Whether the Progressive Lightmapper prioritizes baking visible texels within the frustum of the Scene view. (Editor only).
When this is set to true, the Progressive Lightmapper prioritizes baking texels within the Scene View. When set to false, all lightmapped texels throughout the Scene have the same priority. .
Enabling this feature means that the lightmapper will attempt to finish visible lightmap texels within the frustum of the Scene View camera before work begins on the rest of the Scene.
This helps provide faster visual feedback, however it may increase the overall bake time.The default value is true.
This setting affects lightmaps generated by the Baked Global Illumination system. It only applies to the the Progressive Lightmapper.
When Unity serializes this LightingSettings object as a Lighting Settings Asset, this property corresponds to the Progressive Updates property in the Lighting Settings Asset Inspector.
Additional resources: Lighting Settings Asset.