I try importing with generate lightmap uv checked on… and i have no uv lightmap in the editor when the model is imported. I also went to the models properties and checked it in there… still it does nothing. Is generate uv broken? Am i forced to do it in my 3d package?
Hi Kurlyo3d,
I’ve not experienced any issues with using the generated lightmap UVs. There are stipulations to using it though since the generated lightmaps will not create seams or break apart the UV chunks, it will only repack UV Channel 0 into UV Channel 1.
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Thank you!
Tim
Well heres the thing… destination lightmap index doesnt even exist as an option modify. I remember that option so i was looking for it and its not there at all. My UV zero has its own chunks already, but i didnt want to have to create another uv set by hand or even duplicate the uv set inside my 3d package. Right now… its just simply not creating UV channel 1… and i dont ahve an option for destination lightmap index …
Is this only happening for this mesh you import or is it any other mesh including the ones that are in the engine folder? Looking at 4.10.1 and 4.11 P1 I’m not seeing this on my end. If this is the case would you mind posting a screen shot?
All the options are available under the Build Settings in my Static Mesh Editor.
If it’s happening with a particular mesh, would you be willing to share this mesh that reproduces the issue?
I’ve had this too for some models. It might happen for models that have a lot of smal meshes (I had a palm-tree). I could solve it by increasing the “Min Lightmap Resolution” in the LOD0 settings and then pressing Apply Changes. I increased it with factors of 2x at a time. Resolution 128 was enough. I once tried 1024, but then UE hung at 0%. For another model the Light-Build-phase set that even the generated UV’s were overlapping; increasing those also to 128 solved the problem. This is in UE 4.11. Hope this helps.
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THANK YOU!!! THANK YOU!!! THANK YOU!!! THANK YOU!!! I have been looking everywhere for a fix to this problem (I had a bush with this problem). This fixed it for me. Thank you! 
@kurylo3d
I’m having the same problem. Using unreal 4.26. things have changed. some uv’s are not created have tried everything. and there is no apply anymore. so you change the small existing settings and nothing changes
this was a long time ago so its hard to recall, but try checking your models scale and export / import settings… sometimes if it comes in too small and you choose a larger import scale in unreal it messes things up… like sometimes it just needs to come correct from your 3d package first. That sort of thing has also caused me issues with collision meshes it generates in the past.