Understanding the Principles of Light Behavior - Photographic Rendering with V-Ray for SketchUp - page 173

Note
The V-Ray Rectangle and Sphere area lights also of course make exclusive use
of the Inverse Square decay type.
Although we have already seen a render of our 30 x 30 feet square room with the
Omni light set to use Inverse Square decay, for the sake of completeness, we can
again include the image here.