Digital Elevation Models

Digital elevation models are an important component of any Geo-Information System (GIS). This keynote provides an overview of the satellite stereo model orientation and image matching methods currently used to generate Digital Elevation Models (DEMs). Using very high resolution stereo pairs of satellite images, DEMs with a standard height deviation in the range of 1m or even better can be generated within a limited time. Their generation is expensive, so we should have a look to free of charge available DEMs. With ASTER GDEM3, SRTM, AW3D30 and TDX-EDEM we have four global or nearly global free available. Their advantages and disadvantages are discussed. The edited version of TanDEM-X (TDX-EDEM) is the latest product published end of 2023. As reference for the analysis, LiDAR Digital Terrain Models (DTMs) with the height of the bare ground are used with an accuracy of ~ 20cm. The global or nearly global DEMs are Digital Surface Models (DSMs) with the height of the visible surface. For the comparison with the reference DTM, areas with high vegetation and buildings must be excluded, which was possible with the Land Cover Map (LCM) of TDX-EDEM. TDX-EDEM clearly offers the highest accuracy, but in steep mountains and built-up areas we should also take a look to AW3D30.