Static mesh lighting issue

I made a house model and unwrapped all the parts. I also made a separate lightmap UV set.

The issue I get is that the ceiling of the house appears to be lit up way too much. I checked the normals and they all seem to be fine (all the faces are visible in game too).

In the mesh settings I set the lightmap resolution to 256 to try and resolve the issue but that doesn’t seem to help.

Heres a picture of the lighting issue:

I also tried making the glass on the right side of the image opaque to stop light coming in but Im still getting some light issues.

What causes this and is there anything I can do to resolve the issue?


Just to make sure I get this right: You think the bleached/white upper wood panels are too brightly lit?

I think he means the weird stuff on the walls

Can you verify that you specified the correct light map coordinate index on your static mesh settings? Sometimes people forget to set that and it may default to 0 if you first imported the mesh with only 1 uv set.

If that isn’t the issue, can you change the view mode to light map density and verify you have good UVs as read by the engine? You can also preview the UVs in the static mesh editor.

Also, what was the quality setting or your lighting rebuild? You should not got artifacts like this, but preview can cause some roughness in the more ambient areas that rely solely on indirect light.

The ceiling/upper wood panel texture seems too brightly lit to me. When I move the camera into the room from the outside, the room is completely hard except for the ceiling which I can see fairly clearly in the dark. The lighting in the room slowly adapts and reaches a normal level, but the initial bright ceiling just looks off.

Just some context to the image, it is the upper floor of a house mesh so there is a mesh outside of the things you see in the image. There’s a roof just above the ceiling and external walls.

The bright stuff on the walls seems to be related, since it, and the lighting on the ceiling, doesn’t happen on the ground floor of the house.

I think I might have found a solution though. Improve the lightmap.

I use the unwrap feature in Blender that produces a load of square UVs(it’s specifically for lightmaps). I don’t know if that’s ideal.

Are there best practises to producing a lightmap?

You can reach the best result with the “smart uv project” generator in blender:

Also make sure that you have a lightmass importance volume in your level

Thanks for the responses.

I double checked and the lightmap was set to the second UV set. I was using the preview lighting mode so I guess it makes sense if the lighting it’s not perfect. I also checked the lightmap density and it looks all distorted in some areas. I think that’s probably because of the lightmap unwrap mode I used.

I’ll try the Smart UV Project instead of the Lightmap Project. I’m just testing in the FPS example map and the importance volume surrounds the whole level so that seems fine.

I’ll report back after trying the above.

Right, the smart unwrap solved the light map density issue. Changing the lighting quality to high has also sorted out the wall and ceiling artifacts.

Now, the rooms are initially totally dark as expected and when the HDR lighting catches up the walls are nice and evenly lit :smiley:

Thanks for all the help guys it works perfectly.

Cool that it worked out :slight_smile:

By the way, you might also want to look at the eye adaptation that takes place. Sometimes, if you want to have a dark scene, that can bite you (I had a similar issue with a night scene).


Good to know.