Topographic Mapping with High Resolution Optical Space Images

Topographic mapping traditionally was based on aerial images. With high and very high resolution optical space images now a competition to aerial images exists. The optical space images today are available without restrictions. Dominating criteria for mapping are the accuracy and the information content – what elements can be identified in the images. The accuracy is determined by the scene orientation and the relative accuracy within the stereo model. The direct sensor orientation reaches standard deviations up to 2m. If this is not satisfying or sensors with lower direct sensor orientation accuracy shall be used, ground control points or other methods for the scene orientation have to be used. The location accuracy of the SRTM height model or TerraSAR-X scenes for several applications is satisfying and SRTM can be used instead of control points. The relative accuracy within the stereo model is not the limiting factor for the possible map scale, this is the information contents or object identification. The information content is dominated by the ground sampling distance (GSD), but it may be influenced also by the image quality. The image quality can be analyzed by edge analysis.