Realistic Rendering in “Details”

Abstract

Rendering is far from solved. Even today, the rendered results still look artificial and overly perfect. To make rendering more realistic, we need details. However, rendering a complex surface with lots of details is far from easy. Traditionally, the surface microstructure is approximated using a smooth statistical distribution, but this ignores all the details on the surface, completely eliminating the "glinty" visual effects that are easily observable in the real world. While modeling the actual surface microstructure is possible, the resulting rendering problem is prohibitively expensive using Monte Carlo point sampling. We consider the highly complicated distribution of normals on a surface patch seen through a single pixel, and evaluate this actual distribution efficiently with closed-form solutions, in both geometric and wave optics. Results show complicated, temporally varying glints from materials such as bumpy plastics, brushed and scratched metals, metallic paint and ocean waves-bringing the interesting and important details to Computer Graphics for the first time.