Noob question about BaseLightmass.ini

Hello guys ,
After i downloaded Koola’s scene … i noticed when i re-build the lights that i get lower quality results than the original state of the file .
So i assume that has something to do with his playing around with the BaseLightmass.ini …
so my question is he referring to BaseLightmass.ini the in the install folder ?? for instance on my computer it’s here >> C:\Program Files\Epic Games\4.6\Engine\Config
or does each project and level has its own ini file ?!
also i found 2 files called Lightmass.ini ( without the word “Base” ) in my project sub-folders here :
H:\Unreal\ArchViz\Saved\Config\CleanSourceConfigs ( this one has the same data and values like the BaseLightmass.ini in the install folder )
H:\Unreal\ArchViz\Saved\Config\Windows ( this one is empty )
So which ones affect the actual results …
Thank you in advance .

Hey, Rotab3D,
The BaseLightmass.ini from the install directory is the one that changes light build settings for all your projects, and is the one that Koola modified. I don’t know if there is a way to do it on a per-project basis. However, I have seen a lot of Unreal staff warn against modifying the lightmass config file, because it is unnecessary. It is only meant for programmers who have very specific reasons to change it. The secret (as far as I’ve learned) is that most of those settings are actually available to you behind-the-scenes in the editor. When looking at the scene that Koola published, it looks like he left most of the editor settings at their default and went straight to the .ini (unless my local copy got changed), when he could have achieved the same results by editing the Lightmass settings inside the World Settings window.

By setting the Static Lighting Level Scale to something less than 1, like .95, you can increase lighting samples.
By setting the Indirect Lighting Quality to 6.0, all those random .ini settings that you want to tweak will automatically be cranked up.
By setting Indirect Lighting Smoothness to .75 with that high indirect quality will give crisper and more accurate shadows.
Have the Indirect Lighting Bounces set to 100 like Koola, although this is more of a placebo effect since nothing past 4 or 5 is significant.

I haven’t tested this myself, so correct me if I’m wrong. Having the editor settings cranked all the way up like this should achieve any lighting quality that a noob or experienced person would be able to get out of modifying engine settings that they don’t truly understand. Hope this helped!

Wow I totally agree with u bro. After my extensive R&D I have figured out the same as you said here.
Thumbs up for Ur generous effort for making it clear about the settings.
U are absolutely right what u said here.

Thank you StephaBon , This was really clear and helpful explanation , :slight_smile:

Ok very helpful on the lighting settings, but what about the meshes im using? What is needs to be done to get them looking good?

The whole G.I method Koola used is outdated anyway. Now we have lightmass portals so tweaking the .ini isn’t as relevant imo. You should be able to bake a higher quality version of his scene just by tweaking the in-editor settings like stephabon suggested. IIRC Koola used small lightmaps too. Don’t be afraid to increase their resolution.

I’d really love it if the Koola scene was updated or replaced with a scene using portals. At this point it is very dated and gives people a lot of miss information when they are using it as reference to how to make an arch viz scene in UE4.

Hi !

I did some updates on the scene to use the latest lighting features.
This time I use the skylight portals and I don’t tweak the lightmass.ini.

I hope the update on the marketplace will be quick.



Wow I’m amazed that you actually did it, and how quickly you updated it! Looks great.

Good job Koola! Looks awesome now.

thanks @koola! always a great help learn from an example like this!

Any status on your update @koola ? Your scene in my launcher is still the old one afaik.

The update is now available.

Hey Koola, thanks a lot for updating this. I was just having a quick look and notice that you are no longer using bounce cards in the scene. In your opinion are these now unnecessary with using portals?

Yes, you no longer need to tweak lightmass.ini or use bounce cards since they added light portals in 4.11. Most of the Lets make Lightmass EPIC (and understandable) thread discusses this.

that is why when i download koola Lightroom scene i didn’t see any bounce cards spotlight in the editor except lightportal on all windows and opening. i keep searching on that quad, i guess im late on this. thank you so much koola.

I use UE4 form 2 weeks and I made some test and I think that in most cases BaseLightmass.ini tweaking is better that this what Epic gives out-of-the-box.
It is because of render time.
Lightmass tweak I got from:

These are 3 images rendered with the same in-editor setup ( network machines: i7-4771 + i7-4770 + 2xXEON5650 ) :

0 - Preview mode with BaseLightmass.ini changed - build time 1.5 min ! ( just indirect shadows little to dark and sometimes light artefacts can appear in very close-ups /tested on Evermotion ArchInterior vol3 scene 1 that I got in 1h instead 10h/ - depends on lightmaps and scene complexity - but overall look is GOOD )
Lightmass changes:

1 - Medium mode with standard 4.16.1 lightmass config - build time 5 min ( but shadows are poor )

2 - High mode with standard 4.16.1 lightmass config - build time 15 min :frowning:


0 - Preview mode with BaseLightmass.ini changed

1 - Medium mode with standard 4.16.1 lightmass config

2 - High mode with standard 4.16.1 lightmass config

What do you think ?

And this is finished bedroom.
With modified BaseLightmap config in Preview mode render took 380sec ( with equipment that I mentioned above ).
This is Preview mode and everything looks FINE ! Maps resolutions: 512 for large and complex objects and 256 for medium complex objects and 128 for small objects.
I use some assets. They made very nice materials workflow and fantastic BP_STUDIO blueprint for lighting ( ie. you can use typical equirectangular HDRI map for a sky light - just remember to use NoMipmaps option for HDRI image to have full resolution)

UE4 is fantastic!