Unerstanding GPU Lightmass

Am I correct in assuming GPULightmass is essentially a quicker way of creating your baked lightmaps using the GPU and Raytracing instead of the CPU?

If so should you disable any RayTraced GI when using it?

Yes, it’s essentially the Build Lighting option that runs on the GPU.

RTGI is for real-time global illumination, GPULightmass is not.

Too many acronyms. RTGI stands for
Real-Time GI
Ray-Traced GI?

If the latter can I assume from your answer that it is perfectly ok to use both? ie baked GPU lightmass AND RTGI?
Just seems that they more or less do the same thing and if you don’t need Real-time updating of your GI, it makes sense to disable it.

Yeah it could be confusing, but here is the RTGI definition from the UE4 documentation:

So yes, it’s raytracing and it is real-time. The confusion comes from the fact that ray tracing is a rendering algorithm used for decades in offline rendering, and now that is used in real time as well, some acronyms are misleading. In short, these days unreal uses RT for all kind of real time ray tracing (RTRT) techniques.

Thanks. How does Epic Games RTGI compare with Nvidia’s RTXGI in terms of performance and quality? After a lot of searching can’t seem to find any comparison.