A parallel algorithm to skeletonize the distance transform of 3D objects

A 2-subiteration parallel algorithm is suggested to compute the surface skeleton of a 3D digital object represented by its D6 distance transform, without resorting to directional processes. The algorithm is based on the use of two operators, with 3x3x3 and 2x2x2 support, that are, respectively, applied during the two subiterations to mark the voxels of the D6 distance transform to be ascribed to the skeleton. The resulting surface skeleton is centered within the object, is homotopic to the object and is fully reversible since it includes all centers of the maximal balls of the object.