In prior games, they would subdivide the map down into a grid-style collection of nodes that would form larger and smaller rectangles. I don''t know if they did that in WC3. I doubt it since the map style is significantly different. Chances are, they are determinining unpassable areas and passable ones and creating a mesh of nodes and paths between them.

Dave Mark - President and Lead Designer
Intrinsic Algorithm - "Reducing the world to mathematical equations!"