ground survey. Satisfying results have been achieved. © 2004 International Society for Photogrammetry and Remote Sensing. All rights reserved.
2018-05-18T09:47:41Z
2018-05-18T09:47:41Z
2004
Article
Text
Passini, Ricardo; Jacobsen, Karsten: Accuracy analysis of digital orthophotos from very high resolution imagery. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 35, Part B4 (2004), S. 695-700.
http://www.repo.uni-hannover.de/handle/123456789/3333
http://dx.doi.org/10.15488/3303
eng
XXth ISPRS Congress : Technical Commission IV
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XXXV-B4
https://www.isprs.org/proceedings/XXXV/congress/comm4/papers/437.pdf
2194-9034
1682-1750
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/33342023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2018-05-18T09:47:42Z
urn:hdl:123456789/3334
Analysis of height models based on Kompsat-3 images
Büyüksalih, G.
Bayburt, S.
Jacobsen, K.
Tanzi, T.
Sunar, F.
Altan, O.
Chandra, M.
Area based matching
Height model
Image geometry
Kompsat-3
SGM
Disaster prevention
Disasters
Rock mechanics
Roof coverings
Systematic errors
Tracking radar
Area-based matching
Disaster management
Ground control points
Ground sampling distances
Image geometries
Kompsat-3
Least-squares matching
Semi-global matching
Stereo image processing
Height models are basic information required for disaster Management. Not in any case satisfying and actual height models are available, but they can be generated by satellite stereo pairs being more precise as InSAR. The Korean Kompsat-3 has a ground sampling distance of 0.71m. A stereo combination covering the main part of Istanbul has been used for the generation of height models. Kompsat-3 images are available as L1R images, corresponding close to the original image geometry, and as L1G, being projected to the SRTM 3 arcsec height model. For use of Semi Global Matching quasi epipolar images are required. They can be produced by just rotating the L1G-images to the stereo base, while with L1R-images requires at first a projection to a constant height level. The projection of L1G to the SRTM height models leads to height differences against the SRTM heights. The orientation of the L1R images with 71 ground control points (GCP) was possible in X and Y with 0.6 GSD and in Z with 1.1 GSD, while with L1G images only 1.2 GSD respectively 2.9 GSD have been reached. A standard deviation of 0.6 GSD for X and Y and 1.1 GSD for Z is satisfying and a usual accuracy for satellite images. A comparison of the generated height model based on the L1G-images with airborne LiDAR data (ALS) showed clear local systematic height errors of the height model based on L1G-images which could not be seen with L1R-images. The area based least squares matching leads to good results in open areas while in build up areas no accurate building determination is possible. Here SGM has a clear advantage with accurate roof structures corresponding to the 0.71m GSD. For the relative accuracy, that means the building height and the roof structure, it does not matter if L1G or L1R images are used. © Authors 2018. CC BY 4.0 License.
2018-05-18T09:47:42Z
2018-05-18T09:47:42Z
2018
Article
Text
Büyüksalih, G.; Bayburt, S.; Jacobsen, K.: Analysis of height models based on Kompsat-3 images. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 42 (2018), Nr. 3W4, S. 115-119. DOI: https://doi.org/10.5194/isprs-archives-XLII-3-W4-115-2018
http://www.repo.uni-hannover.de/handle/123456789/3334
http://dx.doi.org/10.15488/3304
eng
GeoInformation for Disaster Management : 18-21 March 2018, Istanbul, Turkey
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XLII-3/W4
2194-9034
1682-1750
https://doi.org/10.5194/isprs-archives-XLII-3-W4-115-2018
https://doi.org/10.5194/isprs-archives-xlii-3-w4-115-2018
https://creativecommons.org/licenses/by/4.0/
CC BY 4.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/33392023-04-17T15:25:14Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2018-05-18T09:47:45Z
urn:hdl:123456789/3339
Buhom: A Program for enhancement of geometric topologic consistency of building objects
Bildirici, I.O.
Heidorn, D.
Altan, Orhan
Building generalization
Digitizing errors
Generalization
Vector data
Errors
Angle adjustments
Automatic vectorization
Generalization
Geometric quality
GIS application
Process building
Vector data
Buildings
Vector data is captured using various methods, e.g. manual digitizing, automatic vectorization etc. Errors or inconsistencies, e.g. self-cutting polygons, identical points etc, can not be avoided, even if digitizing is done very carefully. Vector data must be analyzed and corrected prior to any GIS application. This process is called "line-cleaning". In this paper we introduce a computer program that is capable of analyzing of building objects. It can correct digitizing errors and improve geometric quality of data, doing right angle adjustment, making buildings parallel to streets etc. The program was designed to process building objects before generalization with CHANGE generalization software package. However, it can also be used independently. © 2004 International Society for Photogrammetry and Remote Sensing. All rights reserved.
2018-05-18T09:47:45Z
2018-05-18T09:47:45Z
2004
Article
Text
Bildirici, I.O.; Heidorn, D.: Buhom: A Program for enhancement of geometric topologic consistency of building objects. In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives 35, Part B4 (2004), S. 234-237.
http://www.repo.uni-hannover.de/handle/123456789/3339
http://dx.doi.org/10.15488/3309
eng
XXth ISPRS Congress : Technical Commission IV
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; XXXV-B4
https://www.isprs.org/proceedings/XXXV/congress/comm4/papers/348.pdf
2194-9034
1682-1750
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/33422023-04-13T13:16:59Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2018-05-18T09:47:46Z
urn:hdl:123456789/3342
Classification under label noise based on outdated maps
Maas, A.
Rottensteiner, Franz
Heipke, Christian
Heipke, C.
Jacobsen, K.
Stilla, U.
Rottensteiner, F.
Yilmaz, A.
Ying Yang, M.
Skaloud, J.
Colomina, I.
Label Noise
Logistic Regression
Map Updating
Supervised Classification
Supervised classification of remotely sensed images is a classical method for change detection. The task requires training data in the form of image data with known class labels, whose manually generation is time-consuming. If the labels are acquired from the outdated map, the classifier must cope with errors in the training data. These errors, referred to as label noise, typically occur in clusters in object space, because they are caused by land cover changes over time. In this paper we adapt a label noise tolerant training technique for classification, so that the fact that changes affect larger clusters of pixels is considered. We also integrate the existing map into an iterative classification procedure to act as a prior in regions which are likely to contain changes. Our experiments are based on three test areas, using real images with simulated existing databases. Our results show that this method helps to distinguish between real changes over time and false detections caused by misclassification and thus improves the accuracy of the classification results. © 2017 Copernicus GmbH. All rights reserved.
2018-05-18T09:47:46Z
2018-05-18T09:47:46Z
2017
Article
Text
Maas, A.; Rottensteiner, F.; Heipke, C.: Classification under label noise based on outdated maps. In: ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences 4 (2017), Nr. 1W1, S. 215-222. DOI: https://doi.org/10.5194/isprs-annals-IV-1-W1-215-2017
http://www.repo.uni-hannover.de/handle/123456789/3342
http://dx.doi.org/10.15488/3312
eng
ISPRS Hannover Workshop: HRIGI 17 - CMRT 17 - ISA 17 - EuroCOW 17 : 6-9 June 2017, Hannover, Germany
ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; IV-1/W1
2194-9050
2194-9042
https://doi.org/10.5194/isprs-annals-IV-1-W1-215-2017
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/34262023-04-13T13:16:59Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2018-05-23T11:41:22Z
urn:hdl:123456789/3426
Timestamp offset determination between an actuated laser scanner and its corresponding motor
Voges, Raphael
Wieghardt, Christian S.
Wagner, Bernardo
Heipke, C.
Jacobsen, K.
Stilla, U.
Rottensteiner, F.
Yilmaz, A.
Ying Yang, M.
Skaloud, J.
Colomina, I.
3D Perception
Actuated lidar
Laser Range Finder
Rotating laser
Sensor Synchronization
SLAM
Timestamp Offsets
Motor actuated 2D laser scanners are key sensors for many robotics applications that need wide ranging but low cost 3D data. There exist many approaches on how to build a 3D laser scanner using this technique, but they often lack proper synchronization for the timestamps of the actuator and the laser scanner. However, to transform the measurement points into three-dimensional space an appropriate synchronization is mandatory. Thus, we propose two different approaches to accomplish the goal of calculating timestamp offsets between laser scanner and motor prior to and after data acquisition. Both approaches use parts of a SLAM algorithm but apply different criteria to find an appropriate solution. While the approach for offset calculation prior to data acquisition exploits the fact that the SLAM algorithm should not register motion for a stationary system, the approach for offset calculation after data acquisition evaluates the perceived clarity of a point cloud created by the SLAM algorithm. Our experiments show that both approaches yield the same results although operating independently on different data, which demonstrates that the results reflect reality with a high probability. Furthermore, our experiments exhibit the significance of a proper synchronization between laser scanner and actuator.
2018-05-23T11:41:22Z
2018-05-23T11:41:22Z
2017
Article
Text
Voges, R.; Wieghardt, C.S.; Wagner, B.: Timestamp offset determination between an actuated laser scanner and its corresponding motor. In: ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences 4 (2017), Nr. 1W1, S. 99-106. DOI: https://doi.org/10.5194/isprs-annals-IV-1-W1-99-2017
http://www.repo.uni-hannover.de/handle/123456789/3426
http://dx.doi.org/10.15488/3396
eng
ISPRS Hannover Workshop: HRIGI 17 - CMRT 17 - ISA 17 - EuroCOW 17 : 6-9 June 2017, Hannover, Germany
ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences ; IV-1/W1
2194-9050
2194-9042
https://doi.org/10.5194/isprs-annals-IV-1-W1-99-2017
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/39312022-12-02T16:19:28Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:BookPartdoc-type:Textopen_accessddc:620ddc:520ddc:510
2018-10-30T14:54:12Z
urn:hdl:123456789/3931
Continuous Navigation of an Inland Vessel with a Synthetic GNSS Antenna
Kersten, Tobias
Ren, Le
Schön, Steffen
Navigation
GPS/GNSS antennas
Geodesy
radar engineering
inland vessel navigation
GPS/GNSS-Antennen
Navigation
Schiffsverkehr
Ortung
Radartechnik
Geodäsie
This paper describes a concept to obtain a continuous navigation and position solution of inland vessels based on a multi-GNSS antenna system. Also known as, “Virtual Receiver” we utilize this approach as an alternative method with respect to a common dead reckoning procedure. Such an approach strengthens the geometry of visible GNSS satellites immediatelyby up to 50%. At the same time, dilution of precision values improve by up to 40%. Hence, continuous navigation solution under difficult and challenging environmental conditions improves or is even possible. Specific experiments, obtained on a trip from Hannover westward on the Mittelland Canal with the inland vessel “MS Jenny” prove that various quality measures as well as the noise of the position estimates reduce significantly by up to 0.4 m. The position availability for code based navigation reaches 94.5% w.r.t classical single point positioning with 77%.
2018-10-30T14:54:12Z
2018-10-30T14:54:12Z
2018
BookPart
Text
Kersten, T.; Ren, L.; Schön, S.: Continuous Navigation of an Inland Vessel with a Synthetic GNSS Antenna. In: Proceedings of POSNAV ITS 2018, 15.-17. November 2018, Berlin. https://www.dgon-posnav.org
https://www.repo.uni-hannover.de/handle/123456789/3931
http://dx.doi.org/10.15488/3897
eng
Positionierung und Navigation für Intelligente Verkehrssysteme : POSNAV ITS 2018, Berlin, 15. - 17. November 2018 ; proceedings
https://doi.org/10.15488/4143
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
CC BY-NC-ND 3.0 DE
Bonn : DGON
oai:www.repo.uni-hannover.de:123456789/39322022-12-02T16:19:28Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:BookPartdoc-type:Textopen_accessddc:620ddc:520ddc:510
2018-10-30T14:59:51Z
urn:hdl:123456789/3932
A Virtual Receiver Concept for Continuous GNSS based Navigation of Inland Vessels
Kersten, Tobias
Ren, Le
Schön, Steffen
Navigation
GPS/GNSS antennas
inland vessel navigation
radar engineering
GNSS
Ortung
Schiffsverkehr
Navigation
Binnenschifffahrt
GPS/GNSS-Antennen
Efficient and economic guidance of inland vessels relies on a continuous, available, reliable and precise GNSS navigation solution. Hence, below other side effects, this is especially critical when passing beneath bridges or similar infrastructures that cross waterways. They have two effects: distortion (reflection, diffraction and interruption) of the incoming GNSS signal by the individual bridge structure on the one hand and along with that, the affected ambiguity resolution for carrier phase observation on the other hand. Thus, disturbances, discontinuities and jumps in the position estimates are present - an extreme critical situation especially for safety-relevant applications. A multi-antenna system for marine applications combined with the concept of a virtual receiver will be presented. This approach strengthen the overall geometry of visible GNSS satellites immediately, and provides continuous position estimates even for challenging passages. Furthermore, a bridging of observations between two or more antennas on a known rigid platform reduces signal interruptions and provides continuous navigation solution under challenging or even critical environmental conditions. Laboratory experiments, driven on a 2,5 hour turn from Hannover on the Mittelland Canal on the inland vessel MS Jenny (MS Science) prove, that various DOP values as well as noise of the position solution are reduced significantly. The observation noise is reduced by up to 0.3-0.4m whereby the position solution for a code based navigation reaches up to 94.5% w.r.t. classical single point positioning. The overall positioning performance is improved by up to 80%.
2018-10-30T14:59:51Z
2018-10-30T14:59:51Z
2018
BookPart
Text
Kersten, T.; Ren, L.; Schön, S.: A Virtual Receiver Concept for Continuous GNSS based Navigation of Inland Vessels. In: Proceedings of Navitec 2018, 5.-7. December 2018, Noordwijk, The Netherlands. http://navitec.esa.int/
https://www.repo.uni-hannover.de/handle/123456789/3932
http://dx.doi.org/10.15488/3898
eng
https://doi.org/10.15488/4142
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
CC BY-NC-ND 3.0 DE
Noordwijk, The Netherlands : Esa ESTEC
oai:www.repo.uni-hannover.de:123456789/39792022-12-02T18:18:52Zcom_123456789_1col_123456789_3ddc:550status-type:submittedVersiondoc-type:Textdoc-type:ConferenceObjectopen_accessddc:520
2018-11-15T08:02:57Z
urn:hdl:123456789/3979
Zur Bewertung von High Sensitivity GNSS-Empfängern bei der Kombination in Multi-Sensor-Systemen
Kersten, Tobias
Paffenholz, Jens-André
GPS/GNSS antennas
GPS/GNSS receiver
Navigation sensors
GPS
GNSS
terrestrial laser scanning
GPS/GNSS-Antennen
GPS/GNSS-Empfänger
Navigationssensoren
Terrestrisches Laserscanning
GPS
GNSS
Die instantan mit stationären, terrestrischen Laserscannern (TLS) aufgenommen dreidimensionalen Punktwolken beziehen sich generell auf ein lokales Horizontsystem, dessen Lage und Orientierung gegenüber einem übergeordnetem Koordinatensystem nur durch vorausberechnete Kontrollpunkte auf das notwendige geodätische Datum überführt werden können. Um eine direkte Georeferenzierung zu ermöglichen und den Prozess zu optimieren wurde am Geodätischen Institut Hannover (GIH) ein Multi-Sensor-System (MSS) entwickelt. Die aktuelle Konfiguration setzt sich aus kosteneffizienten und gewichtsreduzierten Elementen wie z.B. zwei Ublox M8T Empfängern in Kombination mit Ashtec L1-Antennen zusammen. Diese sind mit einer Basis von ca. 1 m auf dem Laserscanner aufgebracht und derart optimiert, dass das Sichtfeld nicht beeinflusst wird. Die anschließende Prozessierung zur Bestimmung der Transformationsparameter und des lokalen Azimuts basiert auf einen rekursiven Kalman Filter innerhalb eines Extended Kalman Filter (EKF) Ansatzes. Diese Systemkonfiguration und Auswertung führt nur zu optimalen Ergebnissen, sofern das Systemrauschen auf Ebene der originären Beobachtungen quantifiziert und exakt genau bekannt ist. Die Betrachtung auf der Beobachtungsebene erlaubt den Zugang zu den Beobachtungen, die durch modifizierte funktionale und stochastische Ansätze optimal angepasst werden können und steht damit im Gegensatz zu den Genauigkeitsparametern auf der Positionsebene, die sich aufgrund der internen Verarbeitung der Beobachtungen ergeben. Im Detail sind folgende Voraussetzungen notwendig: (1) es sollte eine Normalverteilung der Beobachtungen vorliegen, (2) die Informationen zur Kovarianzmatrix sollten vorhanden sein und (3) es sollten keine Korrelationen in zeitlicher Abhängigkeit entstehen. Diese Voraussetzungen sind aufgrund vorhandener stochastischer Abhängigkeiten durch zeitliche Korrelationen im Zustandsvektor nicht vollständig erfüllt. Zudem haben vorangegangene Studien gezeigt, dass die kinematischen Zeitreihen von ca. 15 Minuten Länge im Rahmen der Untersuchung der Autokorrelation zusätzliche Abhängigkeiten aufweisen. Daraufhin wurden in Kooperation mit dem Institut für Erdmessung (IfE) langzeitstatische Messungen bezüglich einer Referenzantenne auf einer Nullbasislinie analysiert und studiert, um die Systemeigenschaften der High-Sensitivity Empfänger zu quantifizieren und nachweisbare sowie robuste Aussagen für die Parameter der EFK-Modellierung ableiten zu können. Dieser Beitrag präsentiert ein Konzept zur Evaluierung und Analyse kosteneffizienter, high Sensitivity GNSS-Ausrüstungen. Es wird gezeigt, dass die Qualität dieser Geräte für eine breite Variation von Anwendungen erheblich gute Performanz aufweist, z. B. liegt das Trägerphasenrauschen bei 2 mm im Zenitbereich und ist damit vergleichbar zu aktuellen geodätischen GNSS-Empfängern. Dennoch ergeben sich marginale Elevationsabhängigkeiten, die es zusätzlich zu berücksichtigen gilt. Die wichtigsten Testparameter für den vorgestellten Ansatz sind u.a. die Trägerphasenstabilität, das Rauschniveau sowie Inter-Frequenz Offsets. Mit Werkzeugen wie z. B. der Quantil-/Quantil-Darstellung oder der Allan-Standardabweichung lassen sich die Rauschtypen charakterisieren. Zusätzlich erlaubt eine Analyse der Allan-Standardabweichung einen Rückschluss auf die Kurz- und Langzeitstabilität aller Beobachtungstypen (Träger-, Codephase, Doppler und C/N0) solcher Geräte. Zur Kreuzvalidierung werden zusätzlich Ergebnisse kinematischer Analysen diskutiert. Eine stabile Lösung im Sinne des Ansatzes einer kinematischen Basislinie für die zwei Antennen auf dem Scanner stehen im Fokus der aktuellen Betrachtungen. Die Ergebnisse und Quantifizierungen sollen zukünftig unterstützend helfen, Systemeigenschaften von Multi-Sensor-Systemen optimal abstimmen und Anwendungsfelder von High-Sensitivity Empfängern gesichert abschätzen zu können.
2018-11-15T08:02:57Z
2018-11-15T08:02:57Z
2018-11-16
ConferenceObject
Text
Kersten, T.; Paffenholz, J.-A.: Zur Bewertung von High Sensitivity GNSS-Empfängern bei der Kombination in Multi-Sensor-Systemen. Poster Präsentation, POSNAV ITS 2018. https://www.dgon-posnav.org
https://www.repo.uni-hannover.de/handle/123456789/3979
http://dx.doi.org/10.15488/3945
ger
Positionierung und Navigation für Intelligente Verkehrssysteme : POSNAV ITS 2018, Berlin, 15. - 17. November 2018 ; proceedings
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
CC BY-NC-ND 3.0 DE
Bonn : DGON
oai:www.repo.uni-hannover.de:123456789/40332022-12-02T16:19:28Zcom_123456789_1col_123456789_3status-type:submittedVersiondoc-type:BookPartdoc-type:Textopen_accessddc:620ddc:520
2018-11-21T10:05:36Z
urn:hdl:123456789/4033
Receiver Antenna Phase Center Models and Their Impact on Geodetic Parameters
Kersten, Tobias
Schön, Steffen
Carrier phase centre variation (PCV)
Generic patterns
GNSS
GNSS antennas
Evaluating the impact of receiver antenna phase centre corrections (PCCs) in geodetic positioning and timing applications in a general way is quite challenging, because several estimation concepts, implementation philosophies as well as different sets of PCCs exist and interact with each other and their contributions are not identifiable. In this paper, the authors present a methodology, based on investigations of Geiger (GPS-techniques applied to geodesy and surveying. Lecture notes in earth sciences, vol 19. Springer, New York, pp 210–222, 1988) and Santerre (Manuscr Geodaet 16:28–53, 1991), to classify PCCs and forecast their impact on all geodetic parameters, i.e. not only the position but also the receiver clock and troposphere parameter in a phase based precise point positioning (PPP) approach. In a first step, we introduce the mathematical model and generic PCC patterns. In the second step, simulation studies are carried out. Findings are evaluated by empirical studies using differences of PPP results to isolate the impact of different patterns. In parallel, the software impact is analysed since every software handles the observation modelling and parameter estimation differently, e.g., Kalman filter versus least squares approach. We show that all geodetic parameters are affected by PCC and that the impact on the parameters can be even amplified compared to the magnitude of the generic patterns. The final publication is available at Springer via https://doi.org/10.1007/1345_2016_233.
2018-11-21T10:05:36Z
2018-11-21T10:05:36Z
2016
BookPart
Text
Kersten, T. & Schön, S.: Receiver Antenna Phase Center Models and Their Impact on Geodetic Parameters. In: Freymueller, J.T.; Sánchez, L. (Eds): International Symposium on Earth and Environmental Sciences for Future Generations. Berlin : Springer, 2016 (IAG Symposia ; 147), S. 253-259. DOI: https://doi.org/10.1007/1345_2016_233
https://www.repo.uni-hannover.de/handle/123456789/4033
http://dx.doi.org/10.15488/3999
eng
Freymueller J.T., Sánchez L. (Eds) International Symposium on Earth and Environmental Sciences for Future Generations
IAG SYMPOSIA;147
https://doi.org/10.15488/4563
978-3-319-69169-5
10.1007/1345_2016_233
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Cham : Springer
oai:www.repo.uni-hannover.de:123456789/40342022-12-02T16:19:28Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:BookPartdoc-type:Textopen_accessddc:620ddc:520
2018-11-21T10:14:40Z
urn:hdl:123456789/4034
Antenna specific IfE-robot based code phase delays and its impact on positioning and navigation
Kersten, Tobias
Schön, Steffen
phase center variations (PCV)
GNSS
Group Delay Variations (GDV)
The Institut für Erdmessung (IfE) is an official IGS calibration institution, calibrating phase center variations (PCV) for receiver antennae routinely in the field, using the actual GNSS satellite signals in space. Current research activities focus on the antenna code phase calibration with the Hannover Concept of absolute antenna calibration. The receiving antenna as a part of a reception chain can introduce systematic effects, currently known as Group Delay Variations (GDV), i.e. azimuth and elevation dependent code-phase delays. This error introduces additional range variations along the line-of-sight for every satellite depending on the corresponding incident angle in the antennas body frame. Depending on the antenna design, suitable for specific applications, GDV can degrade the accuracy of code based applications, such as precise landing approaches as well as for time and frequency transfer. The paper can be subdivided into two major parts: In the first part, we focus on the current investigations on receiver antenna GDV calibration. Beside the theoretical background of a concept to determine GDV for different GPS antennae based on the Hannover Concept of absolute antenna calibration, the obtained GDV from several antennae with different characteristics will be presented and critically discussed. The second part focuses on the consequent analysis of the impact of the determined GDV on position and navigation applications. The contribution of GDV on the observation and position domain can be shown by using a special experimental set-up. In addition, GDV for a real C/A based autonomous navigation approach are investigated and critically discussed. © 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
2018-11-21T10:14:40Z
2018-11-21T10:14:40Z
2012
BookPart
Text
Kersten, T. & Schön, S.: Antenna specific IfE-robot based code phase delays and its impact on positioning and navigation. In: Proceedings of the 2012 6th ESA Workshop on Satellite Navigation Technologies (Navitec 2012) & European Workshop on GNSS Signals and Signal Processing 2012, 8 S. DOI: https://doi.org/10.1109/NAVITEC.2012.6423088
https://www.repo.uni-hannover.de/handle/123456789/4034
http://dx.doi.org/10.15488/4000
eng
2012 6th ESA Workshop on Satellite Navigation Technologies (Navitec 2012) & European Workshop on GNSS Signals and Signal Processing
10.1109/NAVITEC.2012.6423088
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Piscataway, NJ : IEEE
oai:www.repo.uni-hannover.de:123456789/40352022-12-02T18:18:52Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:Textdoc-type:ConferenceObjectopen_accessddc:620ddc:520
2018-11-21T10:22:43Z
urn:hdl:123456789/4035
On the impact of Group Delay Variations on GNSS time and frequency transfer
Kersten, Tobias
Schön, Steffen
Weinbach, Ulrich
GNSS
Group Delay Variations (GDV)
Precise Point Positioning (PPP)
Group Delay Variations (GDVs) are azimuth and elevation dependent code delays that can limit the accuracy of the GNSS code observables. This contribution focuses on the GDV determination and discusses several solutions with respect to repeatability and separability. On-site tests at a laboratory network as well as simulations of several time links are discussed analyzing the stochastic processes apparently introduced by GDV. The stability of the P3 links are not effected. However, offsets up to 0.6 ns can occur. In a detailed study, GDVs are applied to an inter-continental Precise Point Positioning (PPP) time transfer link. This analysis shows that GDV are not an issue for the stability of the PPP links, since small weights reduce the impact of the P3 GDV. It can be shown that the stochastic process, induced by GDV in a PPP analysis, is similar to a random walk noise, well below the L3 carrier phase observation noise of σ φ = 6 mm. Offsets for the receiver clock estimates of up to 0.4 ns are reported for the link WTZS (Wettzell) and Boulder (NIST). © 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
2018-11-21T10:22:43Z
2018-11-21T10:22:43Z
2012
ConferenceObject
Text
Kersten, T.; Schön, S.; Weinbach, U.: On the impact of Group Delay Variations on GNSS time and frequency transfer. In: Proceedings of the 2012 European Frequency and Time Forum, S. 514-521. DOI: https://doi.org/10.1109/EFTF.2012.6502435
https://www.repo.uni-hannover.de/handle/123456789/4035
http://dx.doi.org/10.15488/4001
eng
Proceedings of the 2012 European Frequency and Time Forum
978-1-4673-1923-2
10.1109/EFTF.2012.6502435
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Piscataway, NJ : IEEE
oai:www.repo.uni-hannover.de:123456789/40362022-12-02T16:19:28Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:BookPartdoc-type:Textopen_accessddc:620ddc:520
2018-11-21T10:28:28Z
urn:hdl:123456789/4036
Towards modeling phase center variations for multi-frequency and multi-GNSS
Kersten, Tobias
Schön, Steffen
Phase Center Variations (PCV)
GNSS
multi-system-calibration
With the Hannover concept of absolute field calibration of GNSS antennae the determination of receiver antenna Phase Center Variations (PCV) can be done routinely for the GPS and GLONASS L1 and L2 frequencies, respectively. The need of multi-GNSS and multi-frequency applications - demanded by a broader navigation community - tends to a combined estimation of receiver antenna depending properties for various frequencies and systems. This approach is only advantageous if inter-frequency and inter-system biases are known and continuously considered. In this contribution we investigate steps towards a concept for multi-system-calibration. After a short introduction to the absolute field calibration procedure, the mathematical model as well as adjustment concept will be presented. We show that test results suggest that the receiver demodulation may have an impact on the estimated PCV. The correlation analysis of the multi-frequency multi-GNSS approach underlines that (1) the correct consideration of the mathematical correlations between the parameters to up to 25%, (2) The receiver clock links the results from different frequencies and (3) PCV for different GNSS systems can be computed in a common adjustment since the inter-system correlations are below 1-2%. © 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
2018-11-21T10:28:28Z
2018-11-21T10:28:28Z
2010
BookPart
Text
Kersten, T. & Schön, S.: Towards modeling phase center variations for multi-frequency and multi-GNSS. In: Proceedings of the 2010 5th ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing (NAVITEC). Piscataway : IEEE, 2010, 8 S. DOI: https://doi.org/10.1109/NAVITEC.2010.5708040
https://www.repo.uni-hannover.de/handle/123456789/4036
http://dx.doi.org/10.15488/4002
eng
Proceedings of the 2010 5th ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing (NAVITEC)
978-1-4244-8739-4
10.1109/NAVITEC.2010.5708040
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Piscataway, NJ : IEEE
oai:www.repo.uni-hannover.de:123456789/40782022-12-02T19:19:56Zcom_123456789_15col_123456789_18doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2018-11-27T08:24:33Z
urn:hdl:123456789/4078
Detecting Binary Compact-object Mergers with Gravitational Waves: Understanding and Improving the Sensitivity of the PyCBC Search
Nitz, Alexander H.
Dent, Thomas
Dal Canton, Tito
Fairhurst, Stephen
Brown, Duncan A.
black hole physics
gravitational waves
stars: neutron
We present an improved search for binary compact-object mergers using a network of ground-based gravitational wave detectors. We model a volumetric, isotropic source population and incorporate the resulting distribution over signal amplitude, time delay, and coalescence phase into the ranking of candidate events. We describe an improved modeling of the background distribution, and demonstrate incorporating a prior model of the binary mass distribution in the ranking of candidate events. We find an ∼10% and ∼20% increase in detection volume for simulated binary neutron star and neutron star black hole systems, respectively, corresponding to a reduction of the false alarm rates assigned to signals by between one and two orders of magnitude.
2018-11-27T08:24:33Z
2018-11-27T08:24:33Z
2017
Article
Text
Nitz, A.H.; Dent, T.; Dal, Canton, T.; Fairhurst, S.; Brown, D.A.: Detecting Binary Compact-object Mergers with Gravitational Waves: Understanding and Improving the Sensitivity of the PyCBC Search. In: Astrophysical Journal 849 (2017), Nr. 2, 118. DOI: https://doi.org/10.3847/1538-4357/aa8f50
https://www.repo.uni-hannover.de/handle/123456789/4078
http://dx.doi.org/10.15488/4044
eng
Astrophysical Journal 849 (2017), Nr. 2
0004-637X
https://doi.org/10.3847/1538-4357/aa8f50
https://creativecommons.org/licenses/by/3.0/
CC BY 3.0 Unported
Bristol : Institute of Physics Publishing
oai:www.repo.uni-hannover.de:123456789/41772022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520ddc:510
2018-12-10T06:30:15Z
urn:hdl:123456789/4177
Continuous Navigation of an Inland Vessel with a Synthetic GNSS Antenna
Kersten, Tobias
Ren, Le
Schön, Steffen
inland vessel navigation
GPS/GNSS antennas
navigation
GPS/GNSS Antennen
Ortung
Navigation
Schiffsnavigation
Binnenschiffahrt
This paper describes a concept to obtain a continuous navigation and position solution of inland vessels based on a multi-GNSS antenna system. Also known as, “Virtual Receiver” we utilize this approach as an alternative method with respect to a common dead reckoning procedure. Such an approach strengthens the geometry of visible GNSS satellites immediatelyby up to 50%. At the same time, dilution of precision values improve by up to 40%. Hence, continuous navigation solution under difficult and challenging environmental conditions improves or is even possible. Specific experiments, obtained on a trip from Hannover westward on the Mittelland Canal with the inland vessel “MS Jenny” prove that various quality measures as well as the noise of the position estimates reduce significantly by up to 0.4 m. The position availability for code based navigation reaches 94.5% w.r.t classical single point positioning with 77%.
2018-12-10T06:30:15Z
2018-12-10T06:30:15Z
2018-11-15
ConferenceObject
Text
Kersten, T.; Ren, L.; Schön, S.: Continuous Navigation of an Inland Vessel with a Synthetic GNSS Antenna. In: Proceedings of POSNAV ITS (2018), 15.-17. November 2018, Berlin. https://www.dgon-posnav.org
https://www.repo.uni-hannover.de/handle/123456789/4177
http://dx.doi.org/10.15488/4143
eng
Proceedings of POSNAV ITS 2018, 15.-17. November 2018, Berlin
https://doi.org/10.15488/3897
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
CC BY-NC-ND 3.0 DE
Bonn : DGON
oai:www.repo.uni-hannover.de:123456789/44922022-12-02T18:18:52Zcom_123456789_1col_123456789_3status-type:submittedVersiondoc-type:Textdoc-type:ConferenceObjectopen_accessddc:520
2019-02-22T06:30:50Z
urn:hdl:123456789/4492
IfE monthly gravity field solutions using the variational equations
Naeimi, Majid
Koch, Igor
Khami, Arman
Flury, Jakob
LUH-GRACE2018
GRACE Satellite
Time-Variable Earth's Gravity Field
LUH-GRACE2018
GRACE Satellit
Schwerkraftfeld
In this contribution, we present the LUH-GRACE2018 monthly gravity field solutions from GRACE-KBR measurements, which produced at Institut für Erdmessung (IfE) at Leibniz University of Hannover. Our solutions, based on the classical variational approach, are obtained in two processing steps. In the first step, the orbits of both satellites are dynamically integrated and the initial state vectors together with accelerometer bias parameters of both satellites are adjusted using GRACE L1B reduced dynamic orbit. In the second step the 6-hourly-arc normal equations are accumulated and the monthly gravity field spherical coefficients up to degree and order 80 are estimated along with the unknown parameters of step 1. The geoid degree standard deviations of our solutions show a very good agreement with the official solutions of CSR, GFZ and JPL. The differences are well below 0.1 of an order of magnitude indicating the success of our implementation. Details of processing steps and the mass variations derived from our solutions are presented.
2019-02-22T06:30:50Z
2019-02-22T06:30:50Z
2018-04-13
ConferenceObject
Text
Naeimi, M.; Koch, I.; Khami, A.; Flury, J.: IfE monthly gravity field solutions using the variational equations. EGU General Assembly 2018, 8.-13. April 2018, Vienna, Austria
https://www.repo.uni-hannover.de/handle/123456789/4492
http://dx.doi.org/10.15488/4452
eng
https://meetingorganizer.copernicus.org/EGU2018/EGU2018-1516-1.pdf
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Hannover : Institutionelles Repositorium der Leibniz Universität Hannover
oai:www.repo.uni-hannover.de:123456789/45962022-12-13T15:14:00Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-03-25T12:46:01Z
urn:hdl:123456789/4596
Performance of different filters for determining temporal mass variations from GRACE in the Siberian permafrost region
Shabanloui, Akbar
Müller, Jürgen
Filter performance analyse
Siberia permafrost
GRACE Level 2 products
Filter Performanceanalyse
Siberian Permafrostgebiet
GRACE Level 2 Produkte
Based on GRACE (Gravity Recovery and Climate Experiment) measurements, mass variations in different regions of the Earth can be determined with different temporal-spatial resolution. Permafrost in Siberia (Russia) is one of the challenging phenomena in the context of climate warming. Therefore, the precise estimation of temporal mass variations in this region based on the GRACE monthly solutions of different data analysis centres plays a key role to better understand the complex processes. Temporal mass variations in this region are mainly related to hydrological processes including thawing of permafrost layers. GRACE monthly gravity solutions suffer from the correlation of spherical harmonic coefficients (that causes stripping effects in North-South direction) and from less accuracy of the short wavelengths of the Earth’s gravitational representation coefficients. Therefore designing efficient filters for de-correlating Stokes coefficients is indispensable in the post-processing of GRACE monthly solutions. It should be mentioned, filters improve the resolution, but they also remove signal parts in the results. In this study, different filters (e.g. the Gaussian filters with different radii, DDK filters, etc.) are applied to the new Release 5 of the monthly gravity solutions from different analysis centres to extract mass variations in Siberia and consequently to help quantifying permafrost-related contributions.
2019-03-25T12:46:01Z
2019-03-25T12:46:01Z
2014-04-27
ConferenceObject
Text
Shabanloui, A.; Müller, J.: Performance of different filters for determining temporal mass variations from GRACE in the Siberian permafrost region. EGU General Assembly (2014), EGU2014-3662
https://www.repo.uni-hannover.de/handle/123456789/4596
http://dx.doi.org/10.15488/4554
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
München : European Geosciences Union
oai:www.repo.uni-hannover.de:123456789/45972022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-03-25T13:18:36Z
urn:hdl:123456789/4597
Mass variations in the Siberian permafrost region based on new GRACE results and auxiliary modeling
Shabanloui, Akbar
Müller, Jürgen
Mass variations from GRACE Data
Mass distribution
hydrological model
Auxiliary modeling
Massenvariationen aus GRACE-Daten
Massenverteilung
Hydrologisches Modell
Siberian Permafrostgebiet
GRACE (Gravity Recovery and Climate Experiment) determines the integral mass variations in the Earth system with different spatial-temporal resolution. These mass variations should be adequately separated for better understanding of the single signal contributions. In Siberia, the temporal mass variations are related to hydrological processes including thawing of huge permafrost layers. The permafrost layers with different thicknesses cover about 80% of Siberia. Therefore these frozen sheets play an important role for sea level rise and the hydrological water cycle. In this study, the integral mass variations in Siberia are precisely estimated based on the new release of GRACE from GFZ (RL05a). On the other hand, various hydrological contributions (lake level variation, river runoff, etc.) can be estimated from different models and specific data. Here, mass variations in the Siberian permafrost region based on GRACE results and different hydrological models/data will be jointly investigated.
2019-03-25T13:18:36Z
2019-03-25T13:18:36Z
2014-06-30
ConferenceObject
Text
Shabanloui, A.; Müller, J.: Mass variations in the Siberian permafrost region based on new GRACE results and auxiliary modeling. 3rd International gravity field Service (IGFS) Meeting (2014). http://202.127.29.4/meetings/igfs2014/
https://www.repo.uni-hannover.de/handle/123456789/4597
http://dx.doi.org/10.15488/4555
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/45982022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-03-25T13:22:53Z
urn:hdl:123456789/4598
Constraining mass variations in the Siberian permafrost region based on GRACE and Satellite Altimetry
Shabanloui, Akbar
Müller, Jürgen
Mass variations from GRACE Level 2 Products
Satellite Altimetry
Siberia Permafrost region
Massenvariationen aus GRACE Level2 Produkten
Massenverteilung
Satellitengravimetrie
Satelliten-Altimetrie
Siberian Permafrostgebiet
The permafrost layers in the Siberia (Russia) with different thicknesses cover about 80% of this region. Therefore these frozen sheets play an important role for the hydrological water cycle of the Earth system. The integral mass variations in the Earth system with different spatial-temporal resolution are determined based on GRACE observations/products. On the one hand, the mass variations in this region are precisely estimated based on the new release of GRACE Level 2 products from GFZ (RL05a). On the other hand, these (hydrological) mass variations can be geometrically determined based on satellite (radar/laser) altimetry tracking data. The mass variations in this region are extracted from lake (see) level variations that observed by satellite altimetry missions (e.g. Jason-2, ICESat). In this investigation, the mass variations in the Siberian region that concluded from satellite altimetry missions are used to constrain hydrological mass variations from GRACE mission. This sort of constraining results should present a realistic mass transport pattern.
2019-03-25T13:22:53Z
2019-03-25T13:22:53Z
2014-10-07
ConferenceObject
Text
Shabanloui, A.; Müller, J.: Constraining mass variations in the Siberian permafrost region based on GRACE and Satellite Altimetry. Geodätische Woche (2014). https://www.geodaetische-woche.de/
https://www.repo.uni-hannover.de/handle/123456789/4598
http://dx.doi.org/10.15488/4556
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/45992022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-03-25T14:31:39Z
urn:hdl:123456789/4599
Assimilation of GRACE, satellite Altimetry and Hydrological data for determining mass variations in the Siberian permafrost region
Shabanloui, Akbar
Müller, Jürgen
Assimilation of GRACE
satellite altimetry and hydrological data
mass variations
Permafrost region of Siberia
Assimilation von GRACE
Satellitenaltimetrie und hydrologischen Daten
Massenvariationen
sibirisches Permafrostgebiet
The permafrost in Siberia (Russia) plays an important role for the global water cycle and climate change in the Earth system. In this study, data from satellite altimetry missions, hydrological models and GRACE are assimilated to retrieve a more realistic pattern of surface mass variations in Siberia. GRACE provides the integral mass variations with different spatial-temporal resolution depending on the applied filters and reduction models. We used the new release L2 products from GFZ (RL05a) and tested various filters. Geometrically, surface mass variations are determined based on satellite (radar/laser) altimetry tracking data (e.g. Jason-2, ICESat), where especially lake level variations are extracted. In addition, hydrological surface mass variations are obtained from hydrological water cycle models based on observations of precipitation, evapotranspiration and run-off data. We tried to quantify the individual signal contributions in Siberia and to consistently combine the various data to get a better estimate on how big the real permafrost change might be.
2019-03-25T14:31:39Z
2019-03-25T14:31:39Z
2014
ConferenceObject
Text
Shabanloui, A.; Müller, J.: Assimilation of GRACE, satellite Altimetry and Hydrological data for determining mass variations in the Siberian permafrost region. GRACE Science Team Meeting 2014
https://www.repo.uni-hannover.de/handle/123456789/4599
http://dx.doi.org/10.15488/4557
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/46002022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-03-25T14:43:19Z
urn:hdl:123456789/4600
How reliable is the mass variation in the Siberian permafrost region as observed by GRACE mission?
Shabanloui, Akbar
Müller, Jürgen
reliability of mass variations
Siberian permafrost region
Satellite mission GRACE
Satellitengestütze Gravimetrie
GRACE
sibirisches Permafrostgebiet
Zuverlässigkeit der Massenvariationen aus Satellitenmission GRACE
Permafrost generally and in Siberia (Russia) especially plays a key role for global hydrological mass transport, climate change and the eco-system of the Earth. In this study, surface and sub-surface mass variations in the Siberian permafrost region based on the gravitational approach (i.e. from GRACE mission) are estimated, and investigated to what extent the mass transport estimates are reliable and realistic. On the other hand, hydrological mass variations in this region are determined based on the geometrical approach using satellite (radar/laser) altimetry re-tracking data (e.g. Jason-2, ICESat) and satellite imagery (e.g. LandSat). In addition, hydrological surface mass variations are extracted from global hydrological water cycle models based on various in-situ hydrological observations, e.g. precipitation, evapotranspiration and run-off data. In this study, we quantify and asses the signal errors and its contributions to the integral mass variations in Siberia including error bars and determine to what extent GRACE results can provide mass variations which are caused by permafrost changes.
2019-03-25T14:43:19Z
2019-03-25T14:43:19Z
2015-09-20
ConferenceObject
Text
Shabanloui, A.; Müller, J.: How reliable is the mass variation in the Siberian permafrost region as observed by GRACE mission?. GEOQuebec (2015). http://www.geoquebec2015.ca/
https://www.repo.uni-hannover.de/handle/123456789/4600
http://dx.doi.org/10.15488/4558
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/46022022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-03-26T10:19:12Z
urn:hdl:123456789/4602
Study of an optical gradiometer for future satellite gravitational missions
Douch, Karim
Müller, Jürgen
Brieden, Phillip
Shabanloui, Akbar
Optical Gradiometer
Future Satellite Mission
Optische Gradiometer
zukünftige Satellitenmission
Monitoring the static and time-variable gravitational field based on new optical gradiometer based on interferometeric techniques is studied.
2019-03-26T10:19:12Z
2019-03-26T10:19:12Z
2015-09-17
ConferenceObject
Text
Douch, K.; Müller, J.; Brieden, P.; Shabanloui, A.: Study of an optical gradiometer for future satellite gravitational missions. Geodätische Woche (2015). https://www.geodaetische-woche.de/
https://www.repo.uni-hannover.de/handle/123456789/4602
http://dx.doi.org/10.15488/4560
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/46032022-12-02T18:24:34Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:Reportdoc-type:Textopen_accessddc:620ddc:520
2019-03-26T10:23:41Z
urn:hdl:123456789/4603
How reliable is the mass variation in the Siberian permafrost region as observed by GRACE?
Shabanloui, Akbar
Müller, Jürgen
Mass variations from GRACE Level2 products
Reliability of GRACE results
Massenvariationen aus GRACE Level2 Produkten
Massenverteilung
Siberian Permafrostgebiet
Zuverlässigkeit der GRACE Ergebnisse
Permafrost generally and in Siberia (Russia) especially plays a key role for global hydrological mass transport, climate change and the eco-system of the Earth. In this study, surface and sub-surface mass variations in the Siberian permafrost region based on the gravitational approach (i.e. from GRACE mission) are estimated, and investigated to what extent the mass transport estimates are reliable and realistic. On the other hand, hydrological mass variations in this region are determined based on the geometrical approach using satellite (radar/laser) altimetry re-tracking data (e.g. Jason-2, ICESat) and satellite imagery (e.g. LandSat). In addition, hydrological surface mass variations are extracted from global hydrological water cycle models based on various in-situ hydrological observations, e.g. precipitation, evapotranspiration and run-off data. In this study, we quantify and asses the signal errors and its contributions to the integral mass variations in Siberia including error bars and determine to what extent GRACE results can provide mass variations which are caused by permafrost changes.
2019-03-26T10:23:41Z
2019-03-26T10:23:41Z
2015-09-20
Report
Text
Shabanloui, A.; Müller, J.: How reliable is the mass variation in the Siberian permafrost region as observed by GRACE?. GEOQuebec 2015. http://www.geoquebec2015.ca/
https://www.repo.uni-hannover.de/handle/123456789/4603
http://dx.doi.org/10.15488/4561
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/46042022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-03-26T10:26:53Z
urn:hdl:123456789/4604
Präzise Satellitenbahnmodellierung am Beispiel der neuen Swarm-Mission
Koch, Igor
Alpers, Peter
Bashi, Mahsa
Flury, Jakob
Kröhnert, Damian
Naeimi, Majid
Schilling, Manuel
Shabanloui, Akbar
Precise Satellite Orbit Modeling
Swarm mission
Präzise Satellitenbahnmodellierung
Swarm-Mission
Präzise Satellitenbahnmodellierung am Beispiel der neuen SWARM-Mission
2019-03-26T10:26:53Z
2019-03-26T10:26:53Z
2015-09-15
ConferenceObject
Text
Koch, I. et al.: Präzise Satellitenbahnmodellierung am Beispiel der neuen Swarm-Mission. Geodätische Woche (2015). https://www.geodaetische-woche.de/
https://www.repo.uni-hannover.de/handle/123456789/4604
http://dx.doi.org/10.15488/4562
ger
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/46052022-12-02T18:18:52Zcom_123456789_1col_123456789_3ddc:550doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-03-26T10:31:47Z
urn:hdl:123456789/4605
Impact of antenna phase center models: From observation to parameter domain
Kersten, Tobias
Hiemer, Leonard
Schön, Steffen
GPS/GNSS antennas
GNSS receiver antenna calibration
Carrier phase centre variation (PCV)
uncertainty
GPS/GNSS-Antennen
Trägerphasen-Variationen (PCV)
Unischerheiten
GPS/GNSS-Empfänger
GPS/GNSS-Antennenkalibrierung
For precise GNSS applications like positioning, navigation and timing (PNT) as well as for troposphere studies, stable and accurate calibrations of the carrier phase center variations (PCV) for individual antennas have to be provided by calibration institutions. Beside an anechoic chamber calibration, the Institut für Erdmessung (IfE) uses a field approach with a precisely calibrated robot. Ring analyses between different calibration institutions determined with geodetic graded antennas show comparability at the level of 1mm which is a threshold accepted by the International GNSS Service (IGS).
Several contributions and papers discuss the impact of the variability of calibration models on the coordinate or parameter domain, respectively. This can only be a first approximation since complex interactions depending on the processing philosophy, propagates PCVs differently to the parameters, so that unexpected discrepancies on the parameter domain can occur and have to be analysed consequently.
This contribution presents a concept to study the impact of PCVs on the observation and parameter domain. In this concept the PCVs will be formulated not as classical tabulated PCV models but with their corresponding spherical harmonic (SH) coefficients. Finding a transfer function to analytically study the impact of the PCVs on the individual parameter like i.e. coordinates, time and troposphere as well as ambiguities is one of the three main goals in this concept. Exemplarily we will show first results and will study error functions between type and individual calibration models based on the proposed concept.
2019-03-26T10:31:47Z
2019-03-26T10:31:47Z
2015-06-25
ConferenceObject
Text
Kersten, T.; Hiemer, L.; Schön, S.: Impact of antenna phase center models: From observation to parameter domain. 26th IUGG General Assembly (2015)
https://www.repo.uni-hannover.de/handle/123456789/4605
http://dx.doi.org/10.15488/4563
eng
26th International Union of Geodesy and Geophysics (IUGG)
https://doi.org/10.15488/3999
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
CC BY-NC-ND 3.0 DE
Prague : IUGG
oai:www.repo.uni-hannover.de:123456789/46622022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-03-28T06:19:30Z
urn:hdl:123456789/4662
The impact of regional meteorological network data on AOD1B products
Yan, Yihao
Shabanloui, Akbar
Flury, Jakob
Zhong, Ming
Xu, Houze
GRACE de-aliasing products
regional meteorological network
AOD1B products
GRACE de-aliasing Produkte
regionale meteorlogische Netzwerk
AOD1B Produkte
The AOD1B products show the short-term variations of gravity field and are removed from satellite observations in the post-processing step known as de-aliasing. The meteorological networks play an important role in the calculation of AOD1B products. In this work, the first step is to analysis the differences between standard Numerical Weather Prediction (NWP) models, e.g. European ECMWF model (ERA-40, ERA-Interim and operational) and US NCEP model. In the second step, we assess the effect of Chinese regional meteorological network data on the global NWP models. The Chinese regional meteorological network consists of 2170 stations, and the correctness of the dataset is verified by quality control on the ground. Finally, we assess the effect of regional meteorological network on AOD1B products by evaluating GRACE KBRR residuals.
2019-03-28T06:19:30Z
2019-03-28T06:19:30Z
2018-04-04
ConferenceObject
Text
Yan, Y.; Shabanloui, A.; Flury, J.; Zhong, M.; Xu, H.: The impact of regional meteorological network data on AOD1B products. EGU General Assembly (2018)
https://www.repo.uni-hannover.de/handle/123456789/4662
http://dx.doi.org/10.15488/4620
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/46952022-12-02T18:18:52Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:Textdoc-type:ConferenceObjectopen_accessddc:530ddc:520
urn:hdl:123456789/4695
Deficiencies of Phase Centre Models: Assessing the impact on geodetic parameters
Kersten, Tobias
Kröger, Johannes
Breva, Yannick
Schön, Steffen
GPS/GNSS antennas
GNSS
GPS/GNSS receiver
Geodesy
GPS/GNSS-Antennen
GNSS
GPS/GNSS-Empfänger
Geodäsie
Precise GNSS applications like positioning, navigation and timing (PNT) as well as troposphere studies require consistent and accurate calibration values of receiver antennas. Nowadays, they are available by several calibration institutions based on robot or anechoic chamber concepts. The impact of phase centre model of receiver antennas on geodetic parameters like position, troposphere and receiver clock estimates is quite challenging as several estimation concepts, implementation philosophies and different phase centre models exist. Their interaction with the estimates is complex, their individual impact not easily identifiable and a concept to forecast the impact on associated geodetic parameters not available at present.
To integrate new satellite systems in the operational service, station operators of global (IGS) regional (EPN) and national (e.g. SAPOS, Germany or similar) networks require calibration values of these new signals in space (i.e. GPS L5, Galileo, etc). They are currently provided by chamber calibrations. However, the most of operational networks are mainly equipped with robot calibrations for GPS/GLONASS L1/L2. Although deficiencies exist for individual antennas between chamber and robot, a mixture of calibration values is applied to overcome the issue of required and available phase centre corrections. Nevertheless, differences will introduce systematic discrepancies in the parameters. At present, a rule of thumb for phase centre corrections to compare chamber and robot calibrations applies, which does not directly take into account the impact on the associated geodetic parameters. In addition, discrepancies between type mean and individual calibrations of up to 6-8mm are reported in regional and global networks, which lead up to 10mm in the height and up to 4mm in the horizontal component.
This contribution will present a methodology to clarify this issue and will provide a concept to verify parameters, e.g. position, receiver clock and troposphere estimates. In previous publications, the authors focus on generic patterns to determine characteristics between chamber and robot calibrations. In this contribution, we verify the impact and apply stations of the EPN network, which provide equipment with calibrations of both types. Hence, a quantification of the impact is required to answer the following question: Is the 1mm-rule of thumb is justified, or are there better thresholds available to assist station operators in the near future?
2019-03-28T10:55:32Z
2019-04-08
ConferenceObject
Text
Kersten, T. et al.: Deficiencies of Phase Centre Models: Assessing the impact on geodetic parameters. In: Geophysical Research Abstracts 21 (2019), EGU2019-10153-1
https://www.repo.uni-hannover.de/handle/123456789/4695
http://dx.doi.org/10.15488/4653
eng
EGU General Assembly
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
CC BY-NC-ND 3.0 DE
München : European Geosciences Union
oai:www.repo.uni-hannover.de:123456789/46802022-12-02T19:19:56Zcom_123456789_15col_123456789_18doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-03-28T10:21:31Z
urn:hdl:123456789/4680
Novel active driven drop tower facility for microgravity experiments investigating production technologies on the example of substrate-free additive manufacturing
Lotz, Christoph
Wessarges, Yvonne
Hermsdorf, Jörg
Ertmer, Wolfgang
Overmeyer, Ludger
Additive manufacturing
Drop tower
Laser beam melting (LBM)
Laser metal deposition (LMD)
Linear motor
Microgravity and hypogravity
3D printers
Industrial research
Laser beams
Linear motors
Manufacture
Microgravity
Microgravity processing
Drop towers
Drop-tower facility
High repetition rate
Laser beam melting
Laser metal deposition
Microgravity experiments
Production process
Production technology
Substrates
Through the striving of humanity into space, new production processes and technologies for the use under microgravity will be essential in the future. Production of objects in space demands for new processes, like additive manufacturing. This paper presents the concept and the realization for a new machine to investigate microgravity production processes on earth. The machine is based on linear long stator drives and a vacuum chamber carrying up to 1000 kg. For the first time high repetition rate and associated low experimental costs can provide basic research. The paper also introduces the substrate-free additive manufacturing as a future research topic and one of our primary application.
2019-03-28T10:21:31Z
2019-03-28T10:21:31Z
2018
Article
Text
Lotz, C.; Wessarges, Y.; Hermsdorf, J.; Ertmer, W.; Overmeyer, L.: Novel active driven drop tower facility for microgravity experiments investigating production technologies on the example of substrate-free additive manufacturing. In: Advances in Space Research 61 (2018), Nr. 8, S. 1967-1974. DOI: https://doi.org/10.1016/j.asr.2018.01.010
https://www.repo.uni-hannover.de/handle/123456789/4680
http://dx.doi.org/10.15488/4638
eng
Advances in Space Research 61 (2018), Nr. 8
0273-1177
https://doi.org/10.1016/j.asr.2018.01.010
https://creativecommons.org/licenses/by/4.0/
CC BY 4.0 Unported
London : Elsevier Ltd.
oai:www.repo.uni-hannover.de:123456789/47102022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-04-01T06:19:35Z
urn:hdl:123456789/4710
Tilt experiment with the autograv relative gravimeter CG-5
Shabanloui, Akbar
Kusche, Jürgen
Scintrex Gravimeter CG-5
Tilt Experiment
Relative Gravimeter
Scintrex Gravimeter CG-5
Neigung Experiment
Relativgravimeter
Scintrex Company Ltd. has built a very precise relative gravimeter AutoGrav CG-5 to explorer mineral, oil and GAS and to detect geotechnical events based on gravity measurements. All of these explorations are based on a glass-quartz spring, which are very sensitive to tilt, shake and temperature changes. Therefore, it is very essential to keep spring in a stable environment and avoiding of tilting and shaking it.
In this investigation, the tilt behavior of glass-quartz spring of the CG-5 Scintrex relative gravimeter is tested. The main goal is to establish a relationship between duration of the tilt and offsets as function of time. Therefore, gravimeter is tilted by placing metal discs of different thickness and different times. The results show that CG5 gravimeter needs some hours to stabilize the glass quartz spring. The behavior of CG5 relative gravimeter and corresponding results will be presented.
2019-04-01T06:19:35Z
2019-04-01T06:19:35Z
2013-10-08
ConferenceObject
Text
Shabanloui, A.; Kusche, J.: Tilt experiment with the autograv relative gravimeter CG-5. Geodätische Woche (2013). https://www.geodaetische-woche.de/
https://www.repo.uni-hannover.de/handle/123456789/4710
http://dx.doi.org/10.15488/4668
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/47152022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-04-01T07:32:10Z
urn:hdl:123456789/4715
Experiment with the Bonn Scintrex CG-5
Shabanloui, Akbar
Kusche, Jürgen
Autograv Relativ Gravimeter,
Scintrex CG-5
Tilt Experiment
Scintrex CG-5
Autograv Relativ Gravimeter
Neigung Experiment
Scintrex Company Ltd has built a very precise and sensitive relative gravimeter AutoGrav CG-5 which is commonly used for mineral, oil and gas geo-technical explorations with an accuracy of 5 Micro-Gal. All of these applications are based on a glass-quartz spring, which are very sensitive to temperature changes, tilt and shake. Therefore, it is very essential to keep spring in a stable environment and avoiding of tilt and shake. In this investigation, the behavior of the CG-5 in Bonn and Bad-Homburg will be discussed. In addition, the tilt behavior of glass-quartz spring of the CG-5 in cooperation with other Institutes is tested. The main goal of tilt experiment is to establish a relationship between duration of the tilt and offsets as function of time. The results show that CG-5 gravimeter needs some hours to stabilize the glass quartz spring.
2019-04-01T07:32:10Z
2019-04-01T07:32:10Z
2013-10-02
ConferenceObject
Text
Shabanloui, A.; Schall, J.; Kusche, J.: Experiment with the Bonn Scintrex CG-5. Journées Luxembourgeoises de Géodynamique, 2.-4. October 2013, Luxembourg
https://www.repo.uni-hannover.de/handle/123456789/4715
http://dx.doi.org/10.15488/4673
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/47142022-11-11T16:14:53Zcom_123456789_1col_123456789_3doc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:520doc-type:Other
2019-04-01T07:24:51Z
urn:hdl:123456789/4714
Global gravity field determination with regional refinements by the analysis of GOCE-level-1b data (GLOREGOCE)
Shabanloui, Akbar
Schall, Judith
Eicker, Annette
Kusche, Jürgen
GLOREGOCE
Global Gravity Field Determination
GOCE Level-1B Data
GLOREGOCE
Globale Schwerefeldbestimmung mit regionalen Verfeinerung
GOCE Level-1B Daten
In this contribution, we present regionally refined gravity field models from GOCE data only using the short arc processing. For easy comparison, regional solutions calculated on small patches all over the globe have been merged and transformed to a spherical harmonic expansion by means of quadrature methods. The power of the regional approach is demonstrated by comparison to the previously calculated ITG-Goce01/ITG-Goce02 spherical harmonic models, which are based on exactly the same processing strategy, standards and data time span. We show, that these global models are comparable in accuracy with respect to the official ESA time-wise models. Second, we verify the gain of regional modelling with respect
to our global models: Compared to EGM08 cut to the oceans, using a land/ocean adjustment of regularisation reduces the global noise by 11%. A more tailored choice of the regularisation areas tested for the South Sandwich Trench reveals the significant improvement of 18%.
2019-04-01T07:24:51Z
2019-04-01T07:24:51Z
2012-05-24
Other
Text
Shabanloui, A.; Schall, J.; Eicker, A.; Kusche, J.: Global gravity field determination with regional refinements by the analysis of GOCE-level-1b data (GLOREGOCE). Poster (2012)
https://www.repo.uni-hannover.de/handle/123456789/4714
http://dx.doi.org/10.15488/4672
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/47112022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-04-01T06:30:26Z
urn:hdl:123456789/4711
REeal data AnaLysis GOCE Gravity field determination from GOCE
Krasbutter, Ina
Baur, Oliver
Brockmann, Jan-Martin
Cai, Jianqing
Eicker, Annette
Kargoll, Boris
Kusche, Jürgen
Mayer-Gürr, Torsten
Schall, Judith
Schuh, Wolf-Dieter
Shabanloui, Akbar
Sneeuw, Nico
GOCE
REALGOCE
Gravity field determination with GOCE
GOCE
REALGOCE
Schwerefeldbestimmung mit GOCE
The Earth's gravity field is determined within the BMBF project REeal data AnaLysis GOCE (REALGOCE).
2019-04-01T06:30:26Z
2019-04-01T06:30:26Z
2012-05-24
ConferenceObject
Text
Krasbutter, I. et al.: REeal data AnaLysis GOCE Gravity field determination from GOCE. BMBF Geotechnologien Statusseminar: "Erfassung des Systems Erde aus dem Weltraum III", 24.05.2012, Potsdam
https://www.repo.uni-hannover.de/handle/123456789/4711
http://dx.doi.org/10.15488/4669
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/49982022-12-02T18:18:52Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:BookPartdoc-type:Textopen_accessddc:520
2019-06-11T12:55:15Z
urn:hdl:123456789/4998
Global Gravity Field Models from Different GOCE Orbit Products
Shabanloui, Akbar
Schall, Judith
Eicker, Annette
Kusche, Jürgen
Global Gravity Field Model
GOCE L1B Data
Precise Satellite Orbit Determination
Globale Schwerefeldbestimmung
GOCE
Satellitenbahnbestimmung
In this contribution, the in-house (processed) GOCE products including precise orbit and Earth’s gravity field are compared to the official ESA products. The comparison is drawn on orbit product as well as gravity field level. To ensure
comparability, gravity field models from both orbits are estimated in an identical
fashion,whichisparticularlytrueforthestochasticalmodel.Wefindthatthein-house processed orbit is piecewise rather smooth, but contains jumps like discontinuities in the calculated geometrical point-wise positions. This leads to a degradation of the gravity field solution about by a factor of two in terms of degree variances when
compared to the solution from the official orbit product. The final version is available at https://link.springer.com/chapter/10.1007%2F978-3-642-32135-1_13.
2019-06-11T12:55:15Z
2019-06-11T12:55:15Z
2014
BookPart
Text
Shabanloui, A.; Schall J.; Eicker, A.; Kusche, J.: Global Gravity Field Models from Different GOCE Orbit Products. In: Flechtner, F.; Sneeuw, N.; Schuh W.D. (Eds): Observation of the System Earth from Space - CHAMP, GRACE, GOCE and future missions. - Berlin : Springer, 2014, S. 103-108. DOI: https://doi.org/10.1007/978-3-642-32135-1_13
https://www.repo.uni-hannover.de/handle/123456789/4998
http://dx.doi.org/10.15488/4954
eng
Observation of the System Earth from Space - CHAMP, GRACE, GOCE and future missions
978-3-642-32134-4
10.1007/978-3-642-32135-1_13
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Berlin : Springer
oai:www.repo.uni-hannover.de:123456789/49992022-12-02T18:18:52Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:BookPartdoc-type:Textopen_accessddc:520
2019-06-11T13:05:08Z
urn:hdl:123456789/4999
Comparison of Daily GRACE Solutions to GPS Station Height Movements
Eicker, Annette
Kurtenbach, Enrico
Kusche, Jürgen
Shabanloui, Akbar
GPS Station Height Movements
Daily GRACE Solutions
GPS Station Höhenänderung
Tägliche GRACE-Lösungen
In Kurtenbach (2011) and Kurtenbach et al. (2012) an approach has been
introduced that allows to calculate daily gravity field solutions from GRACE data
within the framework of a Kalman filter and smoother estimation. The method uti-
lizes spatial and temporal correlations of the expected gravity field signal derived
from geophysical models in addition to the daily observations, thus effectively con-
straining the spatial and temporal evolution of the GRACE solution. Here, we offer
an extended validation of these daily solutions by comparing the derived mass variations to vertical displacements at various permanent GPS stations. The comparison confirms the conclusion that the daily solutions contain significant high-frequent temporal gravity field information, especially in higher latitudes. The final version is available at https://link.springer.com/chapter/10.1007%2F978-3-642-32135-1_6.
2019-06-11T13:05:08Z
2019-06-11T13:05:08Z
2014
BookPart
Text
Eicker, A.; Kurtenbach, E.; Kusche, J.; Shabanloui, A.: Global Gravity Field Models from Different GOCE Orbit Products. In: Flechtner, F.; Sneeuw, N.; Schuh W.D. (Eds): Observation of the System Earth from Space - CHAMP, GRACE, GOCE and future missions. - Berlin : Springer, 2014, S. 47-52. DOI: https://doi.org/10.1007/978-3-642-32135-1_6
https://www.repo.uni-hannover.de/handle/123456789/4999
http://dx.doi.org/10.15488/4955
eng
Observation of the System Earth from Space - CHAMP, GRACE, GOCE and future missions
978-3-642-32134-4
10.1007/978-3-642-32135-1_6
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Berlin : Springer
oai:www.repo.uni-hannover.de:123456789/47132022-11-11T16:15:12Zcom_123456789_1col_123456789_3doc-type:Textopen_accessstatus-type:publishedVersionddc:620ddc:520doc-type:Other
2019-04-01T07:14:42Z
urn:hdl:123456789/4713
Reprocessing of CHAMP and GRACE observations for the determination of improved static and temporal gravity field models with regional refinements
Eicker, Annette
Kurtenbach, Enrico
Mayer-Gürr, Torsten
Shabanloui, Akbar
Kusche, Jürgen
Earth Gravity Field Determination
Reprocessing
GRACE
Schwerefeldbestimmung
CHAMP und GRACE
Reprozessierung
regionale Verfeinerung
Reprocessing of CHAMP and GRACE observations for the determination of improved static and temporal gravity field models with regional refinements
2019-04-01T07:14:42Z
2019-04-01T07:14:42Z
2012-05-24
Other
Text
Eicker, A. et al.: Reprocessing of CHAMP and GRACE observations for the determination of improved static and temporal gravity field models with regional refinements. Poster (2012)
https://www.repo.uni-hannover.de/handle/123456789/4713
http://dx.doi.org/10.15488/4671
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/47122022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-04-01T06:39:21Z
urn:hdl:123456789/4712
GRACE gravity field reprocessing at IGG Bonn
Eicker, Annette
Kurtenbach, Enrico
Mayer-Gürr, Torsten
Shabanloui, Akbar
Kusche, Jürgen
GRACE
gravity field
reprocessing
Schwerefeldbestimmung
GRACE
Reprozessierung
GRACE gravity field reprocessing at IGG Bonn
2019-04-01T06:39:21Z
2019-04-01T06:39:21Z
2012-05-24
ConferenceObject
Text
Eicker, A. et al.: GRACE gravity field reprocessing at IGG Bonn. University of Bonn - Abschlussseminar "Weltraum Phase III", 24.05.2012, Potsdam
https://www.repo.uni-hannover.de/handle/123456789/4712
http://dx.doi.org/10.15488/4670
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/47172022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-04-02T06:30:03Z
urn:hdl:123456789/4717
Precise Orbit Determination of GOCE based on GNSS observations
Shabanloui, Akbar
Kusche, Jürgen
Geometrical Precise Orbit Determination
GOCE
GNSS observations
Geometrische Bahnbestimmung
GOCE
GNSS Beobachtungen
The geometrical point-wise satellite positions can be derived by GNSS (Global Navigation Satellite System) analysis techniques. Based on only geometrical high-
low Satellite to Satellite Tracking (hl-SST) between GNSS satellites and LEO (Low Earth Orbiter), the absolute positions are estimated and defined as geometrical
POD (GPOD). In this paper, the zero differenced estimation procedure will be applied to GOCE (Gravity field and steady-state Ocean Circulation Explorer) observations and results will be discussed. Initial POD results show that the GOCE geometrical point-wise positions can be estimated based on high-low SST with an accuracy of 2-3 cm.
2019-04-02T06:30:03Z
2019-04-02T06:30:03Z
2011-03-29
ConferenceObject
Text
Shabanloui, A.; Kusche, J.: Precise Orbit Determination of GOCE based on GNSS observations. 4th International GOCE User Workshop, 31 March -1 April 2011, Munich (Germany)
https://www.repo.uni-hannover.de/handle/123456789/4717
http://dx.doi.org/10.15488/4675
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/47182022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-04-02T06:48:49Z
urn:hdl:123456789/4718
Global Gravity Field Models from different GOCE Orbit Products
Schall, Judith
Shabanloui, Akbar
Kusche, Jürgen
Global Gravity Field Models
GOCE Orbit Products
Globale Schwerefeldbestimmung
GOCE Satellitenbahn
With GOCE, for the first time in history, a Gravity Gradiometer has been used in space to recover the Earth’s gravity field. Based on the gravity gradiometer observations, the short wavelength part of the Earth gravity field can be determined accurately. The lower frequency part (i.e. the long wavelength) of the Earth gravity field can be extracted from high-low Satellite to Satellite Tracking (hl-SST) data which are observed by the GNSS receiver onboard GOCE. Based on the high-low SST observations, kinematical precise orbit of GOCE can be determined. The kinematical precise orbit of GOCE, which either is estimated with an in-house developed software or supplied as the precise science orbit (PSO) by the European Space Agency (ESA), are used to estimate the Earth gravity field. The physical model of the applied gravity field recovery technique is based on Newton’s equation of motion, formulated as a boundary value problem in the form of a Fredholm's type integral equation. In this paper, the precise orbit product of the GOCE will be validated and the amount of gravity field information within the different orbit products will be compared in a validation step.
2019-04-02T06:48:49Z
2019-04-02T06:48:49Z
2011-06-28
ConferenceObject
Text
Schall, J.; Shabanloui, A.; Kusche, J.: Global Gravity Field Models from different GOCE Orbit Products. IUGG XXV General Assembly, 27 June - 8 July 2011, Melbourne (Australia). http://www.iugg.org/assemblies/2011melbourne/
https://www.repo.uni-hannover.de/handle/123456789/4718
http://dx.doi.org/10.15488/4676
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/47192022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-04-02T06:55:34Z
urn:hdl:123456789/4719
Estimation of phase center variation and its effect on precise orbit determination
Shabanloui, Akbar
Antenna phase center variation
Satellite precise orbit determination
GNSS Antennen-Phasenzentrum
Satelliten Bahnbestimmung
The interest in a precise orbit determination (POD) of Low Earth Orbiters (LEOs) especially in pure geometrical mode only based on GNSS (Global Navigation Satellite System) observations has been rapidly grown. The geometrical absolute positions of LEO can be estimated based on carrier phase SST (Satellite to Satellite Tracking) observations with an accuracy of cm. However, limiting factor for LEO POD is mainly encountered with the modeling of the carrier phase observations, where a phase center location of the GNSS antenna is a pre-requisite for precise determination of LEO orbit. Based on robot calibration, the absolute phase center (PC) and its variation (PCV) are estimated for a number of GNSS receiver antennas. It should be mentioned that for the GNSS transmitter antennas, the absolute phase centers and their variations are estimated based on GNSS data post-processing. Nowadays, the Earth gravity field recovery missions are equipped with non-geodetic receiver antennas, which the phase centers and their variation before launch are determined based on robot calibration strategy. After mission launch, the empirical antenna phase center and phase center variation should be estimated based on GNSS carrier phase observations to improve accuracy LEO orbit. In this paper, different methods to estimate phase center variation are introduced, applied to the twin GRACE and GOCE observations and improvements on POD will be discussed.
2019-04-02T06:55:34Z
2019-04-02T06:55:34Z
2011-06-28
ConferenceObject
Text
Shabanloui, A.: Estimation of phase center variation and its effect on precise orbit determination. IUGG XXV General Assembly, 27 June - 8 July 2011, Melbourne (Australia). http://www.iugg.org/assemblies/2011melbourne/
https://www.repo.uni-hannover.de/handle/123456789/4719
http://dx.doi.org/10.15488/4677
eng
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
oai:www.repo.uni-hannover.de:123456789/47222022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-10T22:05:03Z
urn:hdl:123456789/4722
Mitigation of ionospheric effects on Swarm GPS observations and kinematic orbits
Ren, Le
Lück, Christina
Kermarrec, Gael
Schön, Steffen
Rietbroek, Roelof
Kusche, Jürgen
Ionospheric scintillations
GPS
kinematic Orbits
SWARM
Matérn family
ionosphärische Szintillationen
GPS
kinematische Orbits
SWARM
Matérn famiy
The Swarm mission launched on November 22, 2013 consists of three identical satellites in near-polar orbits, Swarm A and C flying almost side-by-side at an initial altitude of 460 km, Swarm B flying in a higher orbit of about 530 km. Each satellite is equipped with a high precision 8-channels dual-frequency GPS receiver for precise orbit determination. This also offers excellent opportunities to study the ionosphere and to provide temporal gravity field information derived from the kinematic orbits of the satellites for the gap between the Gravity Recovery and Climate Experiment (GRACE) and its follow-on mission (GRACE-FO). However, observations from on-board GPS receiver are strongly disturbed by ionospheric scintillations,
which degrades the kinematic orbits at the geomagnetic equator and at polar areas and thus the gravity field. Due to the different property of ionospheric scintillations, the GPS carrier phase observations suffer also from different types of disturbances. In this contribution, in order to improve the quality of the kinematic orbits, we propose a new method to filter the high-frequency noise and repair the systematic errors in the phase observations, instead of eliminating
or down-weighting the disturbed observations. The kinematic orbits and derived gravity field can be significantly improved. The systematic errors along the geomagnetic equator bands in the gravity field are also successfully eliminated.
2019-04-02T08:28:57Z
2019-04-10T22:05:03Z
2019-04-10
ConferenceObject
Text
Ren, L. et al.: Mitigation of ionospheric effects on Swarm GPS observations and kinematic orbits. In: Geophysical Research Abstracts 21 (2019), EGU2019-9821
https://www.repo.uni-hannover.de/handle/123456789/4722
http://dx.doi.org/10.15488/4680
eng
Geophysical Research Abstracts 21 (2019)
https://doi.org/10.1007/s10291-018-0733-y
info:eu-repo/grantAgreement/Deutsche Forschungsgemeinschaft (DFG)/LEO Potential Field Missions (CONTIM)/SPP1788 Dynamic Earth/EU
https://creativecommons.org/licenses/by/4.0/
CC BY 4.0 Unported
oai:www.repo.uni-hannover.de:123456789/47232022-12-02T18:18:53Zcom_123456789_1col_123456789_3ddc:550doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-09T22:05:41Z
urn:hdl:123456789/4723
Validation of Phase Center Corrections for new GNSS-Signals obtained with absolute antenna calibration in the field
Breva, Yannick
Kröger, Johannes
Kersten, Tobias
Schön, Steffen
GPS/GNSS antennas
GNSS
Geodesy
GNSS receiver antenna calibration
GPS/GNSS-Antennen
GNSS
Geodäsie
GPS/GNSS-Antennenkalibrierung
For high accuracy GNSS applications it is necessary to take phase center corrections (PCC) into account. At the moment PCC from chamber calibrations for various signals are available, however GPS L5 as well as Galileo PCC from field calibrations are still missing. The Institut für Erdmessung (IfE) provides PCC patterns in operational mode for IGS and EPN since several decades. Our group is working to develop calibrations of receiver antennas for new GNSS-signals. For the estimation of the PCC for the new signals we use a post-processing approach modelling the PCC by spherical harmonics. First results and the concept are presented by our group. The focus in this contribution is to validate and verify the resulting PCC for GPS L5 as well as Galileo. A closed loop simulation shows that the pattern can be reliably estimated by our approach. For the verification of the results with real data a short baseline common clock set up at the Physikalisch-Technische Bundesanstalt (PTB) is used, where the receivers are linked to an external ultra stable frequency input. We use various antenna combinations and calculate observed-minus-computed (OMC) values to study the impact of PCC on receiver-toreceiver-
single differences.With observations from several days, the siderial repetition of GPS L5 PCC is analysed.
2019-04-02T08:33:32Z
2019-04-09T22:05:41Z
2019-04-09
ConferenceObject
Text
Breva, Y.; Kröger, J.; Kersten, T.; Schön, S.: Validation of Phase Center Corrections for new GNSS-Signals obtained with absolute antenna calibration in the field. In: Geophysical Research Abstracts 21 (2019), EGU2019-14143
https://www.repo.uni-hannover.de/handle/123456789/4723
http://dx.doi.org/10.15488/4681
eng
Geophysical Research Abstracts 21 (2019)
https://creativecommons.org/licenses/by/4.0/
CC BY 4.0 Unported
oai:www.repo.uni-hannover.de:123456789/47242022-12-02T18:18:52Zcom_123456789_1col_123456789_3ddc:550doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
urn:hdl:123456789/4724
Phase Center Corrections for new GNSS-Signals
Kröger, Johannes
Breva, Yannick
Kersten, Tobias
Schön, Steffen
GPS/GNSS antennas
GNSS
Geodesy
GNSS receiver antenna calibration
GPS/GNSS-Antennen
GNSS
Geodäsie
GPS/GNSS-Antennenkalibrierung
Phase center corrections (including corrections for phase center offset and phase center variations) are nowadays mandatory for high accuracy GNSS applications. Currently, only L1- and L2 frequencies for GPS and GLONASS are provided and published in the Antenna Exchange Format (ANTEX) maintained by the antenna working group of the International GNSS Service IGS. Field calibrations values for new signals like Galileo or GPS L5 are still missing. The Institut für Erdmessung (IfE) is one of the IGS accepted absolute antenna field calibration institutions and provides PCC using the so-called Hannover-Concept, i.e. using a robot to precisely rotate and tilt the antenna under test. This concept has been extended into an experimental approach where PCC of new signals are estimated in post-processing using spherical harmonics. In this contribution, we describe the extended concept and show first patterns for the GPS L5 as well as the Galileo E1 and E5 signals. After a short introduction into the method of absolute antenna field calibration, the roboter model as well as the adjustment concept will be presented.We will show that an estimation of PCC is feasible with the method developed at the IfE. The patterns will be presented and discussed for antennas typical to IGS stations.
2019-04-02T09:16:53Z
2019-04-09
ConferenceObject
Text
Kröger, J.; Breva, Y.; Kersten, T.; Schön, S.: Phase Center Corrections for new GNSS-Signals. In: Geophysical Research Abstracts 21 (2019), EGU2019-14173
https://www.repo.uni-hannover.de/handle/123456789/4724
http://dx.doi.org/10.15488/4682
eng
Geophysical Research Abstracts 21 (2019)
https://doi.org/10.25835/0075279
https://creativecommons.org/licenses/by/4.0/
CC BY 4.0 Unported
oai:www.repo.uni-hannover.de:123456789/47282022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-04T05:51:48Z
urn:hdl:123456789/4728
How important is the dynamical information in determination of LEO orbits
Shabanloui, Akbar
Kusche, Jürgen
Ilk, Karl Heinz
Importance of dynamical information in precise orbit determination
Low Earth Orbiters (LEO)
The interest in a precise orbit determination of Low Earth Orbiters (LEOs) using GNSS observations to recover of the Earth's gravity field has been grown rapidly. With the advent of precise orbit and clock products at centimeter level accuracy provided by the IGS analysis centers and the geometrical connections between GNSS satellites and LEOs, the orbit of LEOs can be estimated based on only a single GNSS receiver onboard LEOs. The determined LEO orbit is based on only geometrical configuration between GNSS and LEO. This procedure is known as Geometrical Precise Orbit Determination (GPOD). The ephemerides of point-wise LEO positions can be derived by this method at every observation epochs. Kinematical Precise Orbit Determination (KPOD) is another estimation procedure, which is based on the geometrical information too. Based on a new proposed method, the kinematical orbit is represented by a sufficient number of approximation parameters, including boundary values of the LEO arc. This kind of orbit representation not only allows to determine arbitrary functional (e.g. velocity and acceleration) of the satellite arc's, but it is also possible to use dynamical observations for the determination of orbit parameters. It should be mentioned that in the geometrical and kinematical orbit determination procedures, no dynamical (force) information is used at all. Because of the close relation of the estimated kinematical parameters with the force function model, the orbit determination can be designed as a pure kinematical orbit determination on the one hand, and a pure dynamical orbit determination on the other hand. In other words, this formulation of the orbit determination allows a smooth transition from a kinematical to dynamical orbit determination. At the one end, the orbit parameters are determined without any force (dynamical) information at all, and the other extreme end, all orbit representing parameters are functions of the force model. If only weak dynamical restrictions are introduced to the estimation procedure, then a reduced-kinematical orbit results. In this poster, the new proposed orbit determination concept will be introduced and the effect of the dynamical information in the orbit determination procedures will be presented for the GOCE mission as a case study based on the simulated data. The various possibilities with the corresponding results of GOCE based on GNSS observations will be presented.
2019-04-04T05:51:48Z
2019-04-04T05:51:48Z
2010-06-28
ConferenceObject
Text
Shabanloui, A.; Kusche, J.; Ilk, K.H.: How important is the dynamical information in determination of LEO orbits. ESA Living Planet Symposium 2010, 28th June 2010, Bergen, Norway
https://www.repo.uni-hannover.de/handle/123456789/4728
http://dx.doi.org/10.15488/4686
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/47292022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-04T05:57:10Z
urn:hdl:123456789/4729
Geometrical and Kinematical Precise Orbit Determination of GOCE
Shabanloui, Akbar
Geometrical and Kinematical Precise Orbit Determination
GOCE
GNSS observations
geometrische und kinematische Bahnbestimmung
GOCE
GNSS Beobachtungen
The geometrical point-wise Low Earth Orbiters (LEO) positions can be derived by Global Navigation Satellite System (GNSS) analysis techniques. The different precise point positioning techniques based on GNSS observations will be designated as Geometrical Precise Orbit Determination (GPOD) methods. In the geometrical determined LEO orbit, there is no connection between subsequent absolute positions, and consequently, no information about the velocity or even the acceleration (or in general kinematical information) of the satellite is available. To describe the time dependency of the motion of a satellite, it is necessary to provide a properly constructed function which consistently connects positions, velocities and accelerations. In this investigation, a new approach is presented based on approximation parameters, which have also a clearly defined relation to the dynamical model of the satellite's motion. If the kinematical parameters are determined by a best fitting process based on the GNSS observations, then we perform a pure Kinematical Precise Orbit Determination (KPOD). The geometrical and kinematical precise orbit of Gravity field and steady-state Ocean Circulation Explorer (GOCE) based on real high-low Satellite to Satellite Tracking (hl-SST) GNSS observations will be presented.
2019-04-04T05:57:10Z
2019-04-04T05:57:10Z
2010-10-07
ConferenceObject
Text
Shabanloui, A.: Geometrical and Kinematical Precise Orbit Determination of GOCE. Geodätische Woche 2010, 5.-7. Oktober 2010, Köln. https://www.geodaetische-woche.de/
https://www.repo.uni-hannover.de/handle/123456789/4729
http://dx.doi.org/10.15488/4687
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/47302022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-04T06:02:00Z
urn:hdl:123456789/4730
An Overview on GNSS Radio Occultation
Shabanloui, Akbar
GNSS Radio Occultation
GNSS-RO
Atmospheric Parameters Estimation
GNSS Radio Okkultation
GNSS-RO
Atmosphärische Parameter Schätzung
An overview on GNSS Radio Occultation (GNSS-RO) technique and its application in geodesy and atmospheric research was presented at the Institute of Astronomical and Physical Geodesy (APMG), University of Bonn in Germany, on 13th July 2010.
2019-04-04T06:02:00Z
2019-04-04T06:02:00Z
2010-07-13
ConferenceObject
Text
Shabanloui, A.: An Overview on GNSS Radio Occultation. Institute of Astronomical and Physical Geodesy (APMG), 13th July 2010, University of Bonn, Germany
https://www.repo.uni-hannover.de/handle/123456789/4730
http://dx.doi.org/10.15488/4688
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/47312022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-04T06:08:34Z
urn:hdl:123456789/4731
Pure Geometrical Precise Orbit Determination of a LEO Based on GNSS Carrier Phase Observations
Shabanloui, Akbar
Ilk, Karl Heinz
Pure Geometrical Precise Orbit Determination (GPOD)
Low Earth Orbiter (LEO)
GNSS Carrier Phase Observations
pur geometrische Bahnbestimmung
niedrigfliegende Satelliten
GNSS Carrier Phase Beobachtungen
The interest in a precise orbit determination of Low Earth Orbiters (LEOs) especially in pure geometrical mode using GNSS observations has been grown rapidly. Conventional GNSS-based strategies rely on the GNSS observations from a terrestrial network of ground receivers (IGS network) as well as the GNSS receiver on-board LEO in double difference (DD) or in triple difference (TD) data processing modes. With the advent of precise orbit and clock products at centimeter level accuracy provided by the IGS centers, the two errors associated with broadcast orbits and clocks can be significantly reduced. Therefore, higher positioning accuracy can be expected even when only a single GNSS receiver is used as zero difference (ZD) procedure. In this paper, the zero difference procedure has been applied to CHAMP high-low SST observations then the solution denoted as Geometrical Precise Orbit Determination (GPOD). The determination of absolute positions based on only carrier phase observations has the disadvantage that the ambiguity term must be determined in addition, but the advantage with respect to the positioning accuracy is significant. The estimated geometrical orbit of CHAMP is point-wise and its accuracy relies on the geometrical status of the GNSS satellites and on the number of tracked GNSS satellites as well as on the GNSS measurement accuracy in the data processing. The position accuracy of 2-3 cm of CHAMP based on high-low GPS carrier phase observations with zero difference procedure has been realized. These point-wise absolute positions can be used to estimate kinematical orbit of the LEOs.
2019-04-04T06:08:34Z
2019-04-04T06:08:34Z
2009-08-31
ConferenceObject
Text
Shabanloui, A.; Ilk, K.H.: Pure Geometrical Precise Orbit Determination of a LEO Based on GNSS Carrier Phase Observations. IAG Symposium, 31st August – 4th September 2009, Buenos Aires, Argentinia
https://www.repo.uni-hannover.de/handle/123456789/4731
http://dx.doi.org/10.15488/4689
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/47322022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:620ddc:520
2019-04-04T06:22:33Z
urn:hdl:123456789/4732
A New Approach for Pure Kinematical and Reduced Kinematical Determination of a LEO Orbit based on GNSS Observations
Shabanloui, Akbar
GNSS Observations
LEO Orbit
Pure Kinematical Determination
Reduced Kinematical Determination
The geometrical point-wise satellite positions can be derived by GNSS analysis techniques. The different precise point positioning techniques will be designated as geometric orbit determination methods. In the Geometrical determined LEO orbit, there is no connection between subsequent absolute positions, and consequently, no information about the velocity or even the acceleration (or in general kinematical information) of the satellite is available. To describe the time dependency of the motion of a satellite, it is necessary to provide a properly constructed function which consistently connects analytically positions, velocities and accelerations.
In this investigation, a new approach is presented based on approximation parameters, which have also a clearly defined relation to the dynamical model of the satellite's motion. To realize this, the kinematical orbit is not only a continuous approximation of the orbit as it is observed by GNSS observations; it is also a solution of Newton's equation of motion of the satellite. If the kinematical parameters are determined by a best fitting process based on the observations, then we perform a pure kinematical orbit determination. In addition, there is also the possibility to use certain constraints based on the dynamical force function model. In this case, we carry out a reduced kinematical orbit determination of a specific level, depending on the strength of the dynamical restrictions. The various possibilities with the corresponding results of CHAMP based on GNSS observations will be presented.
2019-04-04T06:22:33Z
2019-04-04T06:22:33Z
2009-08-31
ConferenceObject
Text
Shabanloui, A.: A New Approach for Pure Kinematical and Reduced Kinematical Determination of a LEO Orbit based on GNSS Observations. IAG Symposium, 31st August – 4th September 2009, Buenos Aires, Argentinia
https://www.repo.uni-hannover.de/handle/123456789/4732
http://dx.doi.org/10.15488/4690
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/47332022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-04T06:27:44Z
urn:hdl:123456789/4733
From pure kinematical to reduced kinematical LEO orbit determination
Shabanloui, Akbar
Precise Orbit Determination (POD)
Low Earth Orbiter (LEO)
niedrigfliegende Satelliten
The geometrical point-wise satellite positions can be derived by GNSS analysis techniques. The different precise point positioning techniques based on GNSS observations will be designated as geometric orbit determination methods. In the geometrical determined LEO orbit, there is no connection between subsequent absolute positions, and consequently, no information about the velocity or even the acceleration (or in general kinematical information) of the satellite is available. To describe the time dependency of the motion of a satellite, it is necessary to provide a properly constructed function which consistently connects positions, velocities and accelerations. In this investigation, a new approach is presented based on approximation parameters, which have also a clearly defined relation to the dynamical model of the satellite's motion. To realize this, the kinematical orbit is not only a continuous approximation of the orbit as it is observed by GNSS observations; it is also a solution of Newton's equation of motion of the satellite. If the kinematical parameters are determined by a best fitting process based on the observations, then we perform a pure kinematical orbit determination. If constraints based on the dynamical force function model are used then the reduced kinematical orbit of a LEO is realized. In this case, we carry out a reduced kinematical orbit determination of a specific level, depending on the strength of the dynamical restrictions. The various possibilities of the reduced kinematical orbit determination with the corresponding results of CHAMP based on GNSS observations will be presented.
2019-04-04T06:27:44Z
2019-04-04T06:27:44Z
2009-09-23
ConferenceObject
Text
Shabanloui, A.: From pure kinematical to reduced kinematical LEO orbit determination. Geodätische Woche 2009, 22.-24. September 2009, Karlsruhe. https://www.geodaetische-woche.de/
https://www.repo.uni-hannover.de/handle/123456789/4733
http://dx.doi.org/10.15488/4691
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/47342022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-04T06:57:09Z
urn:hdl:123456789/4734
A new approach for an integrated kinematic-dynamic orbit determination of low flying satellites based on GNSS observations
Shabanloui, Akbar
GNSS observations
low flying satellites
GNSS Beobachtungen
niedrigfliegende Satelliten
Very precise kinematic or dynamic orbits based on measurements of the Global Navigation Satellite Systems (GNSS) are required to study sea level change and ice cover variations based on the observations of altimetry satellites, atmospheric sounding by GNSS occultation measurements or the detection of mass transports and the mass distribution in the Earth system by a precise determination of the stationary and time variable gravity field. The continuous and precise observation of the orbits of low flying satellites such as CHAMP and GRACE by the GNSS enabled the development of new gravity field determination techniques. The classical approach of satellite geodesy was based on the analysis of accumulated orbit perturbations of artificial satellites with different altitudes and orbit inclinations. This so-called differential orbit improvement technique required the analysis of rather long arcs of days to weeks; it was the adequate technique for satellite arcs poorly covered with observations, mainly precise laser ranging to satellites. Now a very dense coverage with observations of the low flying satellites is available independent from Earth based observation stations and there is no need to use very long arcs with its intrinsic problems. The new alternative gravity field recovery concepts developed in the last couple of years require precise kinematical or reduced dynamical orbits derived from the code and phase measurements. In this paper a new approach for an integrated kinematic-dynamic orbit determination of low flying satellites based on GNSS observations is presented. The short arcs of the low flying satellites are represented by a linear approximation function where the model parameters are also functions of the force function acting on the satellites. This allows the determination of orbits with different kinematic and dynamic orbit characteristics.
2019-04-04T06:57:09Z
2019-04-04T06:57:09Z
2007-09-26
ConferenceObject
Text
Shabanloui, A.: A new approach for an integrated kinematic-dynamic orbit determination of low flying satellites based on GNSS observations. Geodätische Woche 2007, 25.-27. September 2007, Leipzig. https://www.geodaetische-woche.de/
https://www.repo.uni-hannover.de/handle/123456789/4734
http://dx.doi.org/10.15488/4692
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/47352022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-04T07:02:20Z
urn:hdl:123456789/4735
Kinematical LEO Orbit Determination with sequential time differenced GPS SST carrier phase observations
Shabanloui, Akbar
Kinematical LEO Orbit Determination
GPS Satellite-to-Satellite-Tracking (SST) carrier phase observations
Kinematische LEO Bahnbestimmung
GPS SST carrier phase Beobachtungen
SST (Satellite to Satellite Tracking) observations between GPS and LEO (Low Earth Orbiter) play an important role for the determination of precise orbits of LEO satel- lites. These precise orbits are indispensable within the in-situ gravity field recovery procedure based on the in-situ analysis of the satellite’s dynamics. In this article a special technique to determine precise semi-analytical continuous orbits of short arcs of LEO is proposed. The method is based on the solution of Newton’s equation of motion solved as a boundary value problem, constituting the physical model, and zero difference LEO GPS SST carrier phase observations as measured quantities. The procedure allows to determine the orbits in the dynamical and the kinematical mode and everything in-between, considered as so-called reduced dynamic mode of varying level, depending on how much dynamic information is introduced into the orbit determination procedure. In this work, only the kinematical orbit determination mode is investigated. The satellite arcs are represented in the spectral domain. Special polynomials (i.e. Euler-Bernoulli polynomial) have to be used to avoid Gibbs’ effects at the boundaries of the arcs. The precisely kinematically determined short arcs can be used for regional as well as for global gravity field recovery based on the POD (Precise Orbit Determination) in-situ technique.
2019-04-04T07:02:20Z
2019-04-04T07:02:20Z
2007-04-16
ConferenceObject
Text
Shabanloui, A.: Kinematical LEO Orbit Determination with sequential time differenced GPS SST carrier phase observations. EGU General Assembly 2007, 15th-20th April 2007, Vienna, Austria. https://meetings.copernicus.org/egu2007/
https://www.repo.uni-hannover.de/handle/123456789/4735
http://dx.doi.org/10.15488/4693
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/47362022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-04T07:07:00Z
urn:hdl:123456789/4736
Geometrical LEO Precise Orbit Determination (POD) with only sequential time differenced GPS SST carrier phase observations
Shabanloui, Akbar
Ilk, Karl Heinz
Geometrical LEO Precise Orbit Determination (POD)
sequential time differenced GPS SST carrier phase observations
geometrische Bahnbestimmung
differenzierte GPS Satellite-to-Satellite-Tracking Beobachtungen
High-low GPS LEO (Low Earth Orbiter) SST (Satellite to Satellite Tracking) observations play an important role to determine geometrical, precise, 3D orbits of LEO satellites. The ambiguity parameters in the Zero difference technique aren’t integer any more, and the carrier phase observations have to be solved in the float mode. If the difference between two sequential epochs has been built, and the observation rate is small then on the one hand, the ambiguity parameters have been canceled out (if there aren’t any cycle slips in the carrier phase observations), on the other hand many errors in the ZD observations can be eliminated (e.g. antenna phase centre offsets and its variations, multi-path, etc.). Therefore, the sequential time differenced carrier phase observation has been proven to be very efficient for the LEO precise orbit determination. In this paper, as a first step to determine geometrical LEO precise orbits, initial LEO absolute positions have been estimated based on the Bancroft method with an accuracy of a few meters. These absolute positions can be used subsequently as initial values for LEO positions based on pseudo-range ionosphere free observations. To avoid cycle slips in the carrier phase observations, at first, 15 elevation cut-off angle has been applied to the observations, secondly, with the estimated positions in the code pseudo-range process and with the help of the receiver clock offset between two sequential epochs, the cycle slips have been eliminated in the iterative process. It is clear that in this method, the estimated LEO orbit is point-wise (geometrical, not kinematical) and the geometrical configuration (DOP) of GPS satellites plays an important roll in the data processing.
2019-04-04T07:07:00Z
2019-04-04T07:07:00Z
2007-04-16
ConferenceObject
Text
Shabanloui, A.; Ilk, K.H.: Geometrical LEO Precise Orbit Determination (POD) with only sequential time differenced GPS SST carrier phase observations. EGU General Assembly 2007, 15th-20th April 2007, Vienna, Austria. https://meetings.copernicus.org/egu2007/
https://www.repo.uni-hannover.de/handle/123456789/4736
http://dx.doi.org/10.15488/4694
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/47372022-12-02T18:18:53Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-04T07:11:28Z
urn:hdl:123456789/4737
Zero difference geometrical precise orbit determination of low flying satellites with GPS-SST observations
Shabanloui, Akbar
Ilk, Karl Heinz
Zero difference geometrical precise orbit determination of low flying satellites
GPS-SST observations
geometrische niedrig-fliegende Satelliten
GPS Satellite-to-Satellite-Tracking
SST (Satellite to Satellite Tracking) observations between GPS and LEO (Low Earth Orbiter) play an important role to determine precise 3D orbits of LEO satellites. The Zero difference technique has been proven to be very efficient for this task. Zero difference means that the observations between the GPS satellites and the LEO satellite must be used without any differencing (in time or in position). In this work, as a first step to determine precise LEO orbits, initial LEO positions have been estimated based on the Bancroft method with an accuracy of a few meters. These positions can be used subsequently as initial values for LEO positions based on pseudo-range ionosphere free observations. Then the position differences between two sequential epochs can be estimated with an accuracy of approximately 1 cm based on ionosphere free carrier phase observations. The absolutely estimated positions and position differences can be used afterwards to estimate the final absolute positions of a LEO satellite at every epoch, if a sufficient number of GPS satellites i.e. equal or more than four are available.
2019-04-04T07:11:28Z
2019-04-04T07:11:28Z
2006-10-11
ConferenceObject
Text
Shabanloui, A.; Ilk, K.H.: Zero difference geometrical precise orbit determination of low flying satellites with GPS-SST observations. Geodätische Woche 2006, 10.-12. Oktober 2006, München. https://www.geodaetische-woche.de/
https://www.repo.uni-hannover.de/handle/123456789/4737
http://dx.doi.org/10.15488/4695
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/47382022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-04-04T07:15:52Z
urn:hdl:123456789/4738
A proposal for an orbit determination procedure for short arcs of LEO with GPS SST observations
Shabanloui, Akbar
Ilk, Karl Heinz
orbit determination procedure
precise orbit determination
Low Earth Orbiters
GPS SST observations
niedrigfliegende Satelliten
GPS Satellite-to-Satellite-Tracking (SST)
Precise orbit determination of LEO (Low Earth Orbiter) satellites plays an important role in satellite geodesy. In this work, a technique for a precise determination of short arcs (ca. 30 minutes) of low flying satellites is proposed. The procedure is based on the solution of Newton’s equation of motion solved as a boundary value problem. The technique allows determining kinematical orbits without any force function information as well as semi-dynamic with partial force function information or dynamic orbits with full information of the forces acting on the satellites.
Furthermore, the procedure allows a computation in the space domain as well as in the spectral domain. To accelerate the convergence of the solution in the spectral domain, special polynomials (i.e. Euler-Bernoulli polynomial) have to be used to avoid Gibbs’ effects at the boundaries of the arcs. The precisely determined short
arcs can be used for regional as well as for global gravity field recovery tasks.
2019-04-04T07:15:52Z
2019-04-04T07:15:52Z
2005-10-05
ConferenceObject
Text
Shabanloui, A.; Ilk, K.H.: A proposal for an orbit determination procedure for short arcs of LEO with GPS SST observations. Geodätische Woche 2005, 04.-06. Oktober 2006, Düsseldorf. https://www.geodaetische-woche.de/
https://www.repo.uni-hannover.de/handle/123456789/4738
http://dx.doi.org/10.15488/4696
eng
http://creativecommons.org/licenses/by/3.0/de/
CC BY 3.0 DE
oai:www.repo.uni-hannover.de:123456789/48952022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-05-22T05:51:35Z
urn:hdl:123456789/4895
Consistency and impact of mixed receiver antenna phase centre models in regional GNSS networks
Kersten, Tobias
Kröger, Johannes
Breva, Yannick
Schön, Steffen
GPS/GNSS antennas
regional GNSS networks
antenna calibration
carrier phase centre variations
GPS/GNSS Antennen
regionale GNSS Netze
Antennenkalibrierung
Trägerphasenvariationen
The Institut für Erdmessung (IfE) at the Leibniz University Hannover calibrates GNSS antennas determined by the well known robot based concept in the field. Our group has recently improved the calibration procedure to support absolute receiver antenna calibrations for all GNSS frequencies (GPS L1/L2/L5, GLONASS L1/L2 and Galileo E1/E5).
To fully use the advantage of multi GNSS processing capabilities for absolute and relative precise positioning, accurate and consistent receiver antenna calibration patterns of ground stations are required. Currently, in IGS and EPN they are available by chamber calibration method for some antennas. However, systematic and sometimes significant differences exist between both approaches (field robot and chamber) that have to be studied in detail to identify the causes and to fix these issues.
In this contribution, we present first robot based multi GNSS patterns from IfE. Furthermore, a study is performed, to show the impact from the observation domain (differences of antenna phase centre patterns) to the parameter domain (position, troposphere, ambiguities). In this study, we used reference stations from the EPN network which provide individual antenna patterns obtained from both approaches (field robot and chamber). Baselines of lengths ranging from 150-600km and one of 1670km are analysed. We found that on the one hand, differences between both pattern sets do not met the proposed "1mm-rule-of-thumb" in the most of studied cases. On the other hand, we show that in cases of consistent antenna pattern sets no significant differences in the parameter domain are obtained. However, mixing patterns from different approaches implies deviations of up to 1cm (in one case up to 2cm) mostly in the topocentric up component. These differences are directly aligned to the differences in the antenna pattern.
2019-05-22T05:51:35Z
2019-05-22T05:51:35Z
2019
ConferenceObject
Text
Kersten, T.; Kröger, J.; Breva, Y.; Schön, S.: Consistency and impact of mixed receiver antenna phase centre models in regional GNSS networks. Presentation at Euref Symposium 2019, May 22-24, Tallinn, Estonia.
https://www.repo.uni-hannover.de/handle/123456789/4895
http://dx.doi.org/10.15488/4852
eng
https://doi.org/10.25835/0075279
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
CC BY-NC-ND 3.0 DE
Hannover : Institutionelles Repositorium der Leibniz Universität Hannover
oai:www.repo.uni-hannover.de:123456789/50042022-12-02T16:19:29Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:Articledoc-type:Textopen_accessddc:520
2019-06-17T12:04:36Z
urn:hdl:123456789/5004
High tilt susceptibility of the Scintrex CG-5 relative gravimeters
Reudink, R.
Klees, R.
Francis, O.
Kusche, J.
Schlesinger, R.
Shabanloui, Akbar
Sneeuw, N.
Timmen, L.
Scintrex CG-5 autograv
hysteresis
tilt
susceptibility to tilt
accuracy degradation
Scintrex CG5 Gravimeter
Neigung
Genauigkeit Degradierung
We report on the susceptibility of the Scintrex CG-5 relative gravimeters to tilting, that is the tendency of the instrument of providing incorrect readings after being tilted (even by small angles) for a moderate period of time. Tilting of the instrument can occur when in transit between sites usually on the backseat of a car even using the specially designed transport case. Based on a series of experiments with different instruments, we demonstrate that the readings may be offset by tens of µGal. In addition, it may take hours before the first reliable readings can be taken, with the actual time depending on how long the instrument had been tilted. This sensitivity to tilt in combination with the long time required for the instrument to provide reliable readings has not yet been reported in the literature and is not addressed adequately in the Scintrex CG-5 user manual. In particular, the inadequate instrument state cannot easily be detected by checking the readings during the observation or by reviewing the final data before leaving a site, precautions suggested by Scintrex Ltd.In regional surveys with car transportation over periods of tens of minutes to hours,the gravity measurements can be degraded by some 10 µGal. To obtain high-quality results in line with the CG-5 specifications, the gravimeters must remain in upright position to within a few degrees during transits. This requirement may often be unrealistic during field observations,particularly when observing in hilly terrain or when walking with the instrument in a backpack. The final publication is available at https://doi.org/10.1007/s00190-014-0705-0.
2019-06-17T12:04:36Z
2019-06-17T12:04:36Z
2014
Article
Text
Reudink, R. et al.: High tilt susceptibility of the Scintrex CG-5 relative gravimeters. In: Journal of Geodesy 88 (2014), Nr. 6, S. 617-622. DOI: https://doi.org/10.1007/s00190-014-0705-0
https://www.repo.uni-hannover.de/handle/123456789/5004
http://dx.doi.org/10.15488/4960
eng
Journal of Geodesy 88 (2014), Nr. 6
1432-1394
10.1007/s00190-014-0705-0
0949-7714
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Berlin Heidelberg : Springer
oai:www.repo.uni-hannover.de:123456789/50062022-12-02T16:19:29Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2019-06-17T12:33:58Z
urn:hdl:123456789/5006
European Gravity Service for Improved Emergency Management (EGSIEM) - from concept to implementation
Jäggi, Adrian
Weigelt, M.
Flechtner, F.
Güntner, A.
Mayer-Gürr, T.
Martinis, S.
Bruinsma, S.
Flury, J.
Bourgogne, S.
Steffen, H.
Meyer, U.
Jean, Y.
Sušnik, A.
Grahsl, A.
Arnold, D.
Cann-Guthauser, K.
Dach, R.
Li, Z.
Chen, Q.
van Dam, T.
Gruber, C.
Poropat, L.
Gouweleeuw, B.
Kvas, A.
Klinger, B.
Lemoine, J.-M.
Biancale, R.
Zwenzner, H.
Bandikova, T.
Shabanloui, Akbar
Gravity data
mass redistribution
solution combination
near real-time processing
hydrological extremes
EGSIEM prototype services
EGSIEM Prototyp Service
NRT Prozessierung
Hydrologische Extreme
Kombinierte zeitlich-variable Schwerefeld Lösung
GRACE Mission
Earth observation satellites yield a wealth of data for scientific, operational and commercial exploitation. However, the redistribution of mass in the system Earth is not yet part of the standard inventory of Earth Observation (EO) data products to date. It is derived from the Gravity Recovery and Climate Experiment (GRACE) mission and its Follow-On mission (GRACE-FO). Among many other applications, mass redistribution provides fundamental insights into the global water cycle. Changes in continental water storage impact the regional water budget and can, in extreme cases, result in floods and droughts that often claim a high toll on infrastructure, economy and human lives. The initiative for a European Gravity Service for Improved Emergency Management (EGSIEM) established three different prototype services to promote the unique value of mass redistribution products for Earth Observation in general and for early-warning systems in particular. The first prototype service is a scientific combination service to derive improved mass redistribution products from the combined knowledge of the European GRACE analysis centres. Secondly, the timeliness and reliability of such products is a primary concern for any early-warning system and therefore EGSIEM established a prototype for a near real-time service that provides dedicated gravity field information with a maximum latency of five days . Third, EGSIEM established a prototype of a hydrological / early warning service that derives wetness indices as indicators of hydrological extremes and assessed their potential for timely scheduling of high-resolution optical/radar satellites for follow-up observations in case of evolving hydrological extreme events.
2019-06-17T12:33:58Z
2019-06-17T12:33:58Z
2019
Article
Text
Jäggi, A. et al.: European Gravity Service for Improved Emergency Management (EGSIEM) - from concept to implementation. In: Geophysical Journal International 218 (2019), S. 1572-1590. DOI: https://doi.org/10.1093/gji/ggz238
https://www.repo.uni-hannover.de/handle/123456789/5006
http://dx.doi.org/10.15488/4962
eng
Geophysical Journal International 218 (2019)
10.1093/gji/ggz238
https://creativecommons.org/licenses/by/4.0/
CC BY 4.0 Unported
London : The Royal Astronomical Society
oai:www.repo.uni-hannover.de:123456789/50052022-12-02T18:18:52Zcom_123456789_1col_123456789_3status-type:acceptedVersiondoc-type:BookPartdoc-type:Textopen_accessddc:520
2019-11-01T23:05:02Z
urn:hdl:123456789/5005
Calibration of GRACE Accelerometers Using Two Types of Reference Accelerations
Koch, Igor
Shabanloui, Akbar
Flury, Jakob
Accelerometry
GRACE Mission
Satellite accelerometer calibration
Kalibration von Akzelerometer
GRACE Mission
Two approaches for the calibration of GRACE (Gravity Recovery And Climate Experiment) accelerometers are revisited. In the first approach, surface forces acting on the satellite are considered to derive the reference acceleration. In the second approach, the total acceleration consisting of a gravitational and a non-gravitational contribution is first determined from the reduced-dynamic orbits. The approximation of discrete satellite positions by a polynomial function allows the total acceleration to be obtained by a twofold derivative w.r.t. time. Calibration parameters (scale factor and bias) and statistical values are estimated for periods with a low and high solar activity. The quality of these two approaches shows dependencies on solar activity and consequent variations in the magnitude of the non-gravitational reference acceleration. Besides, the quality of the presented results is affected by the orientation of the orbital plane w.r.t. the Sun. The second approach is vitiated by a periodic disturbing signal on cross-track axis. This signal has been pointed out in earlier studies (Calabia et al., Aerosp Sci Technol 45, 2015; Calabia and Jin, Aerosp Sci Technol 49, 2016). We apply a moving window median filter to recover the underlying non-gravitational signal for accelerometer calibration. The calibration is accomplished by a direct comparison of reference accelerations and observed accelerometer measurements without introducing any a priori values or constraints. The focus of this work is more sensor oriented than gravity field recovery (GFR) related. Nevertheless, the results can be used as initial values for precise orbit determination (POD) or for pre-processing of accelerometer measurements in a multi step gravity field recovery approach (Klinger and Mayer-Gürr, Adv Space Res 58(9), 2016). The final paper is available at https://doi.org/10.1007/1345_2018_46.
2019-06-17T12:23:47Z
2019-11-01T23:05:02Z
2018
BookPart
Text
Koch, I.; Shabanloui, A.; Flury, J.: Calibration of GRACE Accelerometers Using Two Types of Reference Accelerations. In: International Symposium on Advancing Geodesy in a Changing World 2017 (IAG Symposia ; 149), S. 97-104. DOI: https://doi.org/10.1007/1345_2018_46
https://www.repo.uni-hannover.de/handle/123456789/5005
http://dx.doi.org/10.15488/4961
eng
International Symposium on Advancing Geodesy in a Changing World (IAG Symposia ; 149) (2017)
IAG Symposia;149
10.1007/1345_2018_46
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Cham : Springer
oai:www.repo.uni-hannover.de:123456789/52372022-12-02T15:02:18Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520ddc:300
2019-08-15T11:13:36Z
urn:hdl:123456789/5237
Mapping similarities in temporal parking occupancy behavior based on city-wide parking meter data
Bock, Fabian
Xia, Karen
Sester, Monika
Timestamp
Data mining
Metre (music)
Occupancy
Similarity measure
Computer science
Data cleansing
Silhouette
Cluster analysis
Hierarchical clustering
The search for a parking space is a severe and stressful problem for drivers in many cities. The provision of maps with parking space occupancy information assists drivers in avoiding the most crowded roads at certain times. Since parking occupancy reveals a repetitive pattern per day and per week, typical parking occupancy patterns can be extracted from historical data. In this paper, we analyze city-wide parking meter data from Hannover, Germany, for a full year. We describe an approach of clustering these parking meters to reduce the complexity of this parking occupancy information and to reveal areas with similar parking behavior. The parking occupancy at every parking meter is derived from a timestamp of ticket payment and the validity period of the parking tickets. The similarity of the parking meters is computed as the mean-squared deviation of the average daily patterns in parking occupancy at the parking meters. Based on this similarity measure, a hierarchical clustering is applied. The number of clusters is determined with the Davies-Bouldin Index and the Silhouette Index. Results show that, after extensive data cleansing, the clustering leads to three clusters representing typical parking occupancy day patterns. Those clusters differ mainly in the hour of the maximum occupancy. In addition, the lo-cations of parking meter clusters, computed only based on temporal similarity, also show clear spatial distinctions from other clusters.
2019-08-15T11:13:36Z
2019-08-15T11:13:36Z
2018
Article
Text
Bock, Fabian; Xia, Karen; Sester, Monika: Mapping similarities in temporal parking occupancy behavior based on city-wide parking meter data. In: Proceedings of the ICA 1 (2018), S. 1-5. DOI: https://doi.org/10.5194/ica-proc-1-12-2018
https://www.repo.uni-hannover.de/handle/123456789/5237
http://dx.doi.org/10.15488/5190
eng
Proceedings of the ICA 1 (2018)
2570-2092
https://doi.org/10.5194/ica-proc-1-12-2018
https://creativecommons.org/licenses/by/4.0/
CC BY 4.0 Unported
Göttingen : Copernicus GmbH
oai:www.repo.uni-hannover.de:123456789/52402022-12-02T15:12:32Zcom_123456789_1col_123456789_7doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2019-08-15T11:13:37Z
urn:hdl:123456789/5240
On the free-precession candidate PSR B1828-11: Evidence for increasing deformation
Ashton, G.
Jones, D.I.
Prix, Reinhard
Pulsar
Physics
Periodic graph (geometry)
Neutron star
Astrophysics
Deformation (mechanics)
Upper and lower bounds
Precession
We observe that the periodic variations in spin-down rate and beam-width of the radio pulsar PSR B1828-11 are getting faster. In the context of a free precession model, this corresponds to a decrease in the precession period $P_{\mathrm{fp}}$. We investigate how a precession model can account for such a decrease in $P_{\mathrm{fp}}$, in terms of an increase over time in the absolute biaxial deformation ($|\epsilon_{\mathrm{p}}|{\sim}10^{-8}$) of this pulsar. We perform a Bayesian model comparison against the 'base' precession model (with constant $\epsilon_{\mathrm{p}}$) developed in Ashton et al (2016), and we obtain decisive odds in favour of a time-varying deformation. We study two types of time-variation: (i) a linear drift with a posterior estimate of $\dot{\epsilon}_{\mathrm{p}}{\sim}10^{-18}\,\mathrm{s}^{-1}$ and odds of $10^{75}$ compared to the base-model, and (ii) $N$ discrete positive jumps in $\epsilon_{\mathrm{p}}$ with very similar odds to the linear $\epsilon_{\mathrm{p}}$-drift model. The physical mechanism explaining this behaviour is unclear, but the observation could provide a crucial probe of the interior physics of neutron stars. We also place an upper bound on the rate at which the precessional motion is damped, and translate this into a bound on a dissipative mutual friction-type coupling between the star's crust and core.
2019-08-15T11:13:37Z
2019-08-15T11:13:37Z
2017
Article
Text
Ashton, G.; Jones, D.I.; Prix, R.: On the free-precession candidate PSR B1828-11: Evidence for increasing deformation. In: Monthly Notices of the Royal Astronomical Society 465 (2017), Nr. 3, S. 164-178. DOI: https://doi.org/10.1093/mnras/stx060
https://www.repo.uni-hannover.de/handle/123456789/5240
http://dx.doi.org/10.15488/5193
eng
Monthly Notices of the Royal Astronomical Society 465 (2017), Nr. 3
0035-8711
https://doi.org/10.1093/mnras/stx060
https://creativecommons.org/licenses/by/4.0/
CC BY 4.0 Unported
Oxford : Oxford University Press (OUP)
oai:www.repo.uni-hannover.de:123456789/52802022-12-02T18:18:52Zcom_123456789_1col_123456789_3ddc:550doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-09-04T22:05:02Z
urn:hdl:123456789/5280
Estimation and validation of receiver antenna codephase variations for multi GNSS signals
Breva, Yannick
Kröger, Johannes
Kersten, Tobias
Schön, Steffen
European Space Agency (ESA)
GNSS
electromagnetics
GPS/GNSS antennas
GNSS receiver antenna calibration
geodesy
GNSS
Elektromagnetik
GPS/GNSS-Antennen
GPS/GNSS-Antennenkalibrierung
Geodäsie
Besides antenna phase center corrections (PCC) for carrier phase measurements, which have to be considered for precise GNSS application, also codephase variations (CPV) exist. These are antenna dependent delays of the code which vary with azimuth and elevation. Such variations are not provided operationally in the antenna exchange format (ANTEX) at the moment. Previous studies in our working group show, that CPV should be taken into account when using code-carrier combination. Depending on the antenna type they can amount up to some dm.
At Institut für Erdmessung (IfE), a concept to determine the CPV has been established. This procedure uses a robot that rotates and tilts the antenna under test precisely in the field. Real world modulated signals from the satellites are used, which is challenging in anechoic chamber procedures. Time differenced single differences are used to estimate PCC and CPV as spherical harmonics (8,8) in a post-processing approach.
In this contribution we present the concept CPV of Galileo signals for several kinds of receiving antennas (mass market and high grade). In addition, we discuss the repeatability and stability of CPV for those antenna. Typical values of the CPV reaches up to 500 mm. The RMS of patterns resulting from multiple calibrations are 80 mm for Galileo C1X and 48 mm for GPS C1C.
2019-08-26T08:55:00Z
2019-09-04T22:05:02Z
2019-09-04
ConferenceObject
Text
Breva, Y. et al.: Estimation and validation of receiver antenna codephase variations for multi GNSS signals. 7th International Colloquium on Scientific and Fundamental Aspects of GNSS, September 4-6, 2019, ETH Zürich, Switzerland
https://www.repo.uni-hannover.de/handle/123456789/5280
http://dx.doi.org/10.15488/5233
eng
7th International Colloquium on Scientific and Fundamental Aspects of GNSS
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
CC BY-NC-ND 3.0 DE
Zürich : European Space Agency (ESA) and ETH Zürich
oai:www.repo.uni-hannover.de:123456789/52832022-12-02T16:19:29Zcom_123456789_1col_123456789_3doc-type:Articledoc-type:Textopen_accessstatus-type:publishedVersionddc:520
2019-08-26T11:54:51Z
urn:hdl:123456789/5283
Multiresolution wavelet analysis applied to GRACE range-rate residuals
Behzadpour, Saniya
Mayer-Gürr, Torsten
Flury, Jakob
Klinger, Beate
Goswami, Sujata
GRACE
gravity
range-rate residuals
orbit determination
For further improvements of gravity field mod- els based on Gravity Recovery and Climate Experiment (GRACE) observations, it is necessary to identify the error sources within the recovery process. Observation residuals obtained during the gravity field recovery contain most of the measurement and modeling errors and thus can be con- sidered a realization of actual errors.
In this work, we investigate the ability of wavelets to help in identifying specific error sources in GRACE range-rate residuals. The multiresolution analysis (MRA) using discrete wavelet transform (DWT) is applied to decompose the resid- ual signal into different scales with corresponding frequency bands. Temporal, spatial, and orbit-related features of each scale are then extracted for further investigations.
The wavelet analysis has proven to be a practical tool to find the main error contributors. Besides the previously known sources such as K-band ranging (KBR) system noise and systematic attitude variations, this method clearly shows effects which the classic spectral analysis is hardly able or unable to represent. These effects include long-term signa- tures due to satellite eclipse crossings and dominant ocean tide errors.
2019-08-26T11:54:51Z
2019-08-26T11:54:51Z
2019-08-15
Article
Text
Behzadpour, Saniya et al. : Multiresolution wavelet analysis applied to GRACE range-rate residuals. In: Geoscientific Instrumentation, Methods and Data Systems 8 (2019), S. 197-207. DOI: https://doi.org/10.5194/gi-8-197-2019
https://www.repo.uni-hannover.de/handle/123456789/5283
http://dx.doi.org/10.15488/5236
eng
Geoscientific Instrumentation, Methods and Data Systems
10.5194/gi-8-197-2019
https://creativecommons.org/licenses/by/4.0/
CC BY 4.0 Unported
Göttingen : Copernicus
oai:www.repo.uni-hannover.de:123456789/52862022-12-02T18:18:52Zcom_123456789_1col_123456789_3ddc:550doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-09-04T22:05:02Z
urn:hdl:123456789/5286
Determination of Phase Center Corrections for Galileo Signals
Kröger, Johannes
Breva, Yannick
Kersten, Tobias
Schön, Steffen
European Space Agency (ESA)
GPS/GNSS antennas
GNSS
geodesy
electromagnetics
GNSS receiver antenna calibration
GPS/GNSS-Antennen
GNSS
Geodäsie
Elektromagnetik
GPS/GNSS-Antennenkalibrierung
GNSS are widely used for positioning, navigation and timing (PVT). The quality of results depends on the antenna in use and the capability to take antenna specific effects into account. The most prominent corrections are the direction dependent phase center corrections (PCC), which include corrections for the phase center offset (PCO) and the phase center variations (PCV). These corrections range between a few up to several millimeters for carrierphase observations and up to some decimeters for code observations. In addition, the magnitude of the error depends on the used antenna type and can differ even for different antennas of the same type and manufacturer.
The frequency-dependent PCC are either determined in an anechoic chamber or in the field using a robot (so-called absolute field calibration). Both methods have their advantages and drawbacks. In the Antenna Exchange Format (ANTEX) from the International GNSS Service (IGS), which is widely used, currently only PCC for L1- and L2 frequencies for GPS and GLONASS are officially published. Absolute field calibrations values for new signals like Galileo or GPS L5 are missing. Only some chamber calibration results are available in the European Permanent Network (EPN).
The Institute für Erdmessung (IfE) is one of the the IGS accepted absolute field calibration institutions and provides PCC using the so-called Hannover-Concept. In this approach a robot is used to precisely rotate and tilt the antenna under test. This concepts has now been extended to an experimental approach. The PCC of new signals are estimated in post-processing as spherical harmonics using time differenced single differences. First results show both – a high repeatability of the estimated pattern and an improvement on the observation domain.
In this contribution the theoretical background as well as the extended concept are described. Moreover, patterns for Galileo signals and GPS L5 will be shown and discussed. After a short introduction into the method and the extended Hannover-Concept the robot model and the adjustment concept will be presented. The contribution will show that the estimation of PCC for Galileo signals is feasible with the developed method. This can be described by the root mean square (RMS) of differential pattern (of different calibrations). This indicator for the repeatability show RMS values for the EL1X signal under 0.6 mm for the NOV703GGG antenna and under 0.4 mm for the LEIAR25.R3. The RMS for the EL5X signal is maximal 0.6 mm for the NOV703GGG or 0.65 mm for the LEIAR25.R3. Furthermore, the obtained patterns will be presented and discussed for several antennas typical to IGS stations. For instance the PCV of the LEIAR25.R3 show values in a range of -4 to 7 mm for the EL1X frequency, whereas the Up-component of the PCO is approximately 60 mm. If these PCC are taken into account, the RMS of the single differences (SD) of a short baseline, common clock experiment at the Physikalisch-Technische Bundesanstalt (PTB) can be improved.
2019-08-27T09:22:09Z
2019-09-04T22:05:02Z
2019-09-04
ConferenceObject
Text
Kröger, J. et al. : Determination of Phase Center corrections for Galileo Signals. 7th International Colloquium on Scientific and Fundamental Aspects of GNSS, September 4-6, 2019, ETH Zürich, Switzerland. DOI: https://doi.org/10.15488/5239
https://www.repo.uni-hannover.de/handle/123456789/5286
http://dx.doi.org/10.15488/5239
eng
7th International Colloquium on Scientific and Fundamental Aspects of GNSS
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
CC BY-NC-ND 3.0 DE
Zürich : European Space Agency (ESA) and ETH Zürich
oai:www.repo.uni-hannover.de:123456789/54142022-12-02T18:18:52Zcom_123456789_1col_123456789_3ddc:550doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-09-17T22:05:03Z
urn:hdl:123456789/5414
Simulation studies to evaluate the impact of receiver clock modelling in flight navigation
Jain, Ankit
Schön, Steffen
navigation
simulation
geodesy
GNSS receiver clock modelling
Navigation
Simulation
Geodäsie
GNSS-Empfängeruhrmodellierung
GNSS based positioning and navigation always require perfect synchronization between the receiver and satellites clock. Further, due to the limited frequency stability of the GNSS receiver’s internal oscillator, an additional receiver clock error has to be estimated along with the coordinates. Thus, the observation geometry is changed; it results in some disadvantages which are: at least four satellites are required for positioning or navigation, high correlations are generated among the estimated receiver clock, the up-component and tropospheric delay, and the up-component is estimated less precisely than the horizontal coordinates. Research has shown that these drawbacks can be avoided by replacing the receiver internal oscillator with a more stable external clock and modelling its operation in a physically meaningful way over intervals in which the oscillator noise is far less than the observation noise. This method is known as receiver clock modelling (RCM). In this contribution, we will present a simulation study which is done to evaluate the gain in performance by RCM in code-based GNSS flight navigation where the height component is of relevance. Different flight test trajectories are simulated with code observation of a multi-GNSS system. Observations for different test trajectories are evaluated with and without RCM using different types of external clocks. The gain in precision of the coordinates for different trajectories w.r.t different clocks will be presented.
2019-09-11T15:04:06Z
2019-09-17T22:05:03Z
2019-09-17
ConferenceObject
Text
Jain, A.; Schön, S.: Simulation studies to evaluate the impact of receiver clock modelling in flight navigation. Poster. Frontiers of Geodetic Science, 17-19 September 2019, Stuttgart, Germany
https://www.repo.uni-hannover.de/handle/123456789/5414
http://dx.doi.org/10.15488/5367
eng
info:eu-repo/grantAgreement/Deutsches Zentrum für Luft- und Raumfahrt e.V./DLR Raumfahrtmanagement/FKZ: 50NA1705/EU
http://creativecommons.org/licenses/by-nc-nd/3.0/de/
CC BY-NC-ND 3.0 DE
Stuttgart : Frontiers of Geodetic Science
oai:www.repo.uni-hannover.de:123456789/54152022-12-02T18:18:52Zcom_123456789_1col_123456789_3ddc:550doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-09-17T22:05:03Z
urn:hdl:123456789/5415
Bestimmung und Validierung von Phasenzentrumskorrektionen für Multi-GNSS-Signale
Kröger, Johannes
Breva, Yannick
Kersten, Tobias
Schön, Steffen
GPS/GNSS antennas
geodesy
GNSS
GNSS receiver antenna calibration
GPS
GPS/GNSS-Antennen
Geodäsie
GNSS
GPS/GNSS-Antennenkalibrierung
GPS
Eine genaue Positionsbestimmung mittels GNSS basiert auf einem präzisen Signalempfang. Im Falle von Trägerphasenmessung stellt ein gleichförmiger Kugelstrahler eine ideale Empfängerantenne dar. Abweichungen von dieser idealen Phasenfront werden als Phasenzentrumskorrektionen (PCC) bezeichnet. In dem vom IGS bereitgestellten Antennenkorrekturen sind zurzeit nur PCC für GPS und GLONASS L1 und L2 vorhanden. Kalibrierwerte für GPS L5 und Galileo-Signale werden bislang nicht vom IGS bereitgestellt. Lediglich im EPN stehen teilweise Kammerkalibrierwerte für diese Signale zur Verfügung. Allerdings haben Untersuchungen unserer Arbeitsgruppe gezeigt, dass bei einer Mischung von Kammer- sowie Roboterkalibrierwerten in großräumigen Netzen signifikante Abweichungen in der Positionsebene auftreten. Daher ist der Bedarf an absoluten Feldkalibrierwerten gegeben. Das Institut für Erdmessung (IfE) ist eine vom IGS anerkannte Kalibrierinstitution und kalibriert operationell nach dem absoluten Verfahren Antennen. In einem neueren Ansatz können nun auch PCC für GPS L5 und Galileo-Signale in einem Postprocessing Ansatz mittels einer sphärisch-harmonischen Funktionen geschätzt werden. In diesem Beitrag wird auf das Robotermodell sowie die Datenerhebung für die Schätzung von PCC eingegangen. Außerdem werden die geschätzten Pattern für verschiedene Antennen vorgestellt sowie validiert. Unsere Untersuchungen haben u.a. ergeben, dass die Wiederholbarkeit der PCC für Galileo-Signale unter 1 mm liegen.
2019-09-11T15:09:13Z
2019-09-17T22:05:03Z
2019-09-17
ConferenceObject
Text
Kröger, J. et al.: Bestimmung und Validierung von Phasenzentrumskorrektionen für Multi-GNSS-Signale. Poster. Frontiers of Geodetic Science, 17-19 September 2019, Stuttgart, Germany
https://www.repo.uni-hannover.de/handle/123456789/5415
http://dx.doi.org/10.15488/5368
ger
http://creativecommons.org/licenses/by-nd/3.0/de/
CC BY-ND 3.0 DE
Stuttgart : Frontiers of Geodetic Science
oai:www.repo.uni-hannover.de:123456789/55302022-12-02T18:18:52Zcom_123456789_1col_123456789_3doc-type:Textdoc-type:ConferenceObjectopen_accessstatus-type:publishedVersionddc:520
2019-09-26T05:19:37Z
urn:hdl:123456789/5530
Konzept und Analyse von Codephasenvatiationen für Multi-GNSS-Signale
Breva, Yannick
Kröger, Johannes
Kersten, Tobias
Schöne, Steffen
GPS/GNSS antennas
Geodesy
GNSS
code phase varaition
GNSS receiver antenna calibration
GPS/GNSS-Antennen
Geodäsie
GNSS
Codephasenvariationen
GPS/GNSS-Antennenkalibrierung
Für hochpräzise GNSS-Anwendungen sind Trägerphasenmessungen unabdingbar. Bei solchen Messungen ist es notwendig die individuellen Antennenphasenzentrumskorrekturen (PCC) zu berücksichtigen. Ähnliche Korrekturen existieren auch für Codebeobachtungen, so genannte Codephasenvariationen (CPV). Diese sind antennenabhängige Verzögerungen der empfangenen Codephase und können bis zu mehreren Dezimetern erreichen. Solche Variationen werden bisher nicht operationell im ANTEX Format bereitgestellt. Das Institut für Erdmessung (IfE) hat ein Konzept entwickelt, mit dem neben PCC für Trägerphasenmessungen auch CPV für alle GNSS geschätzt werden können. Dafür wird ein Roboter genutzt, der es erlaubt, einen Antennenprüfling um einen Punkt zu rotieren und zu kippen. Dabei werden echte GNSS-Signale der sichtbaren Satelliten genutzt. Durch Bildung von zeitdifferenzierten Einfachdifferenzen ist es möglich, PCC und CPV zu schätzen, da diese lediglich das Pattern des Antennenprüflings beinhalten. In einem post-processing Ansatz werden mit sphärisch harmonischen Funktionen (8,8) die gewünschten Parameter geschätzt. In diesem Beitrag präsentieren wir unser Konzept zur Schätzung von CPV für GPS sowie Galileo Codephasen-Signale und die erzielten Ergebnisse. Dabei gehen wir auf die Wiederholbarkeit der Pattern unseres Verfahren ein, indem wir die Daten mehrtägige Kalibrierungen analysieren. Des Weiteren werden wir eine Validierung der geschätzten CPV auf Beobachtungs- und Koordinatenebene präsentieren.
2019-09-26T05:19:37Z
2019-09-26T05:19:37Z
2019-09-19
ConferenceObject
Text
Breva, Y.; Kröger, J.; Kersten, T.; Schön S.: Konzept und Analyse von Codephasenvariationen für Multi-GNSS-Signale. Vortrag. Frontiers of Geodetic Science, 17-19 September 2019, Stuttgart, Germany
https://www.repo.uni-hannover.de/handle/123456789/5530
http://dx.doi.org/10.15488/5483
ger
http://creativecommons.org/licenses/by-nd/3.0/de/
CC BY-ND 3.0 DE
Stuttgart : Frontiers of Geodetic Science
oai:www.repo.uni-hannover.de:123456789/65152022-12-02T07:32:52Zcom_123456789_1com_123456789_2961col_123456789_4col_123456789_2962doc-type:Textopen_accessstatus-type:publishedVersionddc:520doc-type:DoctoralThesis
2019-11-15T07:46:08Z
urn:hdl:123456789/6515
Textursynthese und -analyse für Anwendungen der Kartographie und Luftbildauswertung
Stahlhut, Oliver
Texture
synthesis
segmentation
Markov random fields
MRF
remote sensing
aerial images
[no abstract]
2019-11-15T07:46:08Z
2019-11-15T07:46:08Z
2004
DoctoralThesis
Text
Stahlhut, Oliver: Textursynthese und -analyse für Anwendungen der Kartographie und Luftbildauswertung. Hannover : Universität, Diss., 2004, 117 S.
https://www.repo.uni-hannover.de/handle/123456789/6515
http://dx.doi.org/10.15488/6463
ger
urn:nbn:de:gbv:089-47312128X6
Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
Hannover : Universität
didl///ddc:520/100