一种辐射度全局光照网格模型的简化方法*

全局光照模型计算通常将环境中的表面分解得足够细,以精确地捕捉由于物体间相互遮挡所引起的阴影效果及其他一些光照效果.因而,一个复杂场景经全局光照计算后,其模型复杂度远远超出了当今图形工作站的实时绘制能力.给出了一种辐射度全局光照网格模型的简化方法.算法首先根据辐射度计算的特点以及人眼的视觉特点,提出以辐射度最大相对变化值为准则,以面片合并法实现全局光照网格模型的第1步简化,将原辐射度全局光照网格模型简化为能量相对变化在用户定义误差范围内的一些超面区域.然后利用顶点删除法实现超面区域边界的简化,进一步加大原网格模型的简化程度.试验表明,这种算法不仅能有效地简化辐射度全局光照网格模型,而且能较好地保持原光照网格模型的特征.

A Simplification Method for Radiosity Global-illumination Meshes

The solution to the global illumination problem using radiosity method is usually represented by an illumination meshes, which are frequently very finely tessellated in order to capture shadow boundaries and other significant illumination features. So the geometry complexity of a complex scene with global illumination effect is beyond the capability of the current computer graphics workstation. In this paper, an automatic method is presented for simplifying the meshes produced as the solution to global illumination problem using radiosity method. Based on the character of the illumination meshes produced by radiosity and the characteristic of human eyes, it simplifies first by merging faces with maximum relative radiosity difference below the threshold that users define. And then the vertices on the perimeters of the merged face are deleted to further simplify the original meshes model. The model simplification samples based on these methods are given and the results show that the algorithm only significantly reduced the complexity of original meshes model, but also performed well to capture the coherent shadow discontinuity feature of illumination meshes.