I am far from an expert on this, but this is my experience so far with 3Delight renders of indoor scenes:
If you are using UE indoors with mode set to “ambient” this produces renders that look like bad comic books. In “ambient” mode you have to turn UE down to a very low intensity and only use the UE light to contribute a small part of your light in order to get a decent result.
If you are using UE in “Occlusion w/Soft Shadows” mode, then you have to set trace distance parameter to about 100. I think the default is 500, which is good for outdoor scenes, but indoors it causes UE to create very dark scenes.
Recently I have been using a different way for lighting indoor scenes in 3Delight that does not use UE. The problem with lighting indoor scenes is creating the ambient light. You can put an UberArea light outside the windows to simulate the fact that real sunlight would be scattered and coming in the window from all directions, not just in the direction of your spot light or distant light. The Ambient light though would also reflect off the interior surfaces, especially any light colored surfaces. An unbiased render engine like Lux will trace all of that reflection off the interior surfaces, but 3Delight doesn’t do this very well.
In 3Delight you need to create artificial ambient light. This is what UE does, but I have discovered you can do the same thing with distant lights. A distant light with shadows turned off will go right through the walls and light up the interior. I set these ambient distant lights to be diffuse only, so they do not produce any specular highlights on anything. I typically use 4 of them, set at Y rotations of 0, 90, 180 and 270 with a small negative X rotation so they are pointed slightly down. This gives me “ambient light” coming from all directions. You have to turn the intensity down on this lights to 10-30% range depending on how much ambient light you want in the room. I have also added one distant light pointing straight up to get some “ambient” light on the ceiling.
As I said, I’m far from and expert, but I have like the results I’ve gotten using distant lights coming from all directions to model both indoor and outdoor ambient light.
Excellent advice. I’ve noted that the default in Studio 4.5 for maximum trace distance has been lowered to 150. Perhaps for this reason…but it also makes rendering a little faster.
For people who aren’t as wedded to 3D renders looking, well, real, there is the matter of the building walls and roof. You can set them to not cast shadows and that lets the light flow in unimpeded. Often model makers make walls and the roof ‘removable’ for camera angles. If you utilize that, it also causes the sunlight, from whatever source, to enter the space.