Automatic recognition of boundary features of non-closed triangulation model

Filling holes is one of the most important studies in reverse engineering,and before hole filling we have to locate and recognize the hole boundary features exactly.The recognistion of non-closed triangular mesh model boundary and the hole boundary may adopt man-machine interaction means.A new method of boundary auto recognition is presented in it,the boundary vertexes and boundary grid are projected onto the projection plane for corresponding projecting feature to obtain a boundary projecting polygon,which will be recognized by utilizing the sum and knowledge of polygon of plane geometry and.If the angle sum of non-mesh corresponded with the polygon boundary projected is equaled to the internal angle sum of the boundary polygon,the boundary is a hole boundary,othervise it is a model boundary.This method is verified through practical examples to be able to recognize automatically and separate the hole boundary and model boundary,which improve the working efficiency of hole boundary recognition in reverse engineering.