Use of DTMs/DSMs and Orthoimages to Support Building Extraction

The acquisition of 3D models of buildings and other man-made objects is currently an issue of high importance to many users of geoinformation, including planners, geographers, architects, etc. Aerial imagery has proven to be a valuable data source for these models. The project AMOBE1, a joint research effort between the photogrammetry and image sciences groups at ETH, aims firstly at developing practical algorithms to support the semi-automatic reconstruction of man-made objects from aerial imagery and secondly, at developing improved techniques for automatic digital terrain and surface model generation. In the latter case it is important to differentiate between terrain models (DTMs), which model the terrain, and surface models (DSMs), which model all 3D objects. In this paper, we explore the roles of both DTMs and DSMs and their derived products orthoimages in supporting the extraction of buildings from aerial imagery. In Section 3 the quality of commercially available automatic DTM/DSM generation software is investigated. In Section 4 a number of methods for automatically detecting buildings in DSMs are presented and evaluated. In Section 5, the use of DSMs in deriving coarse building models is described. Applications of orthoimages are discussed in Section 6. First, however, the fundamental assumptions and strategy employed in AMOBE is outlined. Note finally that the techniques and tests described in this paper constitute preliminary investigations. Promising directions, as noted, are the subject of ongoing research.