Random Blocky Lighting

I’ve begun work on a little project that spawns a couple of blocks (using an instanced static mesh component), and I’ve just encountered this inexplicable issue: these few cubes are lit even when the post process cubemap and sunlight is disabled (everything else is black but these particular polygons are still lit).
Can anyone help me fix this annoying bug?

Hi Oscar,

You can read about this on my Wiki Lighting Troubleshooting and Tips page here: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums

There are some tips to help you reduce this, but largely it comes down to how the assets work with indirect lighting and how the UV was setup if it’s a single asset.


But surely if all light sources in the world are disabled then there should be no light at all?

From the screenshot, it doesn’t seem that all light sources are disabled. If you’ve got any light sources including a skylight that is set to Stationary or Static you’ll see this as well after building lighting.

Also, keep in mind that if this is a single object, UVs can play a part in this as well with non-connected UV islands.

No, when I disable all the lights, they are still lit.
And as mentioned, its an instanced static mesh with multiple instances of a cube.
Also, the sides that are extra-lit are not static, they change every now and then.


Could it possibly be related to your Environment Color? Check your lightmass settings:

I doubt it, since the blocks that are extra-lit change every now and then.