Automatic interpretation of contour lines by using external data

A project on topographic maps interpretation is being driven at I.G.N. (Institut Geographique National, France). The aim of this project is to provide a totally automatic interpretation with a call to operator on the only suspicious cases detected by the program. This paper presents an automatic system for the creation of a Digital Terrain Model (DTM) out of a scanned map. Our proposed method is based on the use of external elevation information and on a combined local/global strategy for quoting the portions of curve present on the map. To reduce the combinatory of the problem, and to accelerate the convergence, all the “trivial cases” of interruption are pretreated. After having quoted the portions of curve, a DTM is created by a classical interpolation method