Apologies if this has been brought up before but I’m having a small issue with indirect lighting - the CPU baker managed to scatter the lights around fairly nicely but using this I have ceilings coming out mega dark. I’ve tried browsing the thread for a result but it’s like searching for a needle.
Can anyone lend a hand please?
I fixed that with a higher Skylight intensity, and a few up lights (usually rectangular, at an intensity of 4 to 8).
So I shouldn’t be relying on the bounce light to produce the same effect? Using fill lights etc?
I had this issue several times. I noticed that with a specific settings sometimes the lights (spotligts in my case) stopped having any GI at all.
It happen when I changed my lights to unitless or I unchecked the use inverse square fallof. It also happed often when my light was a part of another blueprint. Sometimes when I was changing the source radius. The thing is that it sometimes worked and sometimes not. My workaround is that I always place my lights directly in the world and not as a part of a blueprint, I always use physical units with inverse square fallof and since then the lighting always bakes nicely. Hope it helps.
Does anobody compared new 2080ti with old 1080ti? What is about performance in GPU Lightmass calculation?
ZacD, did you have 1080 ti before?
someone to help me? my new graphic card gtx2080ti appears a error with the gpu lightmass, i already clean and validate the swarm agent… im trying with 4.20.3, nvidia 417.78 driver
When you have a look at Game Benchmarks, the 2080Ti is between 20% and 30% faster than the 1080Ti, so i guess this is what you will get for your calculation boost in GPU lightmass, plus more VRAM to use. Beside that, im kinda sure that the RTX “part” of the card wont have any influance on GPU lightmass caluclation speed.
That’d comparison with Game Benchmarks would be ok for in-game performance with Ray Tracing disabled… For GPU Lightmass this could be a game changer (hipothetically). In offline rendering, which resembles much more to the process GPU lightmass is doing, for F-Storm (offline GPU renderer) a single RTX 2080 (not TI) compares to 2 x 1080TI in SLI. That is without any special modifications to the GPU Renderer code (per the devs own statements).
There is the same amount of VRAM, but 2080ti uses GDDR6 in compare to GDDR5X in 1080ti. But I am pretty sure it will not influence on lightmass calculation too much.
For now GPU Lightmass doesn’t use RTX cores, so CUDA only.
hello everybody, 
First thank you LUOS for your work
Sorry for my bad english
i was working with CPU and now i want to try GPU solution but when i want install the Lightmassconfiguration-Master
i have this message: “Unreal Engine version 4.21 not installed or registery not set” you can see it on the image.
I have found on the forum, people who have this problem on page 33 and 53 but cant find the answer
i think the problem is the registery because my ue4 isnt on my “C” disk i suppose…
Someone can help me Please :D:rolleyes:
The script is a helper to avoid manually copying, backing up, and doing boring stuff, it looks for the registry key that should be there if you installed properly UE4. The issue is definetly not related to using something else than C, is I currently use “D” and that’s why it looks the registry for the folder. I can’t however debug all situations, nor look at other OS Languages.
You can try reinstalling UE4, that worked for some people, but then egain, if it is not working you can do it manually as instructed in the first post.
There is not much I can do unless someone with the problem like you is willing to debug the issue with the registry and work out a solution. I can’t fix what’s not broken.
That’s what worked for me. The bounce light seems to work differently with GPU Lightmass, Luo would have to explain the technical reasons.
Thank you for your reply
I will try this soon, but after buy 1To ssd because anymore memory on my C disk. Hope it works 
And without your script how do you change the build settings ( production, high…) on the previous version we had to change the folder in the engine but with the GPU 4.21 unified setting i dont know. it work with the unreal build settings?
Thanks again…
You need to modify baseLightmap.ini
Scroll down to the end and find DevOptions.GPULightmass.
FastPreview:
NumPrimaryGISamples=16
NumSecondaryGISamples=8
MediumQuality:
NumPrimaryGISamples=32
NumSecondaryGISamples=16
UltraHigh:
NumPrimaryGISamples=64
NumSecondaryGISamples=16
Extreme:
NumPrimaryGISamples=128
NumSecondaryGISamples=32
“A better way is to create a DefaultLightmass.ini under your project’s Config folder which only contains the DevOptions.GPULightmass section so that you can have per-project settings.”
I guess the minimum system requirement has been changed. GPULightmassIntegration-4.20.2-UnifiedSettings.zip works on Custom Source UE4.21.2 with GTX 660 Cuda 3.0 but, it doesn’t work with GPULightmassIntegration-4.21.0-UnifiedSettings.zip, because GPU Lightmass doesn’t support Cuda 3.0 anymore. Am I right on this?
I have a GTX 970 on my other pc. But I just want to know the fact. GPU Lightmass is very nice to have, I don’t understand why that much tricky? Thanks.
Anyone how to fix this??
Trying the 4.20.1 version and hit another error, any ideas?
<None> === Lightmass crashed: ===Unhandled Exception: 0x80000003
Fatal error: [File:C:\UE4-GPULightmassIntegration\Engine\Source\Programs\UnrealLightmass\Private\Lighting\LightingSystem.cpp] [Line: 1402]
Static lighting thread exception:
Unhandled Exception: 0x80000003
0x00007ff9876edf71 GPULightmassKernel.dll!UnknownFunction ]
0x00007ff9875f59a1 GPULightmassKernel.dll!UnknownFunction ]
0x00007ff9875f7e01 GPULightmassKernel.dll!UnknownFunction ]
0x00007ff9875ee231 GPULightmassKernel.dll!UnknownFunction ]
0x00007ff9875eafcc GPULightmassKernel.dll!UnknownFunction ]
0x00007ff7afa0bf6c UnrealLightmass.exe!UnknownFunction ]
0x00007ff7afa2fb05 UnrealLightmass.exe!UnknownFunction ]
0x00007ff7afa2e849 UnrealLightmass.exe!UnknownFunction ]
0x00007ff9864e8d38 UnrealLightmass-Core.dll!UnknownFunction ]
0x00007ff9864e36d7 UnrealLightmass-Core.dll!UnknownFunction ]
0x00007ffa15e13034 KERNEL32.DLL!UnknownFunction ]
0x00007ffa16223691 ntdll.dll!UnknownFunction ]
I have also hit an assertion fail, however at a different location to leoletsrock.
We have had this working in a few scenes with promising results (UE4.21.2), but we just tried another scene (the only difference is that it is fully indoors) and we get consistent error:
Which is followed by:
If i can track down the cause of this ill report back
Hey Guys,
I just do-again all steps on page1 and things seem work perfectly fine. Here is the scene FYI. Even the strange lighting (‘‘Wave’’ shadow) on wall is magically gone!!
you are the best!
Could I get a link to the first post, same issue with registry here 
I want to fix, your script is super helpful.