Unmapped models in UE4


I have following image on UE editor, where model gets wrong lighting with the shown error messages. Model itself is comprised from many Skekcthup components e.g. curly vertical posts, horizontal curved glass panels and connector parts, each one is modeled and unwarapped seperately in Blender and exported to fbx file. Even though model has unwrapping UE editor still shows that model has overlapping UV’s.

Is it due to each component is handled and unwrapped individually or I should treat them as one full entity ?


OK first of all , I need to clarify one thing form my perspective I was assuming that UV lightmapping and mesh unwrapping are equivalent to each other(simply different naming conventions), but based on your post it seems that they are not and I have to create two UV unwrappings first for the textures and second for the lightmapping, and to diffrentiate them first channel for UV unwrapping and second channel for lightmapping ( all this to be done in Blender), please correct me if I’m wrong?

When it comes to UE4 UV editor mesh browser I can see the UV unwrapping, they are quite neat and tidy they seem like aligned (please see image) properly but UE4 editor reports those previous errors. I also can not modify any edges, vertice in the UE4 editor, so that means I have to use external program (Blender, there is nice feature in it like Smart UV Unmap ) I don’t know exactly if there was any way in UE4 to manipulate the unwrapping?


If the pieces are imported together as one mesh UE will combined them as one even if they are all done separately, you will need to set them up on one UV map all together and setup a separate UV for lightmap or let UE auto gen the UV for lightmap. To take a look at what UE has as the UV open the static mesh editor and then click on UV :


That should show you what UVs UE is using for the model, you can also change which channel you are viewing using the UV Channel drop menu that is next to the show UV button. Wrapping UVs is when the UVs are out side of the 0 to 1 range on the texture, they will have to be arranged to fit within that space to work correctly.

Yes UV for texturing and UV for Lightmap are separate and just because they look nice and neat doesn’t mean they aren’t overlapping in Blender is there stat check/ xView like 3ds max has for you to check for overlapping UVW faces? I have never used blender sorry.

There isn’t a way to modify the UV edges, verts or polys, there isn’t a way to manipulate the unwrapping in UE4 other than to have it auto-gen lightmaps based off UV channel 0 (the first one).

OUCH! Those are without a doubt overlapping(Yours that is).

OK that seems to be the case for me, thank you very much for enlightement. Should I arrange the channels for lightmap/unwrapping in 3DSMax ?

Here’s an student file example I grabbed real quick of a nice an neat looking UV unwrap:

Looks good right? Nice spaced and arranged fairly well…at first glance…but it is not:

That’s right around 92% overlapping for this model

You don’t have to use any particular software just as long as the unwrap is laid out appropriately.

This may be helpful as well: