Good day everyone,
I’m currently learning the ropes of Unreal Engine 5 and I’ve run into a lighting issue that didn’t appear in the tutorial I’m following, and I haven’t been able to resolve it on my own.
The problem
I’m trying to bake lighting for an assembled scene made of modular pieces.
After building lighting, the result looks incorrect: the lighting does not propagate smoothly across adjacent modular meshes. Instead, each piece appears to be lit independently, resulting in a very noticeable checkered / patchy lighting pattern across flat wall surfaces.
Lighting setup
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HDRI Backdrop
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Skylight driven by the HDRI
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Skylight set to Static
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Lightmass Importance Volume present
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Box Reflection Capture
Interestingly, when the Skylight is set to Movable, the issue completely disappears and the lighting looks correct and smooth.
What I’ve tried so far
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Verified lightmap UVs (non-overlapping, correct channel)
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Checked lightmap density (mostly green)
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Increased lightmap resolutions
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Rebuilt lighting multiple times
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Ensured consistent texel density
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Followed the tutorial click-for-click and principle-for-principle
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Compared results directly with the tutorial (their scene does not show this issue)
Despite all this, the problem persists only when the Skylight is Static.
Question
Why does setting the Skylight (HDRI) to Static cause this lighting breakup across modular pieces?
Is this a limitation of Lightmass with modular geometry, or am I missing a crucial setup step that allows static skylight baking without visible seams?
I’ve attached screenshots showing:
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The checkered lighting artifact in Lighting Only view
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Lightmap density visualization
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My lighting actor setup
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HDRI Backdrop settings
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What the environment looks like when Skylight is set to “Movable”
Any clarification or recommended workflow would be greatly appreciated.
Thank you in advance!