Lighting bleed problem in the large scene

I am trying to build the large scene with 20 identical rooms.

(1) *Room contains one stationary spotlight with
intensity: 0.5, inner cone :90, outer cone: 90, and attenuation radius: 1800.

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(2) Level has stationary directional light with
intensity: 3.0, indirect lightning intensity: 1.0, volumetric scattering intensity : 1.0.

(3) Stationary Skylight with
indirect lightning intensity: 1.0, volumetric scattering intensity : 1.0.

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(4) LightmassCharacterIndirectDetailVolume, LightmassImportanceVolume and PostProcessVolume. Here is the light mass settings
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After the building the lighting i got these results.

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There is the lighting bleed in the corner as well as at the intersection of the walls.

(5) Here are the lightmass density sceenshots.
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It’s working with 4 Rooms. But Unable to work with 20 or more rooms.

I also tried to build the scene with UE 4.14 and UE 4.17. I got the similar results.

You could try putting large boxes between the rooms to help stop leaking.

Make sure that your walls and floors do not extend beyond each other otherwise light or shadow can bleed onto visible areas. If you don’t have an outer wall then having an outer surface for each room helps as well.

Is there a reason why the rooms are so far apart from each other? You have a lot of space between them. So the light mass importance volume has to be larger than it needs to be. You could save render time and decrease file size when you put them closer together.

Something about stationary lights: they have by default a dynamic shadow distance of 0.0. That makes them a static light. Have you set the dynamic shadow distance to a higher value? I think max recommended is 2000 = 20m but I would set the main to something like 600 or you will get really visible changes between the shadow cascades.

The 2nd spot light inside the room should probably be a point light and also probably doesn’t need to be stationary (part dynamic). Unless you want the dynamic shadow from it.

It would be good to know what you actually want to achieve with this setup.