Sorry, I know there are millions of posts about this topic but I’ve tried most of the suggestions I can find without fixing my issue.
I have a large nighttime scene with 14 static meshes and 113 lights of various types, all set to static. When a lighting build has been completed, some of the meshes remain lit but some of them turn black (and one of the turns blue!) until I move either the affected mesh or the lights then the lighting returns, until I run a lighting build again and those meshes go black again.
I’ve tried overriding the lightmap res on the affected meshes, setting them from 32 to 4096 without any luck. I’ve tried mapping the UVs again in maya and using those as the lightmap UV without any luck. The map check log returns 0 errors. The only errors I get in the lighting log mention “Lightmap UV are overlapping by XXX%. Please adjust content - Enable Error Coloring to visualize.” on 2 of the meshes, but those meshes aren’t black. I’ve tried building wit error colouring on but the affected meshes just appear black still.
Edit: I’ve tried building the lighting with the same meshes in a different scene with only a directional light, and they’re still black, so that indicates a problem with the meshes themselves?
Thanks, and sorry again about asking this question!
The only errors I get in the lighting log mention “Lightmap UVs are overlapping by X%. Please adjust content - Enable Error Coloring to visualize.” on two meshes, but those meshes aren’t the ones that are black :-(. In this screenshot, the darker blue shapes are the ones that are black.
So… usually when your object turns black after light build it’s due to not having a lightmap uv!! You should check those objects if they have any uv mapping information and if they do maybe you’ll need to change what uv channel your object should use for lightmap! If you don’t have then you can try to auto create one with Unreal or go back to your 3d app and create your own!
Lighting coming back after moving an object:
When you first place an object into the scene they show up as dynamically lit!! …same happens if you move an object! So basically this is what’s happening: you build your lights, you have problems with your lightmaps, so you’ll get false (or non at all=black result) lighting results. Then you move your mesh and it will be shown the default dynamic look!
EDIT: Changing the index to 1 or 2 doesn’t fix it either. Channel 0 has come from maya, I presume channel 1 has been auto-generated from unreal, and 2 appears to be blank.
If that’s your lightmap UV then it’s very bad, looks like you used automatic mapping which often gives bad results. Ideally, you want to unwrap it yourself so that you can do a better job
for best results, use as few seams as possible and try to keep the UV islands similar in size and try to use up as much of the UV space as possible. In your case, you may need to split up the mesh into multiple pieces to get enough detail because it looks like it’s a large mesh and you can only use one lightmap per mesh.
In your case it also might be the lightmap resolution that’s the main issue there, if you didn’t change it from the default then the default is 64x64 pixels which is way too small for that.
increasing the lightmap resolution to 4096 does fix it somewhat (it’s not black anymore but the lighting result is quite bad). Breaking the mesh up into smaller parts makes sense, I’ll try that. I’m not particularly good at manually unwrapping UVs, so hopefully the auto generated ones work if the meshes are smaller. Thank you!
I don’t know if *Datasmith *is still free for testing/using/registering but it does a VERY good job on auto (uv) lightmaps! 95%-100%!! …the remaining errors are easy to adjust…
UV mapping looks scary in the beginning but it’s not difficult at all!! …and once you learn how to uv map for lightmaps it’s even fun to do! …but again lately *Datasmith *does almost everyting!
- can anyone help please?
…but again lately *Datasmith *does almost everyting! 