https://forums.unrealengine.com/development-discussion/rendering/1460002--s-gpulightmass/page90
I’ve uploaded GPULightmassKernel.lib in the same dropbox share. You would obviously need to add the path to wherever you save it to the build settings for UnrealLightmass in VS.
in my case the gpu is malfunctioning.
how to switch back to cpu?
If you didn’t backup the replaced files, select “verify” in the engine’s drop down menu and it should restore the original files (cpu).
See picture
This is so good - the results are consistently gorgeous and so much better than “irradiance mapping”.
I know it’s been asked before, back in 2018 - but are IES and area lights on the roadmap for support?
@KM3d300 It’s not on development anymore. was hired by Epic and is now working on a GPU Lightmass version for the engine. He was starting a new version of it already with support for new stuff and improved lightmapping, specially on UV seams. So I believe that’ll all be included in the Engine. But how long from now? No idea.
Ah, thanks @
Came to the party quite late so thanks for the update.
hello,
I am working in a project for this last months in ue 4.22…till now it was everything perfect, but since I am trying to do the last lightmass build I am having some problems…the configuration is the same as in previous builds, I am working with the “Extreme settings” and the problem is that suddenly, the build times increased a lot…the same scenen that it took almost 6 hours, now is taking 2 days…as I said, nothing new in the scene, exactly the same…any ideas? thank you very much!
When that happened to me I figured later it was a driver *issue *(there’s also something bout it on this thread). NVidia drivers will prioritize any 3D work over CUDA processing. So minimize Unreal while building, if your browser uses hardware acceleration minimize it too or turn that off and, in my case, I have to close Wallpaper Engine too. ***Anything ***that might be using the GPU for graphics processing, shut it down or minimize it. I saw an instant speed difference after closing/minimizing those while GPU Lightmass does its thing.
Hi there, quick question. Where do you modify quality settings? I understood that it ignores the settings in the editor UI. Is modifying NumPrimaryGISamples and NumSecondaryGISamples in the ini enough?
Yes, already noticed that, and these last builds the browser was closed and the Unreal editor minimized…so there was nothing going on in my computer appart from the build light…the funny thing is that the ventilator of the GPU is almost not working when baking that level, wich means the calculation goes slower as normal during those bake lights…but if I bake anything other, like the same level with just a part of the whole project, the ventilator is working full and the velocity of bake is back to normal, also in the build statics when it goes slower it says “overall xxx seconds 10.72Mrays/s” and in other cases can go up to 277,76 or 340,22 Mrays/s, so I guess that is something more objective than the ventilator 
…not sure why all this happen
EDIT: after 7hours of waiting, only got 10% done at an “overall 22332.44s 16.33Mrays/s” and still 47h to go, but it looks like the most it does the slower it gets… the GPU is almost not working, resource monitor says it is at 5% (CUDA 0-100%)…the Memory at 60% and the CPU at 21%
It looks like performance is down and I do not know why…ANY HELP?
I have just updated the binaries after identified the problem.
Packaging should now be working correctly.
You would need to download the updated binaries from the same link as before, and apply them.
Let me know if the problem is still present after updating. Otherwise, send thanks to !
I am not an expert, but did you use the script to install?
If you did, there you can find the “lightmassconfiguration.bat” where you can change quality settings
the only thing that does not ignore is: “Lightmass parameters and quality settings specified in the editor are ignored except for **Num Indirect Lighting Bounces” … **quoted from https://forums.unrealengine.com/deve…ss#post1460002
No I just copied the files. I tried using NumPrimaryGISamples=256, but I think it’s a little bit over the top, took like 25 min. Now trying 128, seems it will take about 5 mins only.
edit: yep, seems 128 is the right number 
And it looks good! but it looks slightly different than the normal lightmass, like less smooth.
with the “extreme settings” that I am working, on the ini says:
NumPrimaryGISamples=128
NumSecondaryGISamples=32
I have also changed the fireflyclamp to 10, the only number that gives me no bright splotches
Thanks. I used 128,64,1000 and it was pretty fast. I didn’t notice any splotches, but the shadows look more “hard” with the GPU version.
For example, there are the same view baked with CPU and with GPU. I like more how the shadows look in the CPU version.
Is there some parameter to make GPU shadows more soft?
GPU Lightmass
CPU Lightmass
sorry, no idea…did you use **Num Indirect Lighting **bounces = 100 ??
or maybe changing the HDRI if you are using one, I would not expect same results in two different ways of calculating light…just talking for the experience with vray cpu and gpu that have also a lot of differences…but it is just a guess
Messing up with meshs using Datasmith Mesh Editing will make it crash.
If you use high values of intensity on lights(like thousands) will make it crash as so.
He everyone!
I’m using Version 4.23 ( and build with GPULightmass 4.23), the quality is good but the build time is very slow.
When building a project, the GPU doesn’t work as well as the CPU a little.
And I want to ask you here, is everything okay is this form? or is there something wrong with me?
Please help me how to improve this.
Thanks
Change “Copy” to “Cuda” in dispetcher and u’ll see full load