2008

Bright polygons in the scene can create a “sparkle” effect of bright spots.
These bright spots are artifacts not of the number of samples cast, but rather
of the presence of bright polygons in your scene. During the Initial Quality
stage, this bright energy gets bounced in random directions, leading to a
“sparkle” effect. Typically you can detect these polygons before regathering.
During the final Regathering stage, bright spots can be avoided by setting
Clamp Values somewhat below the luminance of these bright surfaces and
spots.
6024 | Chapter 18 Rendering