Overlapping UV's

Hey guys,

i just started to port over my UDK Stuff to UE 4. So i exported all meshes as .fbx and exported the Textures as .tga. After i imported them and reassigned the Materials i always get an arror when building my lightning.


Strange thing is i never had any UV Problems with that content in the UDK. After building the lightning the shadows looks weired then of course.
Any help is appreciated :open_mouth:

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Create a 2nd uv channel in your 3d program, place a lightmassimportance volume and then build the light

Doesn’t work for me.
I already have an Lightmassimportance volume and my mesh does have UV Channel 0 which is Blank and UV Channel 1 which contains the correct UV

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By default UE4 takes UV Channel 0 for the textures and UV Channel 1 for the lighting.

If Channel 1 is for Lightning shouln’t it work then ? I mean Channel 1 has the Mesh info in it.
So basicly it should work or am i wrong =?

on some models you can get away with only having 1 UV, for example if you made a basic barrel and layed out the UV so there were no overlapping faces it would work for displaying the texture and would also work as the lightmap. although most models will need to have 2 UV’s.

we couldn’t say for sure if your models UV should work or not without seeing how you’ve done it.

If you imported the mesh without a lightmap, UE4 will set the lightmap channel to 0. If you then import it later on with a second UV channel you have to manually go into the mesh and tell it to use channel 1 instead of 0 … could that be the issue?

Got it fixed ! :slight_smile: UDK didnt export my UV Channel 1 so i just created a new Unique UV Channel inside UDK exported now and voila its working :slight_smile: