Urban Environment Modelling by Fusion of a Cadastral Map and a Digital Elevation Model

This paper describes a method to automatically construct a 3D geometric model of an urban area by merging features extracted from a cadastral map of the area and from the corresponding digital elevation model (Dem). The cadastral map and the Dem are both transformed into two sets of contour segments: The segments extracted from the map represent contours of buildings and blocks of buildings, whereas the segments extracted from the Dem represent the external edges of blocks of buildings (edges of buildings are generally missed because buildings of a same block often have the same height). The fusion of these two sets takes two main steps. The Dem segments are rst matched with map segments by pruning a correspondence graph using a maximal clique technique. The result gives the 3D structure of the blocks of buildings. The remaining map segments, i.e. those which have no correspondent in the Dem, represent the contours of the buildings inside the blocks. The elevation of such a segment can then be estimated from the previously matched segments with which it is connected in the 3D structure. Some results and perspectives are presented as a conclusion.