A line sweep thinning algorithm

We propose a new thinning algorithm based on line sweep procedures. A line sweep is a process where the plane is divided into parallel slabs by lines passing through certain "events" and then items are processed according to an order of the slabs. Assuming that the contours of the object that are to be thinned have been approximated by polygons, the "events" are then the vertices of the polygons and the line sweep algorithm looks for pairs of polygon sides that lie within each slab. Since the procedure is applied in both horizontal and vertical direction, possible conflicts may exist among the pairs of polygon sides. A subsequent effort is to resolve the conflicts according to a few generic types into which they can be classified. After the conflict resolution, the object can be decomposed into the regions that can be represented by the skeletons computed from the pairs of polygon sides, and the regions that are the singular parts of the object. Both types of regions can be used as features for subsequent pattern recognition operations.