How to Fix Baked Light Bleeding Through Thin Walls Into Dark Rooms

Baked GI traces light through your geometry, and a paper-thin wall does not stop it: bright outdoor light bleeds into the dark room. Giving walls real thickness and enough texels blocks the leak.

How to fix it

1. Give walls real thickness

Model walls thicker than a lightmap texel so a ray cannot skip from the lit side to the dark side within one texel. Single-plane walls are the most common cause of bleed.

2. Use solid, closed geometry

Replace single-sided plane walls with closed solids so backfaces actually occlude GI rays. Open or non-manifold walls let light pass straight through.

3. Raise local lightmap resolution

Increase texel density on the wall and adjacent surfaces so the occluding boundary is resolved finely enough to stop the bleed.

4. Check backface and two-sided settings

Ensure the material/bake is not set to ignore backfaces or treat geometry as two-sided in a way that lets light pass; then rebake.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.