A boundary identification method for 3D closed triangle mesh

A boundary identification algorithm for the hole of 3D closed triangle mesh is presented in this paper. The region of interest is selected by mouse dragging. Combine with the continuous hole silhouette obtain by the dot product between the triangle normal and the viewing direction we can find the 3D hole boundary of the outer surface. The other hole boundary can be searched according to the curve point set and the hole silhouette. This algorithm can simplify the interactive operation for the identification of the hole boundaries on the model which is a 2-manifold, oriented, closed and non-simple connected triangle mesh and improve the efficient of relative geometric design system.