Has this overhaul happened in the past few months? I can’t find any further mentions. The potential improvements are staggeringly awesome!
Prometheus - GPU Lightmass Overhaul
Lightmap UV Testing
4.22.0 Release: 4.22.0-Release - Orangedox
Updated 13:55 2019/3/17 0.0.1: Fixed some bright corner issues (lol).]
Updated 00:10 2019/3/21 0.0.4: Fixed chart dilation issue.]
Updated 13:11 2019/3/28 0.2.0: Greatly improve video memory consumption.]
Updated 14:35 2019/4/04 0.3.0: Added skylight importance sampling and other parameters.]
Needs CUDA driver version >= 419.17
Since the overhaul took much longer than I expected, I decided to roll out some new versions containing important functionalities to test whether they work well and if I should invest more into them. This version focuses on lightmap UVs and dark corner elimination.
Only a single static skylight is supported, no other lights. Also no masked material support, no VLM/SPLS support. Just testing lightmap UVs.
Creating lightmap UVs for complex objects & dark corners at object intersections are concerning/frustrating issues always. I have been testing multiple (potentially costly) techniques to see whether I can mitigate most of the artifacts - especially at lower lightmap resolution. Now this version should be able to get rid of most of those ‘common’ dark corners, provided that **the hard edges on your object are properly split - which most auto UV gen software would do **(Due to limitations in UE4’s lightmap directionality representation, ‘spherical harmonics’, non-planar texels won’t work well even if Prometheus has computed them super precisely, which means lightmap texels crossing a hard edge will never be correct).
Baked with Prometheus:
V-Ray viewport reference (Reinhard tonemapping, exposure +3)
What about Build lighting from command line - Rendering - Epic Developer Community Forums ? … says can’t be absolute path … not to include “folders”
me too, I have this problem and i can not fix this, can you help me,please
Thanks, I will test this version of GPU Lightmass ASAP and compare results to the past versions.
Hey ! Got this error on a clean engine with Prometheus 0.0.1, any idea what could be the cause of it ? Looks like a dll mismatch.
https://i.imgur.com/eHGZQkE.png
I’ve updated a fresh packaged version, you can try again
Good now, thanks for the quick patch ! Looking forward to a day of testing tomorrow 
This is amazing. you are awesome. It is possible that in the future this will work for AMD, I was thinking about buying a vega 7
Hi ****,
I am testing your new Prometheus and getting some problems. On the first pic white dots, and on the second dot it is too noisy (how can I switch settings to max quality?)
I found this lines in code :
[DevOptions.GPULightmass]
NumPrimaryGISamples=32
NumSecondaryGISamples=16
FireflyClampingThreshold=10.0
Which numbers I need for Ultimate settings like in previous ver. of GPU Lightmass ?
Prometheus currently does not respect num samples settings :(. Its main purpose is to test dark corner elimination and UV robustness. Did you get problems from them?
Yep, just tried 128/32, nothings changed. No I didn’t investigate for dark corner elimination and UV problems yet, but I’ll do it. Now I know that this version is just for testing, so I will ignore all this artifacts… Thank you.
Any ETA for final release?
Does it work with old GPUs (GTX670)? I try to use it with 4.22.1 and I run into “invalid device symbol” error then crash. I used the automatic installer. (Sorry if that was asked before)
Same here with GTX 650.
Are multiple GPUs supported?
Also, is it possible to use different GPUs, like none SLI setups, for example a bunch of 1060, since the heavy process is on the memory this can probably improve times keeping the scaling costs low.
I got the following results. Sketchup to 4.21 via Datasmith. Upgrade project to 4.22 preview 5. Bake with Prometheus. Thoughts?
Hi to all,
First of all thank you for this trick.
I am having the issue of very low performance of de GPU running at 5-6%.
Graphic card: 1060 6gb, drivers updated.
Anyone know how to improve it?
Thank you in advance.
The card needs to support SM 3.5, which means at least 7XX series
No multi GPU support currently 
If you’re on Win10, select this queue type and see whether it is fully utilized:
Starting from NVIDIA 419.xx drivers, how the CUDA and 3D queue are scheduled is changed and 3D will always take priority over CUDA.
Looks no problem to me Are you having any issue with complex objects? One thing I want to achieve with Prometheus is that it should work with auto gen UVs (not generated by UE4Editor, but by your modeling software, like ‘auto projection/layout’ in Maya) without producing artifacts beyond UV seams (which is supposed to be addressed in following releases) so that lightmap UV workflow can be simplified greatly.
I’m good with it :). I will try something more complex (irregular sculpture perhaps) this weekend and report back. Thank you for your continued work on this!