I have points locating supermarkets. I would like to use the Voronoi method to automatically delineate the catchment area of each supermarket (in real life of course it overlaps a bit on each other but I don't need this level of detail). I am wondering if it is possible to take into account large physical or man-made obstacles which have a real effect on the catchment areas. For instance, a highway with few under or overpasses, a (large) river, a large drop in elevation... Can the Voronoi method (or any other method) take this into account if the obstacles are represented as open polylines? I guess that another way would be to manually crop the part of the voronoi area that intersect the obstacle but I wonder if there is a way to take this into account in the process itself.