Volumetric Lightmaps and Levels

Development Rendering
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Dear all, I’m having a really hard time finding solutions/answers to what I’m facing.
I have a fairly big world in UE4.27, with two major buildings on it. These buildings are in their own sublevels, so I can build lighting for them separately.

The main issue comes when I build the lighting for building 1 first, then I build lighting for building 2, the volumetric lightmap data calculated for building 1 is gone, only building 2 will have it correctly.

Is there a workflow where I get the correct volumetric lightmaps for my whole world, but I don’t have to bake everything at once? Obviously, my main reason for baking the levels separately is due to VRAM limitations and time-saving.

I would really appreciate any input. Thanks a lot in advance.

1 Like
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Composition of static lighting data (including lightmaps, VLM, precomputed visibility etc.) from different sublevels has never been supported in the engine - it is expected that you build all your sublevels together. Some people are lucky to get it working, occasionally.

That being said, there’s indeed some experiments going on with VLM composition, due to the need of supporting large worlds.

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Thanks for your response, so how is light baked for large worlds? I also wonder if theres a way to only build volumetric lightmaps and not static mesh lightmaps?

Edit: I think I will experiment with lighting scenarios, perhaps having one for each sublevel that I want to bake separately.

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You can set static meshes to only use volumetric light maps. Gears 5 apparently used this approach.

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Thanks for the tips everyone, I actually managed to fix these issues with lighting scenarios. As you enter a building you need to load its specifi scenario, then you unload it when leaving.