Comparison of estimated building story number for exposure mapping from high resolution space-borne images

In this paper, two different approaches are proposed for the estimation of building footprints and number of stories using high resolution space-borne images. To this aim, semiglobal matching (SGM) is used to generate normalized digital surface models (nDSM) from stereo pairs. Alternatively, a height-from-shadow approach (called “shadow-raiser”) is implemented by detecting building rooftops and related shadow regions. Using associated lengths of shadow, the building heights are computed based on sun elevation and azimuth. The results of the proposed algorithms using IKONOS and GeoEye images demonstrate promising results with SGM, although the building dimensions are usually overestimated. In contrast, shadow-raiser delivers good results only if the building-shadow pair is correctly detected. Moreover, it suffers from an overestimation for building height if shadow areas are mixed up with occluded areas, vegetation or roads.