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Volume samples can't be used in a multi-level setup

The project I’m working on consists of several buildings, each in their own map. They’re all loaded as streaming levels into a persistent level. For lightmass, I bake each building separately by removing all but one sublevel. I don’t hide the other levels, because baking one level with other levels hidden breaks the lighting on instanced foliage on the hidden levels.

This all works fine, except that volume samples are only kept for last baked building. I imagine that the volume samples are stored in the persistent level, instead of a per-level basis. This is rather unfortunate though, and I can imagine many others having the same problem. Is there a way around this, am I doing something wrong?

It’s a known limitation. If you need to work with multiple levels, you need to stick with the Indirect Lighting Cache. Go to world settings and change the Volumetric Lighting Method to VLM Sparse Volume Lighting Samples.

Oh, too bad! Thanks.

I have a large world with multiple levels. I have to bake each level inside a unique persistent level that is only used for light-baking. These “bakelevels” also contains the surrounding levels (to get rid of light map seams), but these are excluded from baking lightmaps in the level panel. It seems to be working mostly, but there are some issues with the volumetric lighting when going between areas.

Are these issues impossible to fix while sticking to Volumetric Lightmaps?

An interesting feature that has been added in a recent version is the ability to create different lighting scenario levels Precomputed Lighting Scenarios https://docs.unrealengine.com/en-us/Engine/Rendering/LightingAndShadows/PrecomputedLightingScenarios

It’s on my list of things to look at but from what I understand one can set up a unique level creating different set ups for the same level, along with required lightmaps.

Personally I’ve gotten into the habit of making a master lighting level with unique lighting requirements held in the sub level.