中文摘要：

点集模型作为一种新兴的三维几何形体表示形式,近年来备受关注.本文运用点集法向计算与凸包构建等技术,对原始点集模型进行直接可视性计算,并利用可见性计算的结果对点集模型进行基于视点的绘制.算法首先对原始模型进行基于视点的精简,剔除大部分不可见点;再对精简后的模型进行球面对称变换,并构建变换后点集的凸包,进而提取出可见点集;最后运用真实感图形绘制技术实现可见点集的快速绘制.实验证明,本文算法能够快速地计算点集模型中采样点的可见性.该算法可应用于点集模型基于视点的绘制与曲面重建,以及点集模型的阴影绘制等领域.

英文摘要：

As a novel representation technology of 3D geometric shapes,point-based model has attracted more and more interests of researchers in computer graphics society in recent years.In this paper,we present an algorithm for calculating direct visibility of point-based models by using techniques such as normal computation and convex hull construction,and the point-based models can be rendered in view-point dependent way.In our method,original point-sets are first simplified to remove some of invisible points and then transformed to construct its convex hull.At last,the visible points,in original point sets are rendered using realistic rendering techniques.The experiments show that our method can directly calculate visibility of point sets well.This method can be used in various fields such as viewer-dependent drawing and reconstruction of point sets and shadow drawing.