Realistic looking human skin for computer-generated characters has become more and more necessary in film. Pixar’s Finding Nemo and PDI/Dreamworks Shrek 2 have set the standard on what audiences expect to see on any human characters in CG films on the big screen. Tomson [2003] notes that people are particularly perceptive to when looking at human characters even when the character design doesn’t call for strict realism. People still get the feeling that something is wrong when a suitable model for human skin is not implemented.

Subsurface scattering is a technique used widely for developing models for human skin simulation. While much research has been conducted in the area of subsurface scattering, prior to 2001, most of this research was focused on developing models for the bi-directional reflectance distribution function (BRDF) which is a simplification of the more general bi-directional surface scattering distribution function (BSSRDF) (Jensen et al. 2001, p. 511). In this document, I will be discussing the theory behind BRDF and BSSRDF as well as methods for approximating subsurface scattering as described by SIGGRAPH papers submitted in recent years. I will also include a case study of the implementation of a subsurface scattering model for Renderman.