Specifies the threshold the Progressive Lightmapper uses to filter direct light stored in the lightmap when using the A-Trous filter. (Editor only).
The range is 0 through 2. The default value is 0.5. A higher value will increase the threshold, reducing noise in the direct lighting component of the lightmap. Too high of a value can cause a loss of detail in the lightmap.
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 Filtering > Direct Filter > Sigma property in the Lighting Settings Asset Inspector.
See Also: Lighting Settings Asset.