Automatic Ortho-rectification of ASTER Images by Matching Digital Elevation Models

The ortho-rectification of satellite images is normally a timeconsuming and expensive task. It can strongly benefit from automatic or semiautomatic procedures in order to avoid field work for ground control survey. This article presents an automated method to automatically georeference satellite images acquired by the ASTER sensor. The method is based on automatic matching of images and Digital Elevation Models (DEM). First a DEM is extracted from the two stereo image bands, which then is matched to the SRTM (Shuttle Radar Topography Mission) DEM in order to correct its position in a map reference system. This allows for the simultaneous correction of image geo-location, which then is followed by the ortho-rectification. The method was applied to an ASTER image from North Portugal and assessed using topographic map data. It was possible to geo-reference images in hilly terrain with positional accuracy better than one pixel.