中文摘要：

提出一种综合利用线框模型几何信息和拓扑信息的表面识别算法。首先利用平行投影法将3维线框模型投影到2维平面上，隐藏被遮挡边和悬边悬链；然后在可见投影边线图中，根据各个顶点的关联边序列，按照顺时针最小转角原则搜索最小回路；最后根据Moebius规则和二流形体的性质，及时删除不是表面投影的非法回路和图中的完备边，并调整回路的方向，使其均指向体外。通过各类典型立体的表面识别实验表明，算法具有广泛的立体适应能力和较高的效率。

英文摘要：

This paper presents an efficient algorithm for extracting faces from polyhedral wireframe models. The main features of the algorithm are using the topological and geometric information of wireframe models and its stronger adaptability. First, the wireframe model is projected to a plane, and the ＂invisible＇＇ edges which are obstructed by another edge in projection are hidden. And the edges which have a common vertex are arranged into a set in counterclockwise. Then search the minimal circle based on rule of the smallest rotation angle in clockwise. At the same time the Moebius rule are use to delete the illegal circle and remove the finished edges which are accurately contained by two circles. When a ＂visible＂ edge is removed, ＂invisible＂ edges blocked by it may be ＂ visible＂ ones. So the new minimal circle can be searched. Repeat this course until all edge is removed and there are no illegal circle and illegal edge. Finally,the remaining circle are all true face of the model and all point to outside of the object by adjusting their direction. Several typical examples are given to demonstrate the widespread adaptability and high efficiency of the algorithm.