That explains why I’m here 
I’m not a pro but could this just replace lightmass and speed up our process big time? the thing is Octane is a unbiased pathtracer. That could give much more accurate results than photon mapping. It also runs on gpu! (GPUS even)
This is a feature from the upcoming Octane Render 3
**
Advanced live texture baking**: A feature that’s most beneficial for use in real-time game engines, OctaneRender 3 supports unbiased GPU texture baking (UV or volumetric) of global illumination, spherical harmonics and 8D light fields in Unreal Engine 4 and Unity plugins.
source : https://home.otoy.com/otoy-unveils-octanerender-3-worlds-best-gpu-renderer/
I have another question about portals. I made a test scene for improving my skills about interior-exterior scenes. I use 's lightmass settings for 4.10 version.
Are portal lights useful for interor/exterior scenes? If i use them how about my exterior quality?
Portals just tell lightmass where to look for extra detail. You would just put them in the windows, just like you would with an interior scene.
Nice scene there , how long to build?
This is the first time i will build with foliage. But without foliage it took nearly 8 hours medium settings and 's lightmass settings. But i have a workstation. It is really full of power
Now it is building lights with medium settings and original baselightmass.ini file (UE 4.10 version). I will share results 1-2 hours later.
**My results: **
Scene has 109,844,565 triangles.
Static Lighting Level Scale : 0.15
Num Indirect Lighting Bounces : 20
Indirect Lighting Quality : 10
Indirect Lighting Smoothness : 1.1
Compress Lightmaps : YES
Medium Preset
UE 4.10
Render Time : 5 hours 9 minutes
My computer specs:
2 x Intel Xeon E5 2650 v3 (2,30 Ghz) (Totally 20 cores and 40 threads)
32 gb RAM
3 x SSD Raid 0
Nvdia Quadro K4000
Now i will download 4.11 preview 2 and try portals. It took one or two weeks than i will share new results.
Not sure if placebo or not but in 4.11 preview 1, I had no light leaks under walls (splotchy light shadows creeping under walls that shouldn’t be there), but now after downloading 4.11 preview 2, the same scene appears to have leaks- I did rebuild on slightly lower settings so I’ll try going higher again and report back!
My biggest wish would be to be able to import lightmass from another render package like Vray.
We can easily render to texture, and they have passes like the VrayRawLighting that would be a perfect candidate to replace lightmaps.
It would make the work between Unreal and other 3D package so much easier, letting Unreal do what he is best at, real-time view/interaction, leaving offline rendering to those who excel in that field.
I’ve already spoken with Vlado (head coder and owner of Vray) about it and he is more than happy to get this bridge happening between Unreal and Vray, just need unreal to agree with the idea.
What do you think of this @?
Vray for Unreal Engine - 
Don’t post such lucrative and heart breaking messages - it’s a felony.
Jokes aside, Light Cache and Irradiance Map can perform wonders in Unreal Engine. But again If we look at the direction of Lightmass development, it’s becoming more user friendly day by day and I am really hopeful about Real Time GI (VXGI and Enlighten) rather then Offline renders. I wish for Octane Render to become available for Unreal Engine rather then Vray.
Sorry I didn’t made myself clear.
I didn’t meant getting Vray straight into Unreal.
As I said, we can easily render to texture from any package that supports Vray (mainly 3Ds Max) and get those maps straight back in Unreal.
Therefore, something like VRayRawTotalLighting could be a good start, comping that with the diffuse filter and the reflection pass and you’re good to go.
Getting the diffuse and reflection/bump/normal/ etc is already possible, only the actual light information isn’t, because Unreal uses his proprietary lightmaps.
Lightmaps are just maps, maybe designed to work with Unreal for sure, but it would be great if Unreal implement getting lightmaps from other packages.
This would give us the possibility to export light/shadow calculation from other render engines like octane as you mentioned.
I’m sure it would take Unreal some work in the background to get it implemented (much or not?), but it’s just a decision they need to make
Otherwise they could stay with blinkers and continue to push their own implementation when other solution out there have already proven everything.
There are a million reason why Unreal doesn’t even compete to Vray for production reasons (try to render with 50 nodes only the lightmap of 1 chair or sofa in your room) and they (Unreal) will use a LOT of man power to try to re-invent the wheel when it’s just there, ready to be used.
I did understood you before but what’s you are suggesting is none other then light baking just outside the engine with mariginal quality difference as of now (as materials will still be done in unreal engine) and as any kind of texture baking requires unwrapping, it’s only good if we remove this altogether, which is the underline problem cause here.
Lightmass is evolving and I also know that it’s still way far behind from some of the major offline render engines but as embree is already introduced and things are looking to turn around. I don’t believe only calcuting lighting with offline render engine will do the job here, there are so many things that need overhaul.
And I think there are different types of wheels for different needs.
I made the same experience. A really nice and smooth rendered scene became splotchy after updating to 4.11.2. I used the same settings for both calculations just added some more furniture.
I like your grass. Did you build it on your own or is it part of any package? Or with other words: where can I get this
I’ve made some test and the light take a lot more time to build in preview 3 than preview 1 
Before lightmass portal with 4.10 version, i created my workflow for lightmass settings (mixing koola’s, rafareis and my methods) and i was starting to learn parameters effects to my scene. Everything was getting clear. But after lightmass portal i’m confused. I don’t know, i have to change baselightmass.ini file… And lightmass portals increase building times nearly 5-6 times in my scene. Should i use them for every windows? Lightmass portal is unnecessary if i have large windows? Or what about if i have non-regular windows? What will happen if i use them bigger than windows? Is there anything change will i use it inside of the windows or middle of the room? There are lots of questions like these.
I guess we need an extensive guide for lightmass portals and lightmass settings… Like experiments…
Here is my scene. I deleted landscape and foliage for shorter render times. Now my machine works on it with lightmass portal version… without lightmass portals building takes 82 minutes (with 4.11 preview 3).
By the way front side of the villa… you can see large windows of front side…
Here is non-regular windows…
Lightmass portal which is at the outside of the window…
I think you probably only need portals if there are small windows and not enough light can get in - your main room probably doesn’t need them.
@goergino
Can you tell us which settings do you have in editor and in the baselightmass.ini File?
Do you use a skylight and directional light?
Cheers
Marcel
With portals, you can get away with lower lightmass settings, and not messing with the ini as much. I would still use them for every window, and try lowering Indirect Lighting quality to speed up render times. It should be in the middle of the window, and take up the entire length of the window, and be used for every window where you want higher quality lighting and shadows inside. It should be slightly larger than the window, and can be used on big windows.
Good to know!