A Method of Extracting Feature Contour from Triangular Mesh Surface Model of Fractured Solid

The aim of this paper is to find the way to extract feature contour from triangular mesh surface model of fractured solid for shape matching based-on 3D feature curve. Firstly, we give some definitions to distinguish between external surface and fractured surface, internal boundary line and external boundary line, internal contour line and external contour line. Then we present a complete process of extracting feature contour from 3D models. The process includes the following steps: description of attribute for internal and external boundary line, computation of angle of normal vectors, evaluation of angle between external and fractured surface according to the statistics on geometry character from a lot of broken relic fragment and the upper limit of acreage for fractured surface. The core idea of this paper is that the feature contour is the intersection between external surface and fractured surface and its adjacency area changes exquisite in point of geometry character. Through the processing, the precise contour is extracted and the shape matching could be conducted.