Why does my baked lighting have these issues?

Im creating a VR Game in UE 5.3.2 using the VR Template. I wanted to try the GPU lightmass building using the plugin for UE because the CPU was really slow. I set up the plugin as in the UE 5.3 docs and after building the lighitng looked much better than cpu and was faster.
The issue is with GPU the landscape has no lighting at all and is black, but other meshes are just fine. CPU has artifacts and in general doesnt look as good.
I also tried simply migrating the map to a new fresh VR Template project and enabling only raytracing, virtual textures and virtual texture lightmaps.
Also the landscape has no materials.
Some pictures:


Artifact when using CPU.

Black landscape when using GPU.

CPU quality.

GPU quality.

Adding a small landscape (default settings) shows artifact when using GPU.

Fine when building with CPU.

What is causing this? Both options have issues for me, so I need to solve this to continue developing.

epic’s gpu lightmass has a bug in it, that breaks lighting on landscapes. community member backported the 5.4 fix to 5.3.2.

Is it normal to have such a big quality difference between CPU and GPU? I would have though CPU would have better quality.

gpu has more math power to sample the environment. that’s probably one reason.

Looks like the GPU lighting does not have shadows on the landscape. The landscape does not cast shadows on other meshes or itsself. This isnt the case when baking using the CPU. Any idea why?

Hi @ChSt15,
Your problem is directly related to fix of my patch from the Epic GPU Lightmass which requires DX12 and SM6 enabled along with installing my backported patch
EpicGPULightMassPatch/README.md at main · jimshalo10/EpicGPULightMassPatch (github.com)

This was built to fix the problem

GPU Lightmass not working on Landscape - Development / Rendering - Epic Developer Community Forums (unrealengine.com)

Hi, thanks for the patch. Defintely solves the original issue, but is looks like the other person using your patch also has the same issue of the landscape not casting or receiving any shadows during baking, but works with dynamic lighting on the directional light.

Works great, thanks so much!!
Can’t believe such a tiny change didn’t get included in 5.3, quite frustrating.