Hi
I’ve been running into this issue while trying to bake the lighting.
as you know it’s due to the main UV channel being a hectic mess (shown in the pics), therefore the generated lightmap UV chanel is going to generate the ‘‘50% overlapping lightmap UV’’ error after the bake.
1st - Why the hell is this normal in marketplace nowadays? Is it a lazy work or an Unreal issue that artists don’t want to deal with?
2nd- How can you solve this within the engine itself without taking 100 assets into 3ds max to rewrap the UVs?
Unreal has an option to generate lightmap UVs on import, in most cases all you need to do is make sure you check that checkbox when you import.
If you’ve already imported them and you’re trying to generate lightmap UVs after the fact then you’ll want to also make sure that you have set it to use the correct lightmap UV channel, if there was only one channel when it was imported then it will use channel 0 (while generated lightmap UVs are typically stored in channel 1 by default)
Hey Arkiras.
Thank you, I imported these directly from the FAB, my library into the project. that import window doesn’t pop up when importing this way.
Yes i have the lightmaps index coordinate set to 1 or 2, which ever channel that’s generated for lightmaps.
I think the issue is the original UV channel, channel 0, is a mess, like the pictures, and the generated lightmap channel creates overlapping error messages.
I’m wondering if I can rewrap this clean in engine as I would in 3ds max with just 2 clicks.
It’s normal for the regular texture UVs to overlap and exceed the 0-1 space. For regular tiling textures it does not make sense to give them all unique UV space. Modern game art workflows rely on trim sheets which makes UV layouts like this inevitable.
It should not be an issue though, as Unreal’s lightmap UV generator should be able to handle this in most cases. It will repack all the UV islands inside the 0-1 space without overlapping the islands. The only instance where it should fail is in instances of self-overlap within an island (because it only packs the islands, it doesn’t reunwrap the mesh). This isn’t that common and it’s not really clear from your screenshots that is happening. Generally speaking, if the issue is self-overlap from within UV islands the overlap percentage will be much lower, like 3-10% at most, so that’s unlikely to be what is going on here.
Most likely, either the lightmap UVs werent generated correctly by the editor (not sure what the current state of the FAB plugin is…) or its not using the right channel. I’d flip through them and look at them individually to try to find the one that looks right and make sure you’re using it.
Probably possible with the modeling tools plugin that ships with the editor, though I’m not particularly familiar with it so I can’t give you any guidance on using it.
Thanks for your replies man.
These listed on the after bake error list are the only ones that are not fixable no matter what. as you can see some are below 8% and the rest are stuck at 50%~.
The rug picture is showing one of the UVs, channel 0 (the messy one) and chanel 2 (the generated one for lightmaps) and this is the one with 48% overlap .
