S(wi)SS: A flexible and robust sub-surface scattering shader

S(wi)SS is a new, flexible artist friendly multi-layered sub-surface scattering shader that simulates accurately subsurface scattering for a large range of translucent materials. It is a physically motivated multi-layered approach where the sub-surface scattering effect is generated using one to three layers. It enables seamless mixing of the classical dipole, the better dipole and the quantized diffusion reflectance model in the sub-surface scattering layers, and additionally provides the scattering coming of front and back illumination, as well as all the BSDF components, in separate render channels enabling the artist to either use them physically accurately or tweak them independently during compositing to produce the desired result. To demonstrate the usefulness of our approach, we show a set of high quality rendering results from different user scenarios.