尽管当前基于全局光照模型的图形绘制方法可以渲染出高质量的图象，但因为其计算量巨大，难以适用于诸如建筑物漫游、虚拟现实等对绘制速度有严格要求的场合.为此引入光学映射虚物体的概念，利用构建在联网PC机上的集群系统，并行创建反射和折射虚物体，然后利用集群中各节点的图形加速硬件，像处理实际三维物体一样绘制这些虚物体，可以快速地绘制出反射 /折射效果的图象.实验结果证明，该方法利用 CU P的计算能力和图形硬件的加速特性实现了真实感图形的高性能绘制，特别适用于诸如建筑物漫游、计算机动画和虚拟现实等要求交互式绘制的场合

Current rendering algorithms of global illumination models can generate photo-realistic images, but the high computing cost may discourage their applications in walk-through and virtual reality etc. Especially, rendering specular reflections and refractions is always a problem in computer graphics community. In this paper, virtual optical-mapping objects are introduced, and a unified method for generating virtual objects of reflections and refractions is proposed. The virtual objects are treated in the same way as real objects in the scene, so the reflection and refraction images can be rendered by the graphical hardware. Cluster based connected PCs is utilizes as parallel platform, and task scheme and load balance are discussed. Virtual objects are generated by CPU and rendered by graphical hardware. So, this method utilizes simultaneously both CPUs and graphical hardware on nodes of clusters to achieve high performance rendering. In the last, examples demonstrate this method is powerful for interactive applications such as real-time walk-throughs in buildings, animation and virtual reality.