Extraction of road network using amodified active contour approach

Road network extraction from digitized map consists in partitioning a map into two different classes (road and background) distinguished with their intensity values and geometric shape. In this paper, we propose a semi-automatic method where user intervention is minimal. We adopt a variational framework where a minimization energy is proposed. Roads are tracked by active contours which evolve according to evolution equations derived from the energy minimization. We consider that the energy is composed of three main terms which have never been combined and used in such application. The first term is the geodesic active contour (GAC) which is contour-based and which evolves toward high gradients in the image. The second term matches the intensity distribution inside the contour with a model distribution. The third term is a geometric constraint which describes the thin structure of routes. The user intervention is restricted to learning the road intensity model.