3d-modeling of Urban Structures

Three dimensional building models have become important during the past years for various applications like urban planning, enhanced navigation or visualization of touristic or historic objects. 3D-models can increase the understanding and explanation of complex urban scenarios and support decision processes. A 3D-model of the urban environment gives the possibility for simulation and rehearsal, to "fly through" the local urban structures with multiple perspective viewing, and to visualize the scene out from different viewpoints. The building models are typically acquired by (semi-) automatic processing of Laser scanner elevation data or aerial imagery. We are presenting an automatic generation method of polyhedral 3D-models from Laser height data in our paper. The methods of deriving a DTM and a DSM from the data as well as the estimation of a ground map for the built-up area as alternative of a cadastral map are especially investigated. An approach for the classification of vegetation areas is presented. Although for some applications geometric data alone is sufficient, for visualization purposes a more realistic representation with textured surfaces is necessary. The associated textures from buildings are extracted either from airborne imagery or, especially for facades, from images taken by ground based cameras. We have investigated the selection of optimal texturing images from the acquired data including occlusions and multiple representations. Results are presented.