Are you using the 4.21 version that was just added?
I was hoping that the new version would fix issues with the Titan V but no luck on that either. 
I managed to get another machine, performed some tests and I confirmed some issues. I’ve uploaded a new version, you can have a try
, how does lightmap resolution work differently in GPU Lightmass versus the old CPU version? I’ve noticed that doubling it does not make my render time 2x2=4 times as long; I also thought that you said that surfaces reflect more light if they have a higher resolution. Would you be able to briefly describe, I’ve been experimenting and am not totally sure what I’m seeing at different resolutions. The speed of GPU makes it easier to test, though.
If your render time is not square-proportional, your scene may be CPU-bottlenecked. You can consider send me your scene for me to investigate, since CPU perf issue is what im doin for th next version.
I will. It’s a Datasmith scene, I will clean up and message you with a Dropbox or similar link in a day or so. Thanks.
Some of the materials are Allegorithmic’s, I will have to replace those with Epic’s (don’t need a note from their lawyers…).
Yes Im using 4.21 but not working its error.,
Were there an update regarding the engine modification required for 4.21 source version to work?
Using latest 4.21 from Unreal repository i have errors on my side.
Thanks !
I’ve uploaded a 4.21.0 version in the main post, you may have a try (haven’t fully tested, just cherry-picked from my 4.21.0 branch)
Hi every one
Is there any chance to work with Stationary Sky light?
becoz I have an exterior&interior scene together and I wanna sky light photons go to the inside of my house !
EngineModification4.21.0.zip working perfectly now.
Thanks ! 
Anyone else able to repro HLOD lighting not working?
Does GPUlightmass work with lightmass portal actor?
Also does the number of sky lighting bounces have any effect?
Thanks
Could someone tell me, what I’m doing wrong? I have a single scene with an interior and exterior, mostly with Datasmith geometry and shaders, and textures resized by hand between 512-1024px res. At some point, the light build stopped even through the console. At the moment I have around 220 items in the scene for which you need to build a light. During the calculation of bounces, the memory of my GTX 1060 is loaded at about 4.9-5.2gb out of 6, but after last bounce pass, I’ve always get that “out of memory” error. Hom many VRAM do I need more for the next step? Or this is impossible to get away from that, for now? I’m using gpu lightmass for UE 4.20.3
For GPUs with low VRAM amounts, try to keep your lightmap resolutions to 512 and lower. 
Yeah, I’ve done it. For biggest parts, I’ve got 256 or even 128px, but I need to understand how many percents of free VRAM do I need after that bounce passes because if it’s not fitting into my limits, that’s kinda sad. There is not much to optimize in my scene already. And then, somehow, after all, my scene had been baked before, but the changes in it were not so many. Literally added a couple of new items. Perhaps it makes sense to combine some meshes, like these cabinets, into one, but they have so small lightmap rez already.
Oh, and If it’s possible, maybe I can swap some rendering process on another GPU? I tried setting up swarm connection with another PC, with GTX 960 4gb, but looks like it’s not taking much of processing, and it’s VRAM definitely not used, resting at 0,2gb of load
Thanks .
Now its working on my RTX card now,.
Its also possible to support 4.19 version with same rtx card?
hi what gpu do u have? can u test it rtx bake performance? any benchmark pascal(1080 ti) vs turing(2080 ti) on bake time?
just find the results on here. https://render.otoy.com/octanebench/…r=&singleGPU=1
increased cuda cores need to make a difference or?
Hlod’s turn black for me in the 4.21 version. Several pages ago already mentioned he was working on many changes regarding (h)lods. I guess he disabled those modules altogether for this temporary 4.21 version - until he’s done with those changes (4.22?).