by Chris Tyler:
Adaptive Shadow Sampling in version 8.1
This tutorial shows differences in how version 8.1 handles shadow regions for both global illumination and shadows from point light sources as determined by the Adaptive Shadow Sampling parameter. Improvements to this area help to create cleaner looking images in shadow regions. It explains value ranges useful for Adaptive Shadow Sampling. The layered PSD image shown in the first video is included for closer examination.