Chapter 4 discusses the usage of two basic geometric reconstruction method ( bezier and b - spline surfaces reconstruction ) in virtual cad system based on the milti - hierarchical mesh model . bezier reconstruction method introduces li lixin ' s new c - t algorithms which adopts bezier patches on rectangles . b - spline reconstruction follows floater ' s shape - preserving parametric method using double cubic b - spline surface and extends it into non - four - side areas by inducing corner vertices and optimizing the sheer - shape boundary which amends the boundary distortion of the reconstructed surfaces 通过引入单边退化概念，进行四边域上的bezier曲面重建；通过引入保形参数化映射，讨论双三次b样条曲面重建方法；在网格曲面四边拓扑分析的基础上，给出了基于深度搜索的角点求取方法，拓展了floater双三次b样条曲面重建的应用范围。
