VRayFastSSS2 is a material primarily designed for rendering translucent materials like skin, wax, marble, etc. The implementation is based on the concept of BSSRDF originally introduced by Jensen et al. (see the references below). It is an approximation of the sub-surface scattering effect observed in the physical world, while still being fast enough to be used in practice.
VRayFastSSS2 is a complete material with diffuse and reflection components that can be used directly without the need of a VRayBlendMtl material. To be more specific, the material is composed of three layers: a reflection layer, a diffuse layer, and a sub-surface scattering layer. The sub-surface scattering layer is comprised of single and multiple scattering components. Single scattering occurs when light bounces once inside the material. Multiple scattering results from light bouncing two or more times before leaving the material.
