My lightmaps look great, but they look terrible when applied in the scene

For the last two days I’ve been baking and rebaking tweaking the various parameters and taking notes. I’ve also removed many unnecessary scene assets and decreased the proportion of many assets in the light map.

I think the lightmaps look good. The comp_light:
image

comp_dir:

But, this is what things look like in game:

image

I have tweaked the following ranges:

Baking real-time global illumination on and off
Baking real-time indirect resolution 4 - 8
Baking with Real-time Environment Lighting on and off
Importance sampling: only on
Direct samples: 256 - 2048
Indirect samples: 256 to 1024
Environment Samples: 256 to 1024
Light probe sample multiplier: only 4
Max bounce 3- 8
Filtering: None - Auto
Lightmap resolution: only 50
Lightmap padding : only 4
Lightmap compression: Normal, high
Ambient occlusion: Always on, distance 3, indirect 3, direct 0.
Directional mode: Directional and non
Albedo boost: only 1
Indirect intensity: 0.5 - 1

I have been using probuilder to merge ceilings to ceilings, floors to floors, and walls to walls. This has been very helpful to eliminate huge seams.

I have not found any rhyme or reason to how many lightmaps are created. I can get massively different sized output, from ~200 MB to 1.2GB with very little change in appearance. For example between two bakes I decreased the lightmap scaling for several large meshes from 0.25 to 0, and increased direct sampling from 1024 to 2048. This increased the lightmap size from 458 MB to 1.2 GB (!).

My latest images, from which I am drawing here, are 84 1024x1024 directional lightmaps @ 224 MB with no baked realtime lighting.

I could really use some advice cracking this riddle. Thank you!!

Might be texture compression or encoding. Try disabling those. Lightmap compression can be disabled in the lighting window, and lightmap encoding can be set to High Quality (meaning no additional encoding) in Project Settings > Player > Other Settings > Lightmap Encoding.

Thank you! This actually worked. I switched lightmap encoding to high quality. Things are almost entirely cleaned up. I’ll try one more bake with no compression. Thank you.

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