Possible indirect lighting problem?

Hi, I posted this on the archviz forum but I want to share on the main forum as well. Attached are some images. One to show the overall scope of my project, one to address the problem I am having and my light-mass settings. The interior image shows the problem I am having. All the surfaces that face downward are dark. This is happening inside as well as on out side surfaces that face downward. It seams they are not getting any indirect lighting. Any ideas as why this is happening?



Are you sure things are set up correctly? The lighting on the interior should be pretty much black since you have no lights in there, I’m not seeing any kind of shadowing. So either those meshes aren’t static, or your lights aren’t static/stationary or you haven’t built your lighting.


I have built the lighting. All my meshes are static. No interior lights yet. My directional light is movable and so is my skylight. I have a day/ night cycle running. I have seen renderings online where no interior lights are being used yet some light still gets in and bounces around to at least give a little light to the ceiling. I am not sure my lighting is set up correctly because things look strange on the interior. And I have been reading about the differences between static vs. dynamic lighting but not quite understanding it completely. I have taken out the day/ night cycle and used a static directional light and the ceilings are still black.


You are using dynamic lighting which does not provide light bouncing. You’ll need to use light propagation volumes, DFGI, or VXGI if you need GI and dynamic lighting. Those options are pretty performance demanding, you could also try to fake it with a upward facing directional light that doesn’t cast any shadows. For archviz, I’d normally suggest just baking the lighting for the best visual results.

Yes, I need GI with Dynamic lighting. I have a fairly hefty machine. 64 gig of ram and 40 cores. How do I go about setting up my scene using DFGI or VXGI? My clients really like the idea of the day/ night cycle slowly running in the background.

Or by performance demanding do you mean video playback? So video card demanding?



They are very demanding on the GPU. LPV is the least demanding, then DFGI, then VXGI.

LPV - It’s what CryEngine 3 used until recently
Unreal Engine 4 Wiki

It’s integrated into the Engine, I think any build of UE4 should work.

DFGI - Very new feature, new tech, kinda blotchy
Main Thread

It’s integrated into the Engine, use version 4.8 of the engine or newer, it’s being upgraded frequently.

VXGI - Nvidia’s voxel based dynamic GI solution - Requires a newer generation Nvidia Geforce GPU (I believe 700 series or newer)
Main Thread

Github download (you have to be logged in)
Example video