I hope you have 56 000 cpu cores available or brace yourself!
Lol, for my scene I don’t need super quality, just don’t be full of splotches everywhere.
Screenshot of my scene before ini change:
Screenshot of my scene after:
Build lights 4 hours in a AMD fx6300.
Static Lighting Level Scale : 0.7
Num Indirect Lighting Bounces : 100
Indirect Lighting Quality : 10
Indirect Lighting Smoothness : 0.7
And in the BaseLightmass.ini :
NumHemisphereSamplesScale=100
I haven’t more screenshot of before vs after, but had splotches like that everywhere, and now is a lot more clean, for me, this balance time vs quality is ok, I know isn’t perfect, but good enough:
I have a question. If the original value was 8 in the .ini for NumHemisphereSamplesScale why the jump to 100? Did you guys try 16, 32, 64 etc. first?
I notice that, for really nice " shadows" see post for reference, check the second picture the indirect lighting smoothness needs to be around 0.4-0.7, it really depends on the scene ( I’m using bounce cards ), since that value can mess up the entire scene.
Do you use any alternative tricks to achieve those soft shadows?
So, I am wondering. What is smarter. Light your scene with only a skylight and a directional light or use the bounce card + spotlight technique? Which gives better results?
From what I’ve seen if you’re using only sunlight and skylight, in order to have proper indirect lighting inside an apartment for example, you should increase the Indirect light intensity on the light itself, but that for me seems to be the main problem with light leaks, so I usually stick with bounce cards.
The bounce card technique is used widely on Max/Maya/Vray/other renderer because it gives better results and you can control much better the indirect lighting on an area.
I also use a bit of boost on the lightmass settings to increase the overall brightness on the scene…but also using the post process Indirect lighting gives you good results ( in realtime, which is nice ).
Sounds good 
I will give it a try!
Good findings !
So, better not use fake lighting with bounce cards? Only sun and sky? I am afraid that its not enough to light a whole house only through the windows …
I personally think you put lights only where they exist in a real building. So, if lighting from windows isn’t enough add light fixtures where needed - either down lights or lamps/sconces etc.
I agree with you man. Let’s just open the **** lights haha!
I recall Modo came up with a solution to this called portals I believe. From what I remember it takes light and channels it through the window openings. Anyhow, maybe something to look at?
Hey guys, great talk on the settings. I hope I’m not too off topic, but I’ve setup a swarm render farm to help with the increased render times of these settings. It seems that the farmed jobs seem to stop/die (see gaps in screenshot) in the middle and then pick back up. Is this normal or do I have something configured wrong? Adding a bunch of additional CPUs to the farm only cuts my time by about 20%.
I was thinking about portal lights also. I render and bake a lot in mental ray and portal lights on interior openings are really necesary for clean solution in reasonable time.
quick question. I looked for the Lightmass.ini file and it seems to be in these weird locations:
Unreal Projects[name]\Saved\Config\Windows
Unreal Projects[name]\Intermediate\Config\CoalescedSourceConfigs
The file in the first location is empty so I assume it’s not the one. I changed NumHemisphereSamplesScale to 100 in the second file and I didn’t notice any difference so I’m wondering if it’s the right .ini to modify. Where is the Lightmass.ini file located?
Edit: sorry I misread the file name. BaseLightmass.ini doesn’t even exist anywhere in the project folder.
Thanks
BaseLightmass.ini is in the UE4 installation folder, it contains the default settings, the config files in your project folder are based on that and override the default.
that’s what I also have found while searching for some information. too high Indirect Light Intensity most certainly introduces leaks. you could try increasing it a bit till the point when leaks appear and then increase camera sensitivity in PostProcess volume… this helped in my scene a lot…
I’ve made my own tests. I used to rely too much on lightmap resolution to get rid of the splotches. But this time I tried to mess with the values in the ini and managed to get something better, with lower lightmaps. These renderings are not final quality but it looks decent for ‘‘untextured’’ geometry.
This thing is an unoptimized section of the Salk institute made by Evermotion. It’s 100 pieces (lol) and the walls have extruded lines, each tile of the flooring is geometry, etc. I still only used flatten mapping with steamroller and set the resolution to each mesh to 256! These would not be final render settings but it’s already not too bad for 256 Lightmaps.
Settings :
skylight with Epic courtyard hdri. intensity 8. static.
basic wall material from the started content
scale .15
bounces 100
quality 10
smoothness .66
in the baselightmass.ini I changed : (based on what suggested, but apparently he deleted his test post he made earlier…)
NumHemisphereSamplesScale=128
IndirectPhotonDensity=1200 (I doubled the default value)
IndirectIrradiancePhotonDensity=600 (I doubled the default value)
Compress lightmaps is set to false.
took 2 hours to build.
Don’t understand why deleted his post, that was good information!
@: despite being 256 resolution the lighting looks pretty good!
This evening I’ll test some scenes with those settings and check if the results are much better then what I got, hopefully spending less time while rendering 
Sorry guys, I’m just planning a final guide for this topic. There is a lot of disconnected informations here.