保持尖锐特征的混合细分曲面生成

基于混合细分模式，提出了细分曲面尖锐特征生成方法，通过对初始混合控制网格上要生成的各种尖锐特征的顶点和边分别作标记，然后局部修改细分规则进行迭代细分，实现了光滑混合曲面上产生折痕、角点、刺点、尖点的尖锐特征效果，并对尖锐特征处的局部细分矩阵进行了详细的特征分析。实验结果表明，该文算法效果好，能很好地保持模型的尖锐特征。

Generation of hybrid subdivision for holding sharp features

Previous methods for generation of sharp features of subdivision surfaces are based on that initial control meshes are either triangle-only meshes or quad-only meshes.However,in engineering surface modeling,general shapes designers often want to model certain regions with triangle and quad hybrid patches structure.In order to overcome the defect in generation of sharp features utilizing traditional approaches,in this paper,we propose a method for creating sharp features on hybrid subdivision surfaces.By locally modifying hybrid subdivision rules,sharp features such as crease,corner,dart and cusp are generated.We also give eigenanalysis of local subdivision matrices for the piecewise smooth subdivision rules that include sharp features,and convergence and smoothness of the limit surface are discussed.Examples demonstrate the efficiency of our method.