Matching of Ikonos Stereo and Multitemporal GEO Images for DSM Generation

Investigations on the use of stereo GEO and multitemporal GEO Ikonos images for DSM generation are reported. Both an own developed matching algorithm and the digital photogrammetric systems LH Systems DPW770 and VirtuoZo were used. In our own matching method, we start with quasi-epipolar image generation, and derivation of approximations using grid point matching based on relaxation. The final matching is a modified multi-image geometrically constrained method. Test results on both methods are presented. Firstly, DSMs were generated from multitemporal GEO images, which theoretically should be more difficult to match, by using our own matching procedure. Different matching versions, with and without exclusion of the different cloud areas, were tried and compared to a reference DTM with an accuracy of ca. 3 m. The results showed a very promising RMS of slightly over 3 m without any manual editing. The second example refers to a DSMs generation from a GEO stereo-pair by matching using LHS DPW770 and VirtuoZo and compared to results from aerial imagery. Due to large multitemporal differences between the two datasets, stable points were manually selected and measured. These points and other points in stable open areas that were automatically matched in the aerial imagery using VirtuoZo served as reference data. The results showed a high relative accuracy of ca. 1 m but the presence of a larger systematic error of 2-3 m.