^ I actually feel much better with the GPU screenshot. The CPU screen feels otherworldly. The blue hues in the GPU shot feel much more grounded in reality.
it seems like the GPU version took more influence from the skylight.
Im not an expert, so idk what’s more correct.
That’s the whole point. For or realistic scenes you might want to have that effect that GPULightmass provides, however, for games (that need to be otherworldly) you want that otherworldly feel that CPULightmass provides (but I’d love to get that feel using GPULightmass and short lighting build times 
)
There’s no otherworldly feel, that’s just bias 
Seriously though. I have a lot of experience from almost a decade spent being CG generalist (doing offline graphics). Even in offline graphics, people were using some really bad workflows up until not that long ago, and they also often excused them by artistic choice, attributing some artistic qualities to certain errors in light transport accuracy. But I don’t know of a single person who actually learned physically based workflow, and then wanted to go back to the previous workflows to achieve that old aesthetic caused by inaccurate, biased lighting.
The point here is that in both cases you can achieve very similar aesthetic, just at a different point in a workflow. If you want to have darker, more contrasty interior, you don’t do that by messing with light transport, but you can achieve more or less same result with messing with post process settings, reducing the brightness of the scene and increasing contrast. But unlike achieving that by breaking the light transport, if you do it the correct way, you will still preserve the relation of light, so the version where you have achieved it through post process will always look better to human eye.
Problem here is that in UE4, both CPU and GPU lightmass have some issues with the accuracy, but that’s to be expected given the usage for realtime graphics, so often one doesn’t have a choice. But if you do, always choose the more accurate way, if the performance is similar.
That being said, looking at the renders above, CPU vs GPU lightmass, it actually confirms my point. The CPU version here does clearly a lot less clamping of the sun light bounce transferred from the floor to the ceiling. It’s actually more physically accurate compared to the GPU lightmass one, which clamps way too much. Clamping in this context is a method to prevent fireflies caused by high contrast areas, you can find out more here: https://forums.unrealengine.com/development-discussion/rendering/1460002--s-gpulightmass/page10 . It was actually me who recommended it, but clearly, GPU lightmass seems to use it way too agressively. Non the less, the one you’ve considered better looking is also the more accurate one
@**BoothStudios **To investigate, lets tune up FireflyClampingThreshold in BaseLightmass.ini to some value like 10000.0 and see whats happening
How is new version of GPULightmass coming along? :o
Urgent question: Can I install GPU files from 4.21 to 4.21.2?
Not making much progress - ray tracing features in 4.22 is eating up a lot of my energy
No problem with subversions of the engine, go ahead
Any chance ray tracing is for official lightmaps baking solution in 4.22 ?
It is simple amazing tool. I was calculating a day the interior scene by standart unreal CPU lightcache, after 12 hours I have stopped it and tried your GPU solution. The result was done in 1 hour and result…fantastic! Only one minus is my geforce with 6GB Vram, so I can’t to use much 4096 px texture sizes. I run own BAT file to save as much Vram as possible.
Pleas keep in development of this super awesome stuff. Thank you for your work!
Btw my scene took 64 GB ram, I think there is something wrong with memory optimization, anyway it worked and don’t know if this was caused by Unreal direct shadows or GPU process.
Hi, a problem with double sided material affecting bounced light, does it apply also to double sided mesh geometry?
HI,
after update to 4.22 I have following message
I had Lightmass set to GPU when update arrived.
can you advice what to do to make it work?
is the script creator. Maybe he can help you.
My advice is just download GPULightmass and unzip it yourself in the engine folder.
But if you really meant 4.22, I don’t think it works with that version yet.
good day
is there binary installation for 4.20.3?
Hi @
Sorry my mistake, 4.21.2.
Yes script gives an error.
UPDATE:
manual instalation works fine with 4.21.2
Yes if you could be so kind and update your great script - it is so convenient
thank you.
It means the script does not recognize the Lightmass.exe hash and cannot decide which version to use. That also means the lightmass core changed, and would probably also mean that GPU Lightmass may need to be updated for 4.21.2 in order to have the latest changes included (not sure what changed thou).
To work around it, I’ll need to update the hash table to the latest version. There is a script in the “Hash” folder just for that called “HashCheck.bat”.
I’m currently on another project, but I’ll see if I can make some time this week to update it.
can i get GPULightmass installation for 4.20.3
The 4.20.2 version probably works just fine. Pretty sure I used that on 4.20.3 myself.
thank you for the prompt respond
I can test that today but I updated to latest version of 4.21 and need to reinstall GPULightmass as it no longer works.