Detailed Relief Modeling of Building Facades from Video Sequences

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. Altough 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. For very high demands on photorealistic quality, textures mapped on simple geometric models like polyhedra or regular surfaces are not sufficient because relief structure is not preserved. This leads to an unrealistic and artificial impression on close-up views. Relief structures are beneficial for large scale models that are closely inspected within a limited area in a virtual world. In this paper the extraction of reliefs to improve existing planar surfaces of wire frame models of buildings is described. Given several uncalibrated views onto a surface of the polyhedral model, a depth map is estimated by correlation. The underlying plane is used to guide the correlation in order to detect outliers and to fill in homogeneous areas.