本文利用收缩包围算法给出了一种对无结构三角网格拟合出Catmull-Clark细分曲面的算法，根据Catmull-Clark细分的特点，具体设计了松弛算子和吸引算子.通过提出用于三角形合并的保凸约束和平坦度约束，不但使得构造出的基网格保持了三角网格中的尖锐特征，而且细分后网格的边不会自交.通过引入回插细分、给出四边形网格下的吸引算子和松弛算子，使得曲面在重构过程中无需识别网格中的尖锐特征，能够对整个网格采用统一的方式进行处理.基网格的构造、网格顶点的调整、细分模式的选取和重构曲面的误差分析是算法的主要组成部分.

Based on the shrink-wrapping algorithm, this paper presents an approach to reconstruct Catmull-Clark subdivision surfaces from unstructured triangular meshes. Attracting / relaxing operators are designed using properties of Catmull-Clark subdivision. By presenting the reserving convexity constraint and the flat degree constraint, the base mesh can reserve sharp characters in the simplified triangular mesh and mesh edges do not cross after the base mesh is subdivided. By using these methods, such as the push-back subdivision scheme, the attracting operator and the relaxing operator in quadrangular meshes, the approach need not distinguish sharp characteristic while reconstructing surfaces. It can deal with the whole mesh by the single algorithm. Main components of the approach are constructing base meshes, adjusting vertices of subdivision meshes, choosing subdivision schemes and analyzing errors of subdivision surfaces.