Dynamic digital distance maps in two dimensions

An efficient means for dealing with obstacles in motion is provided to extend the usefulness of digital distance maps. An algorithm is presented that allows one to compute what portions of a map will probably be affected by an obstacle´s motion. The algorithm is based on an analysis of the distance transform as a problem in wave propagation. The regions that must be checked for possible updates when an obstacle moves are those that are in its or in the shadow of obstacles that are partially in the shadow of the moving obstacle. The technique can handle multiple fixed goals, multiple obstacles moving and interacting in an arbitrary fashion, and it is independent of the technique used for calculation of the distance map. The algorithm is demonstrated on a number of synthetic two-dimensional examples, and example timing results are reported