如下是幫助里提供的定義 AG G xx?I 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. N=@8~{V. BSDF：Bi-directional Scattering Distribution Function and is a generic term which is used to refer to BRDF and BTDF. 2Fbg"de3- BTDF：Bi-directional Transmittance Distribution Function. It is the scattered radiance through a surface per unit incident Irradiance. {J;(K~>?m