Volume decomposition and feature recognition, part II: curved objects

Abstract

A method has been developed that decomposes a curved object into volumes, called maximal volumes, with the half-spaces of the object. A maximal volume has as few concave edges as possible without introducing additional halfspaces. The object is first decomposed into minimal cells by extending the surfaces of the object. Combinations of these minimal cells are then composed to form maximal volumes. The combinations of such minimal cells that result in maximal volumes are found by traversing a search tree which is pruned by examining the relationships among these minimal cells. One application of this decomposition method is recognition of machining features. With this decomposition method, a delta volume is decomposed into maximal volumes. Many maximal volumes are readily recognizable as features with graph matching. Compound features can be recognized by combining maximal volumes. By subtracting maximal volumes from each other in different orders and applying graph matching to the resulting volumes, multiple interpretations of features can be generated.