关键词: 细分曲面, 求交, 裁剪, 参数化

Abstract: Based on parametrization representation of subdivision surfaces，precise intersection and trimming algorithms are put forward.A series of local coordinate systems are set up and the surface is divided into many small patches.Each control vertex relates to a series of local parameter coordinates in the coordinate system it belongs to.The meshes are splitting with revised skirt-removed subdivision approach and intersecting faces are found among related faces.Then initial intersections and their parameters are gotten based on the Divide-Conquer idea and precise results can be obtained with iteration method.According to the trimming region required，the direction of each intersect line is reset.The control mesh facets of the trimmed surface are classified into three types：reserved facets，trimmed facets and discarded facets.Trimming domain of the trimmed facets are set automatically.Examples indicate simpleness and efficiency of this method.

Key words: subdivision surfaces, intersection, trimming, parametrization