Chapter 16. Real-Time Approximations to Subsurface Scattering
https://developer.download.nvidia.cn/books/HTML/gpugems/gpugems_ch16.html
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most shading models used in real-time graphics today consider the interation of light only at the surface of an object. in the real world, however, many objects are slightly translucent: light enters their surface, is scattered around inside the material, and then exists the surface, potentially at a different point from where it entered.
much research has been devoted to producing efficient and accurate models of subsurface light transport. although completely physically accurate simulations of subsurface scattering are out of the reserch of current graphics hardware, it is possible to approximate much of the visual appearance of this effect in real time. this chapter describes several methods of approximating the look of translucent 半透明的 materials, such as skin and marble 大理石, using programmble graphics hardware.
16.1 the visual effects of subsurface scattering
when trying to reproduce any visual effect, it is often useful to examine images of the effect and try to break down the visual apperance into its constituent 构成的 parts.