Information content of optical satellite images for topographic mapping

Geometric high-resolution satellite imagery (HRSI) is being used increasingly for generating large-scale topographic maps. The detection of object shapes has become easier and more accurate with improved geometric resolution. The grey value range and spectral resolution are also important for the identification and classification of objects. The nominal ground sampling distance (GSD) must not be the same as the effective GSD corresponding to the information content. In addition, the topographic conditions, object contrast, sun elevation and azimuth and atmospheric conditions influence the object identification. The information content of panchromatic and multispectral satellite images (Landsat 7 ETM+, ASTER, TK-350, KVR-1000, SPOT-5, IRS-1C, IKONOS, QuickBird and OrbView-3) available for the Zonguldak test field were investigated with respect to the generation of large-scale topographic maps. The rule of thumb for topographic mapping of at least 0.1mm GSD in the map scale with the limit of a maximum of 5m GSD also for smaller map scales has been confirmed.