Realistic human face rendering for "The Matrix Reloaded"

The ultimate challenge in photorealistic computer graphics is rendering believable human faces. We are trained to study the human face since birth, so our brains are intimately familiar with every nuance and detail of what human skin is supposed look like. The challenge of rendering human skin is further complicated by some technical issues such as the fact that skin is a highly detailed surface with noticeable features in the order of ~100 microns and the fact that skin is translucent. On The Matrix Reloaded we had to create completely photorealistic renderings for most of the principal actors including Keanu Reeves, Lawrence Fishborne, and Hugo Weaving.