三角面片模型中几何特征的提取

虚拟设计中采用的是由三角面片表示的产品模型，虽然三角面片模型能很好地满足VR实时性的要求，但三角面片模型损失了模型的几何信息和拓扑信息，使得虚拟设计中的产品模型不能直接用于后续产品的详细设计。提出的由虚拟模型到CAD模型的提取算法可以很好地解决这一矛盾。该算法首先对模型进行切片，然后提取个切片中模型的边界点，根据这些边界点和三角面片的顶点重构模型的边界，再进一步形成模型的拓扑结构。在边界信息的基础上拟合模型的表面，从而构造出精确的表面模型。

Extraction of geometric features from model of triangular surface piece

The product model expressed by triangular surface slices is being adopted in virtual design. Although model of triangular surface slices could satisfy nicely the requirements of VP in real-time, yet the model will lose its geometric information and topologic information, thus makes the product model of virtual design could not be applied directly to detailed design of follow-up products. The extraction algorithm from virtual model to CAD model being advanced could solve this contradiction quite nicely. Firstly, this algorithm carries out cutting upon the model into slices, and then extracts boundary points from every slices of the model. According to the boundary of model being constructed from these boundary points and triangular surface slices, the topological structure of model is formed in a further step. Outer surface of model is matched on the basis of boundary information, thus the precise surface model is constructed.