I came across this simple trick purely by accident when setting up lighting for a room full of furniture. I ended up supplying indirect/direct lighting for an entire scene with a single light and a plane. The great part of this technique is that it renders really fast.
For a test of how this works, setup a standard scene with a V-Ray Plane that has a checker diffuse. Add a teapot to the center of the scene, with any material. Lastly, add a standard Target Spot above the scene. Crank up the intensity multiplier to 3.0. The scene should look a little like this:
Now we’ll add a simple plane and place it above the teapot, somewhere between the teapot and the target spot. Make it’s color a light brown by adjusting it’s default color in 3ds Max at the top right of the interface where you rename objects. I’m not talking about applying any material at all. This yields:
No surprises here. But as we have V-Ray as our renderer, we will enable indirect illumination under V-Ray::Indirect Illumination (GI). Be sure that the target spot has VRayShadow enabled:
Pretty cool, eh? Once you make a plane illuminate with the color you like, you can put objects between it and your subject to filter the light to a shape more consistent to what you’re looking for, such as a skylight, or even lights in a suspended ceiling.
Check out what the lit plane looks like from below:
But you’d think that a plane, which has 0 thickness, could be placed in any orientation and still allow light to radiate from it, right? Wrong! Inverted, the scene is:
Obviously, the plane needn’t be lit by a target spot, and not necessarily used to add atmospheric lighting as done here. Have fun!