空间动态可变材质的交互式全局光照明绘制  

Interactive Global Illumination Rendering with Spatial-Variant Dynamic Materials

作　　者：孙鑫[1] 周昆[2] 石教英[1] 

机构地区：[1]浙江大学CAD／CG国家重点实验室,浙江杭州310027 [2]微软亚洲研究院网络图形组,北京100190

出　　处：《软件学报》2008年第7期1783-1793,共11页Journal of Software

基　　金：the National Basic Research Program of China under Grant No.2002CB312105(国家重点基础研究发展计划(973))

摘　　要：提出了一种空间动态可变材质的交互式全局光照明绘制算法.如果在绘制过程中允许用户对物体的材质作修改,并且对一个物体的不同部分的材质作不同的修改,则称为空间动态可变材质.由于最终出射的辐射亮度和材质呈非线性关系,因此现有许多交互式全局光照明算法不允许用户修改物体的材质.如果一个物体各部分的材质可以不相同,那么材质对最终的出射的辐射亮度的影响更为复杂,目前没有任何交互式全局光照明绘制算法能够在绘制过程中对一个物体不同部分的材质作不同的修改.将一个空间动态可变材质区域划分成许多子区域来近似模拟,每个子区域内部材质处处相同.光在场景传播过程中可能先后被不同的子区域反射,并以此将最终出射的辐射亮度分为许多部分.用一组基材质来线性表示所有的材质,这组基材质被赋予场景中的所有子区域,从而得到不同的基材质的分布.预计算所有这些基材质分布下的各部分最终出射的辐射亮度.绘制时根据各子区域材质在基材质上的系数组合相应的预计算数据,就能交互式绘制全局光照明效果.This paper proposes a method of interactive global illumination rendering with spatial-variant dynamic materials under complex illumination. With the spatial-variant dynamic materials, the materials of the scene can be changed while rendering, and the changes to different parts of an object can be different. The non-linear relationship between materials and out-going radiance prevents users from changing the materials with most of existing interactive global illumination rendering algorithms. If different parts of an object are covered with different materials, the materials take much more complex effects on the out-going radiance. So there is still not an interactive global illumination rendering algorithm allow users to make different changes to different parts of an object. This paper approximates a region with spatial-variant dynamic materials by dividing it into numbers of sub-regions, the material in each sub-region is uniform and consistent. The radiance transferred in the scene may be reflected by different sub-regions successively, and the paper divides the out-going radiance according to different sequences of the reflection sub-regions. This paper also represents all materials with a linear basis, and applied the basis to all sub-regions to get all different distributions of the material basis. This paper precomputes all parts of radiance of all material basis distributions. In rendering process, it uses the materials＇ coefficients of basis to combine corresponding precomputed data to achieve the global illumination effects with interactive performance.

关 键 词：空间动态 全局光照明 双向反射分布函数 路径跟踪 绘制方程 主元分析法 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]