DEM generation from satellite data

ABSTRACT: Digital Elevation Models (DEMs) are required for several tasks like generation of orthoimages, flood planning, erosion control, agriculture, generation of contour lines, visibility check, 3D-views and oth-ers. Mainly in developed countries DEMs are available, but not in any case like required. DEMs can be gen-erated by traditional photogrammetry based on aerial photos if they are available and not classified, but also very often more economic by means of space images. Another possibility is the use of airborne laser scan-ning – this will lead to very detailed and accurate information, but it is expensive. With Interferometric Syn-thetic Aperture Radar (InSAR) it is also possible to get the height information. The achieved accuracy of DEMs based on space images is mainly depending upon the image resolution, the height-to-base-relation and the image contrast. In addition, systematic image errors of photographic products, but also a limited orientation quality may cause a difference between a relative and an absolute accuracy. Photographic data still do play an important role because of the up to now only a limited number of digital stereo pairs and the very often lower price. Following systems have been analyzed: Metric Camera, Larg