光线追踪遮挡检测算法

遮挡检测是真正射影像制作中关键的一步。本文根据光线追踪法遮挡检测的原理，将TIN数据分为基本面三角网和墙面三角网分别进行遮挡检测，对格网数据则采用光线与DSM表面的高程差值的变化规律来确定遮挡关系,从而得到改进的遮挡检测算法。实验证明改进后的算法能够准确地检测出复杂建筑物的遮挡区域。特别是格网数据的光线追踪遮挡检测更简单、更有效。

Ray-tracing Based Occlusion Detection Algorithms

Occlusion detection is a critical step in the true orthophoto procession. According to the principle of Ray-tracing occlusion detection, TIN data are divided into the base triangular network and wall triangular network which are processed separately, for grid data the variation of elevation difference between the ray and DSM is used to determine occlusion relationship, thereby obtaining improved occlusion detection algorithms. Experiments show that the algorithms can precisely detect occlusion area of complex buildings. Especially the grid-based Ray-tracing occlusion detection is more simple and effective.