层次包围盒与GPU实现相结合的光线投射算法  

A Ray Casting Algorithm Based on Hierarchical Bounding Volumes and GPU

作　　者：邹华[1] 高新波[1] 吕新荣[1] 

机构地区：[1]西安电子科技大学电子工程学院,西安710071

出　　处：《计算机辅助设计与图形学学报》2009年第2期172-178,共7页Journal of Computer-Aided Design & Computer Graphics

基　　金：国家自然科学基金(60771068);国家"九七三"重点基础研究发展计划项目(2006CB705700);教育部长江学者和创新团队支持计划(IRT0645)

摘　　要：针对目前基于GPU的光线投射算法中参数确定复杂的缺点,提出一种快速确定投射光线参数的算法,并利用层次包围盒技术对整个绘制过程进行加速.该算法利用离屏渲染技术,仅通过绘制体数据包围盒表面就能获取投射光线的参数;为了跳过对绘制结果无贡献的空体素,逐层对体数据进行分解,并生成层次包围盒树来存储对应子体数据的相关信息,通过遍历包围盒树,判断对应子体数据是否被绘制或跳过来缩短投射光线在体数据中的有效采样长度,从而实现了光线积分加速.实验结果表明,与同类算法相比,该算法预处理时间较短,在增加存储容量较小的同时获得了平均3.0的加速比,具有更好的实用性.In the traditional GPU-based ray-casting algorithm, determination of ray parameters is a time consuming task. To improve rendering process speed in this aspect, the paper proposes an improved method to estimate the rendering parameters and a more efficient rendering technique based on hierarchical bounding volumes. By using off-screen technique, the start points and end points of rays can be easily estimated only by rendering the bounding box of volume data. For skipping the empty voxels which have no effect on the rendering result, volume data is subdivided level by level and the relevant information of sub-volumes is stored in the nodes of bounding box tree. Based on the information of nodes, the bounding box tree is traversed to determine whether the corresponding subvolumes should be rendered or skipped, to shorten the length of ray integral and accelerates the volume rendering. Experimental results show that the proposed method is more efficient than the available methods with less pre-processing time and an acceleration ratio of 3.0.

关 键 词：GPU 层次包围盒 空间跳跃 光线投射 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]