利用球谐方法分散计算场景的全局光照

作为一种特殊的光照模型,辐射度在图形学中有着重要的应用.然而,由于其计算的复杂性,辐射度方法一直得不到广泛的应用,特别是在动态场景中.提出一种基于辐射度算法的全局光照实时加速算法,在原有基于点采样进行场景的全局光照近似的基础上,提出了不同的点采样计算方法,以提高辐射度方法对动画场景的适应性.算法对场景中的物体建立六面体包围盒,并在包围盒各顶点设置采样点,这样就可以在环境变化对其光照影响不大的情况下采用原有的计算结果,实现辐射度算法在动态场景中的计算加速.同时,对场景中的每个物体的光照,利用立方体映射计算直接光照;而对物体间的能量交换采用点采样方法进行近似计算并利用附近采样点的光照插值作为物体的光照.实验结果表明,该算法可以减少大量的间接光照计算,提高了辐射度算法的效率.

Dispersive Calculation of Global Illumination Based on Spherical Harmonics Method

The radiosity illumination model plays an important role in computer graphics. As the calculation in the traditional radiosity method is time consuming, it is not suitable for dynamic scenes. In the paper we present a system based on the radiosity approach to speedup the calculation of global illumination. The algorithm follows the thoughts of using point sampling to simulate global illumination, while the sampling process is special so that the radiosity solution could be more adaptive in a dynamic scene. To every object inside the scene in the method, reference points are setup just at the vertices of the bounding box. When the scene is only slightly changed, the sampling result can be reused to reduce computation. The direct light is computed by cube-mapping and the energy exchange between objects is simulated by a trilinear-interpolation among the reference points. Experiments show that the method can accelerate rendering with less indirect illumination calculation required.