From Grids To Topology
Basis points: the closest points in the occupied space
Clearance: the distance to the basis points
Voronoi diagram: the set of points in free space that have ɭ different (equidistant) basis points
Critical points: points on the Voronoi diagram that minimize clearance locally
Critical lines: connect each critical point with its basis points
Topological graph: each region is mapped into a node, each critical line is mapped into an arc