基于层次细节模型的遮挡裁剪算法

遮挡裁剪和应用层次细节模型是两种有效的三维复杂场景渲染加速算法，为了快速地进行三维复杂场景的渲染，提出了一种结合层次细节模型与遮挡裁剪技术的算法框架，该算法首先在预处理阶段，将场景划分成不同空间层次结构；然后在运行时刻，对较高的空间层次，可应用遮挡裁剪技术判别场景的可见性，并裁剪掉不可见场景部分，而在局部的较低层次上，则应用网格简化方法来选择适当的模型层次细节，实验结果显示，该算法取得了较好的加速性能。

An Occlusion Grid Culling Algorithm Based on LOD Models

Occlusion culling and LOD(Level of Details) both are effective techniques in accelerating the rendering process of 3D large scene. An algorithm framework which integrate occlusion culling and LOD is proposed in this paper. It partitions the scene volume into a hierarchical structure during the preprocess stage, and in runtime, it uses occlusion culling in the high level to cull the invisible scene, while view-dependent simplification are used in the low level to show the detail. This algorithm is mainly based on Luebke's work of mesh simplification and Heinrich's work of lazy occlusion grid culling in the image space, it extends the data structure of 'vertex tree' to support occlusion culling and also uses an occlusion grid buffer to reduce the number of expensive occlusion queries at pixel-level. Experiment result shows that significant speedup is achieved through our algorithm.