Emissive material boost for lumen

Hey everyone,
I wanted to have really bright windows by setting the power of emissive material to a high number (say 50) but that causes lumen to scatter light from it everywhere (especially on exponential height fog)!

While I can completely remove it by disabling “Dynamic indirect lighting” on that object, that’s not what I want, I just want to reduce the effect like “emissive boost” in lightmass settings.

Is there any setting that I’m missing?

Someone can correct me if im wrong but I believe there’s a lumen console command that boosts the GI globally for all emissive materials but doesn’t make them contribute more to the volumetric fog which sounds like exactly what you’re after.

Just go through all the commands with lumen in them or scour the documentation on it

Try This: How to Create Masks With the Custom Depth Buffer | Tips & Tricks | Unreal Engine - YouTube

Material nodes:

Added the multiply node for the emissive intensity. You won’t get any type of lighting from it, not even SSGI. the fog will not be affected either.


Also works great when behind objects:

If performance is not your concern and want light to affect the immediate area, add a light in front of every window.

Hope it helps.


Heeey, I’m going to try and find this console command(s) you’re talking about, any clues before I spend the afternoon trying them all. Much appreciated.

Hi there, this might be a stupid question but can someone confirm that the “Emissive boost” setting (in the material instance details panel and/or the object details panel) DOES work as expected for you in UE5 / Lumen? I’m unable to get that setting to have any effect and I can’t figure out why. I have an emissive material on a plane (a glowy cyan pool of water) and I can set its emissive boost to 1 or 100 or 0, with no apparent change in the amount of emissive lighting on nearby objects.

As far as I know, it’s only for static baking since it’s under the tab of “lightmass setting”

Ahh got it. I’m new to Unreal and I get pretty confused with which lighting-related settings are vs. aren’t applicable in a fully-Lumen scene, but it helps to know that “lightmass” related settings are only for static baked lighting. Thanks!

Hi, first of all, thank you for this tips.
secondly, I’m having trouble to have it mask out different color emissive in the scene. I’ve created multiple custom depth material instance, and plug it into PostProcess but seems like it can only mask out 1.
any idea? or it is the limitation?
thank you.