BRIDGE HEIGHT ESTIMATION FROM COMBINED HIGH-RESOLUTION OPTICAL AND SAR IMAGERY

Today’s airborne (Memphis, AeS-1, Ramses) and space borne (TerraSAR-X, CosmoSkyMed, Radarsat) SAR sensors provide very high resolution imagery independent of daylight and cloud coverage. Space borne systems achieve geometrical resolutions of down to one meter while airborne sensors are capable of acquiring images with sub metric resolution. In this kind of data, urban objects like buildings and bridges become visible in much detail. However, due to the side-looking SAR sensor principle, layover and occlusion hamper the interpretation particularly in urban scenes. One possibility to overcome this drawback is the use of additional information from high resolution optical imagery. In this paper, first findings of a long term project using both optical and SAR imagery for the modelling and extraction of bridges are presented. The focus is on bridges because they play a key role as connecting parts of man-made infrastructure and are of high importance in case of rapid natural hazard response. Differences between bridges over water and bridges over land are explained. Furthermore, concepts for estimating bridge heights from of a single SAR image and by means of combined optical and SAR imagery are derived. * Corresponding author