Shell radiance texture functions

The appearance of an inhomogeneous translucent material depends substantially on its volumetric variations and their effects upon subsurface scattering. For efficient rendering that accounts for both surface mesostructures and volumetric variations of such materials, shell texture functions have precomputed irradiance within a volume with respect to incoming illumination, but even with this irradiance data a fair amount of runtime computation is still required. Rather than precompute volume irradiance, we introduce the shell radiance texture function (SRTF), which relates incoming illumination more directly to outgoing surface radiance by representing a set of subsurface transport components from which surface radiance can be calculated without ray marching or runtime evaluation of dipole diffusion. Using this precomputed SRTF information, inhomogeneous objects can be rendered in real time with distant local lighting or global lighting.