3ds max Lighting Adjusting light distribution But for a rectangle or area light, we want a different light distribution type. From the pull-down list, switch it over to uniform diffuse and as you do it, notice what happens to the intensity. With a uniform diffuse light distribution type, now the area light behaves the way we expect. It’s sending light only out in one direction. And I can orbit around there, and additionally, the luminance value changed; it was 2000 and now it’s 500.
But the overall amount of illumination coming from the center of this area light has remained pretty much constant. So this got changed behind our back, but that’s okay. So that’s how to set up a standard area light and as we change its dimensions in the length and width here we can see that we can cover a larger area. The overall amount of illumination will remain constant.