如下是帮助里提供的定义 %&&;06GU} BRDF:Bi-directional Reflectance Distribution Function. It is the scattered radiance from a surface (reflective scattering) per unit incident Irradiance, and thus has units of inverse steradians (1/sr). The BRDF is defined as the differential scattered radiance per unit incident Irradiance. G]E-2 _t7 BSDF:Bi-directional Scattering Distribution Function and is a generic term which is used to refer to BRDF and BTDF. Uq=!>C8 BTDF:Bi-directional Transmittance Distribution Function. It is the scattered radiance through a surface per unit incident Irradiance. a+e8<fM yT m<GJ1)%3i 具体参数怎么选取需要自己去多尝试,手册里虽然有公式,但很抽象。