ASTER DEMs for geomatic and geoscientific applications: a review

Most geoscientific applications using georeferenced cartographic/geospatial data require good knowledge and visualization of the topography of the Earth's surface. For example, mapping of geomorphological features is hardly feasible from a single image; three‐dimensional (3D) information has to be generated or added for a better interpretation of the two‐dimensional data. Since the early emergence of earth observation satellites, researchers have investigated different methods of extracting 3D information using satellite data. Since the early experiments with the Earth Terrain Camera flown onboard SkyLab in 1973 to 1974, various analogue or digital sensors in the visible or microwave spectrum have been flown to provide researchers and geoscientists with spatial data for extracting and interpreting 3D information of the Earth's surface. Stereo viewing using digital scanner images, such as with the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) along‐track sensors, was, and still is, the most common method used by the mapping, geomatic, and geoscientific communities for generating digital elevation models (DEMs). This paper will review the basic characteristics of stereoscopy and its application to the ASTER system for DEM generation. It will thus address the methods, algorithms and commercial software to extract absolute or relative elevation and assess their performance using the results from various research and commercial organizations. It will finally discuss the use of stereo ASTER DEMs for different geomatic and geoscientific applications.