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I am having a problem with my exported texture maps from painter to UE (4.26). Everything looks great in Painter (1st image), however once importing to Unreal some (but not all) textures seem to be shifted with respect to the UV maps (I used a UDIM/Tiled workflow from blender).

I found an older post that recommended triangulating the mesh from Blender 2.91 (I used triangulate modifiers at the end of the stack on all objects w/ the “Keep Normals” checked on. These modifiers are applied at export of the FBX)

Painter Viewport: enter image description here

UE Viewport:

enter image description here

Painter Export Settings:

enter image description here

Since the problem doesn’t exist everywhere (actually most of the texture maps/UV are aligned correctly in UE), I’m not sure the UDIM workflow is to blame here, maybe it’s my FBX import settings? Maybe something to do with the creation of the virtual textures from the UDIM maps?

Anyone run into this problem before? Any clues as to what I should try are welcomed (I can provide more screenshots/info if needed)

Thanks!

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  • $\begingroup$ Hello and welcome, you need to check how the Unreal support for UDIM's is, also make sure that your textures has the correct names $\endgroup$
    – Emir
    Commented Aug 5, 2021 at 1:44
  • $\begingroup$ Thanks for responding Emir. UE4 supports UDIMs by generating a virtual texture that is the dimensions of the UDIM tile map (mine is 10x1 so 20480x2048 is the generated virtual texture's resolution). It uses the standard xxx.1001.png name matching when assembling from all of the 2048x2048 UV tile maps. So, all good there. As I said above, most of the textures are aligned correctly to the model exported from blender/imported straight to UE4, but those images above show just how bad it gets in some places! $\endgroup$
    – Slavkosky
    Commented Aug 5, 2021 at 5:17
  • $\begingroup$ I have a similar problem solved by shifting the problematic UDIM closer to the zero UDIM $\endgroup$
    – Василий Киселев
    Commented Feb 9, 2022 at 14:17
  • $\begingroup$ I eventually enabled "Use Full Precision UV's" in: Static Mesh Editor > Build Settings. This fixed the issue immediately. --- Although UV's are 0.0-1.0, in UE they must be using lower precision by default for performance reasons. UDIMs are beyond 0.0-1.0 (my UDIM layout was 9 maps), so there is going to be precision loss/rounding errors without using full precision UV's option. $\endgroup$
    – Slavkosky
    Commented Aug 3, 2023 at 22:43

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I eventually enabled "Use Full Precision UVs" in: Static Mesh Editor > Build Settings. This fixed the issue immediately. You have to enable this for each mesh you're using UDIMs on.

Although UV's are 0.0-1.0, in UE they must be using lower precision by default for performance reasons. UDIMs are beyond 0.0-1.0 (my UDIM layout was 9 maps), so there is going to be precision loss/rounding errors without using full precision UV's option.

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