Automatic measurement of sewer man-holes in large scale aerial images

Abstract

The geometric changes of the surface (subsidence and horizontal displacement) caused by coal mining can be determined by photogrammetry with a sufficient accuracy. As long time stable targets sewer manholes can be used. They can be identified in large scale aerial images without additional effort for targeting. They also can be measured semi-automatic in digital images. Especially for periodically performed photogrammetric evaluations of the same area these aspects can lead to a significant cost reduction against a manual measurement. The program DPLX developed by the University of Hannover resulted in a precision and completeness of the automatic image point determination similar to those by manual measurement with analytical plotters. Digital images with the full resolution can be handled also on standard PC's. © 2000 International Society for Photogrammetry and Remote Sensing. All rights reserved.