Lightmass Importance Volumes

Would it be more beneficial to have multiple small lightmass volumes versus one big one to cover the whole level? I am having issues when I rebuild lighting that is starting to confuse me. Light in rooms where there are no lights or windows to give light. I have a Sky Sphere in the level using a Directional Light as the sunlight control for direction of the sun. I am also using a SkyLight to help eliminate some of the shadows in the darker areas so that things look like they would in the real world when a shadow is behind a tree you can still see what is behind it just not as bright as everything around it. Room that should be having light in them via a window don’t have light at all. When a light comes in a window it should illuminate that part yes but it should also give a bit of light to the room since it is a light source.


The first image is in the editor and as you can see there are no light nodes anywhere in there. The second image is when I am actually in game and as you can see there are no lighting resolve issues that need address as I rebuild light every play it feels like. THere should be little to no light in this room especially in the back near the pillars. Am I missing something here with Directional lights and Sky Lights? Or is it because of the single LIghtmass Importance Volume.

Is your skylight set to static?

It was set to stationary. Set it to static and rebuilt lightning, and that did the trick. Thank you for pointing that out.

You can have as many small ones as you want, but it’ll make no difference. At build time, Unreal will just make a single large one that encapsulates them all regardless. The end result is the same, just use a larger single volume and save yourself the trouble.

I’m gathering information about this topic. It sounds like multiple smaller ones would still be beneficial?

From the docs:…ghtmass/Basics

“If you place multiple Lightmass Importance Volumes, most of the lighting work will be done with a bounding box that contains all of them. However, Volume Lighting Samples are only placed inside the smaller volumes.”