Map understanding for GIS data capture: Algorithms for road network graph reconstruction

The authors describe a high level method for reconstruction of a road network graph extracted from scanned maps. The corrupted graph that results from low-level treatments contains all the information needed for a correct reconstruction if one takes into account the a priori knowledge. A list of rules that contains this knowledge, is given. Formally, the problem is to construct the most likely graph considering a priori knowledge and the corrupted graph with which one started. An algorithmic approach is presented. The authors describe the different algorithmic steps used; each step uses a specific subset of the rules considered. As much as possible, to proceed by global optimization inside each step. The results obtained are good enough for use in GISs (geographic information systems) except for cities