Specifies the number of samples the Progressive Lightmapper uses when sampling indirect lighting from the skybox. (Editor only).
Indirect lighting only uses 1 environment sample per bounce per indirect sample. However, this can sometimes be insufficient and sampling the environment can then cause noise in indirect lighting. Increasing this value will increase the number of skybox samples fired per indirect bounce, which will help reduce noise.
The range is 8 through 1,000,000,000. Higher values result in increased quality lightmaps, but baking takes more time. The default value is 256.
This setting affects lightmaps generated by the Baked Global Illumination system. It applies only when using the Progressive Lightmapper.
When Unity serializes this LightingSettings object as a Lighting Settings Asset, this property corresponds to the Indirect Samples property in the Lighting Settings Asset Inspector.
Additional resources: Lighting Settings Asset.