We use UE 5.8.2, DX12, Voxel Plugin terrain, Lumen GI/reflections with HWRT, and VSM.
Lumen async compute uses engine defaults. IndirectCapsuleShadows costs approximately 0.43 ms in our Epic-quality RTX 4090 captures. Setting r.CapsuleIndirectShadows=0 removes the pass. We found no visible ON/OFF difference outdoors or in caves, even where its debug mask shows strong occlusion. Our runtime inventory found only Voxel terrain DF casters; skeletal capsule shadows were disabled, matching Unreal’s component defaults. Also Nanite Foliage ISKM default to off. Source inspection suggests the pass applies before the final async Lumen lighting composite, therefor Voxel terrain Df casters have no impact on the final image.
We never set r.Lumen.AsyncCompute or r.Lumen.DiffuseIndirect.AsyncCompute to 0 deliberately.
Is this expected, and is disabling this CVar project-wide safe, or are we running the risk of other features breaking because of it? Are there hardware, quality settings, or lighting paths where we would lose meaningful shadowing?
Normally, the indirect capsule shadows pass only runs when there are IndirectShadowPrimitives and that’s usually for characters and it’s opt-in (bCastCapsuleIndirectShadow), and it sounds like the Voxel terrain primitives return true for CastsDynamicIndirectShadow() so the pass is activated. I recommend working with voxel plugin dev to determine if this is necessary so you can use capsule shadows later if you change your mind, but otherwise, if you are not using the feature it should be fine to set r.CapsuleIndirectShadows=0.
does that mean if we turn it off on every primitive (in this case the voxel world), the pass would not run and we should see the same performance gain as with setting r.CapsuleIndirectShadows=0 ?
Yes, you should see almost the same performance gain as with r.CapsuleIndirectShadows=0, the only difference should be that with r.CapsuleIndirectShadows=1 you will still have some CPU work where it checks the the empty caster list and also for scene changes, but that should be negligible.
hello [mention removed], thanks for the quick reply!
does that mean if we turn it off on every primitive (in this case the voxel world), the pass would not run and we should see the same performance gain as with setting r.CapsuleIndirectShadows=0 ?