加快光线跟踪计算的网格优化划分  

Optimizing Grid Resolutions for Ray Tracing

作　　者：李静[1] 王文成[1] 吴恩华[1,2] 

机构地区：[1]中国科学院软件研究所计算机科学国家重点实验室,北京100190 [2]澳门大学科学技术学院电脑与资讯科学系,中国澳门

出　　处：《计算机辅助设计与图形学学报》2008年第8期968-977,共10页Journal of Computer-Aided Design & Computer Graphics

基　　金：国家“八六三”高技术研究发展计划(2006AA01Z306);国家自然科学基金(60773026)

摘　　要：网格是一类重要的光线跟踪加速结构,其结构简单、能快速创建.但是网格划分的尺度对光线跟踪的效率有很大的影响.针对此,提出一种代价预估计算方法,以度量网格划分对光线跟踪计算效率的影响,并由此计算网格优化划分的分辨率.首先根据模型类型和网格使用方式计算几种场景参数,分别预估网格创建、跟踪和空间的开销;然后根据不同应用需求,以相应的预估代价最小来进行网格的优化划分.与已有方法不同,文中方法考虑了场景中面片分布类型对网格划分的影响,提高了度量计算的精度;还综合考虑了网格创建时间、空间需求等因素,以便度量计算能根据绘制任务的不同进行相应的优化处理.该方法能更好地提高绘制效率,特别是能处理动态场景和面片非均匀分布的复杂场景,而这些是已有方法难以处理的.实验结果表明,文中方法的预估网格优化分辨率与实际的最优分辨率很接近,优于已有的类似工作.Grid is one of the important structures for speeding up ray tracing, and it can be easily constructed. However, the grid resolution affects the efficiency of ray tracing greatly. A cost prediction method is presented in this paper to measure the cost of ray tracing with respect to the grid resolution, and the technique is further developed to compute the optimized grid resolution for a specific rendering task via ray tracing. Our new method first calculates some parameters about the scene according to the model type and the manner to use grids, to predict the time cost and related storage requirement on grid construction, ray tracing via the grids. An optimization process is then applied to choose an appropriate gird resolution by minimizing the cost predict function for specific rendering tasks. Unlike existing methods, our new method takes into account the distribution features of facets in a scene, thus increasing the prediction accuracy. Experimental result shows that our method can be used to compute an optimized grid resolution, almost close to the best grid resolution for ray tracing various scenes.

关 键 词：代价预估 均匀网格 光线跟踪 动态场景 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]