March 16, 2012, 04:12:48 am
So you want it to just self-illuminate, and not cast light and shadow?
If so, and you have a separate surface for the light position/area/cove then just use Color Material and Overbright or Standard Material with a single color texture and Emissive. You can ramp the emissive so it appears to be luminating without casting light, just a matter of getting the settings right for the render and other image or video settings used.
You can always make a 'light' based object for the cove without it being the cove and apply illumination requirements to that, or separate surfaces to apply different color, depending on how much change is needed.
If you need to cast light (and shadow), then you need to use lights, there's no rectangular area light, but has been suggested.