Surface cache for ISM/HISM without Nanite meshes isn’t supported currently, but should work with Nanite meshes or when using HWRT highest settings which bypass surface cache entirely
Do you mean “RayTracingQualitySwitchReplace”? This one is implemented in UE5-Main, but is mostly intended for optimizations. Using it for artistic tweaks has the same issues as tweaking IndirectLightingIntensity. Namely it can’t affect screen space rays. This means that any harsh differences between “GI material” and what’s on screen will cause view dependent GI, and lighting will shift as you move your camera around.
Unfortunately Landscape isn’t currently supported :/. You could make a temporary hack by placing some meshes under the landscape so Lumen can pick them up.
Yes, this is a pretty important topic for us.
Regarding various quality issues:
- Reflections are bad - at the moment only Hardware Ray Tracing can deliver great looking mirror reflections
- Lumen looks bad - most likely it’s caused by using software ray tracing with large (non modular) meshes. Please try checking how the scene looks like in distance field and Lumen scene visualization to figure out which objects may cause it and are not correctly represented. Lumen Technical Details in Unreal Engine | Unreal Engine 5.0 Documentation
No promises, but if anyone shares a small project with issues I’ll try to investigate what’s happening there.