2008

For volumetric lighting to work with light tracing, Bounces must be greater
than 0.
Volumes [amount] Multiplies the amount of light regathered from volumetric
lighting effects. Increase to increase their impact on the rendered scene,
decrease to decrease their effect. Default=1.0.
Increasing the Volumes value increases the effect of volumetric lighting in the rendering.
Adaptive Undersampling group
These controls can help you speed up rendering time. They reduce the number
of light samples taken. The ideal settings for undersampling vary greatly from
scene to scene.
Undersampling initially takes samples from a grid superimposed on the pixels
of the scene. Where there is enough contrast between samples, it subdivides
that region and takes further samples, down to the minimum area specified
by Subdivide Down To. Lighting for areas not directly sampled is interpolated.
Default Scanline Renderer Rollout | 5973