Hi, I’m doing some experiments with large numbers of instance static meshes 200K+ and the only real barrier to pulling this off appears to be Lumen GI.
I can render 200K+ instances without issue at 120fps as long as I have Lumen GI turned off in the scene.
As soon as I have Lumen GI turned on the frame rate drops to single digits.
Is there any way to exclude these instanced static meshes from the Lumen GI pass to get around this performance bottleneck?
Hello ,
There is no way to exclude specific materials or objects from Lumen GI, however you can use a post processing volume to significantly modify what Lumen does within that volume. You can even turn GI off entirely within the volume in question, or simply lower the quality. Reflections and shadows are likely the main reason for your loss of performance, so try tweaking those first. See the image below for some of the options I think you can make use of.
Please let me know if this solution works for you!
You can exclude them from the Lumen scene by disabling “affect distance field lighting” in the actor properties. They will still be picked up by screen traces though, so the GI from them will be view dependent.
I tried this but I’m still seeing a massive performance hit with Lumen GI on.
Are you using hardware raytracing or software raytracing for Lumen? Disabling affect distnace field lighting will only work in software raytracing.
Regardless, I would suggest you profile your scene so you can get a more granular look at your performance expense.
