关键词: 全局照明, 光线跟踪, 半球谐函数, 双向反射率分布函数

Abstract: This paper presents a ray tracing-based method to speed up the global illumination with glossy surfaces by using hemispherical harmonics.In this method,the radiance samples have been achieved on the surface,then they are calculated and put into cache memory.Lastly other points around the sample points are interpolated.The incoming radiance at a point is represented with the hemispherical basis.BRDFs are defined on the Cartesian product of hemispheres.A handy method is used to calculate the radiance gradient at a point.It shows that our method improves the global illumination calculation speed much more.It has more application fields such as illumination project,high quality animation and virtual reality rendering.

Key words: global illumination, ray tracing, hemispherical harmonics, Bidirection Reflectance Distribution Function（BRDF）