Abstract: Triangular mesh clipping is widely used in grid reconstruction, grid deformation, terrain fusion and analysis, and many other fields. In the application of geographic information system (GIS), triangular mesh clipping is the key to the fusion of terrain surface model and building model. However, existing polygon clipping algorithms do not take the space relationship of adjacent triangles into account.If they were directly used in triangular mesh clipping, T-intersections would appear in the cutting results, leading tounstable triangular mesh. In order to solve this problem, a triangular mesh clipping algorithm based on triangular decomposition is proposed. Triangular decomposition is implemented according to the location relationship between the triangle and the cutting line, whichdoes not introduce other intersections that are not on the polygon line. Results of the experiments show that the decomposition algorithm can avoid T-intersections and effectively generate stable triangular mesh.

Key words: triangular mesh clipping, T-intersections, triangular decomposition, polygon clipping