What causes baked GI light leaks?

Light leaks through walls because the geometry is too thin for the lightmap resolution, the wall is single-sided, or probes sample across the wall, so indoor areas pick up outdoor light.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix Light Leaks in Baked Global Illumination

Quick answer: Give walls real thickness, raise lightmap resolution where leaks occur, and place probes and geometry so light does not sample across thin barriers.

Baked light leaks are thin geometry versus lightmap resolution. Here is how to fix them.

How to fix it

1. Give walls thickness

Single-plane or paper-thin walls let baked light leak through because the lightmap and probe sampling cannot resolve the thin barrier. Give walls real thickness so light is properly blocked.

2. Raise lightmap resolution at leaks

Increase the lightmap resolution on surfaces near leaks so the baked lighting has enough texels to represent the shadow boundary at the wall, rather than bleeding across it.

3. Fix probe and geometry placement

Keep light probes from straddling thin walls (which makes objects sample outdoor light indoors), and ensure occluding geometry is present so the bake blocks light correctly between spaces.

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.

The bug you can't reproduce isn't gone — it's just invisible until you capture it from the player's device.