Error : Object has wrapping UVs

Development Rendering
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1

Hello,

I am building a stadium.

I am converting a stand made of geometry brushes to static mesh (no materials applied). After I build I get this error , and the lighting/shadows on the mesh are screwed up.

What does this mean and how can I fix it ?

2

It means that the specified light map coordinate has overlapping UVs. You can try fixing it by opening your static mesh in the viewer and using the auto UV tool. It should create the new UVs in channel 1 by default but you will have to change the lightmapcoordinateindex setting to match.

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This is what I am seeing if I toggle the UV.

Haven’t managed to found auto UV tool yet.

4

Hi Robbie222,

When you open the mesh viewer you’ll need to go up to “Window” in the menu bar and select “Generate Unique UVs”

This will open up a new window under the details panel to the right.
Hit apply, as the defaults should get you started.
In the details panel you’ll need to find where it says “Lightmap Coordinate Index” and change that from 0 to 1

You can reference this image as well.

If you have any questions feel free to ask!

Tim

10387-generateuvs.png
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Thank Tim for the detailed how to. It did help with getting rid of the errors but the lighting/shadows are still not how they should be. I have created a topic on the forums regarding this issue with more details.

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Thanks for linking the two. :slight_smile:

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thanks a lot i had problem with objects not showing in android and this fixed it .

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These options do not look exactly the same in 4.10. Much of it is streamlined but you still need to update the Light Map Coordinate Index to 1.
Thanks for the tip Tim

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You’re right, Nick. With 4.6 there was a change in generating Lightmap UVs.

Anyone interested can find the current use and setup on our Support Wiki here: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums

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When I had this problem I realized that you need to have a texture as your material. It won’t work with just a color set as a material. Unreal engine 4 don’t know where to start generating the light map, but if you have set a texture UE can use that coordinate to generate the lightmap. UE can’t generate a lightmap on it’s own.

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When I had this problem I realized that you need to have a texture as your material. It won’t work with just a color set as a material. Unreal engine 4 don’t know where to start generating the light map, but if you have set a texture UE can use that coordinate to generate the lightmap. UE can’t generate a lightmap on it’s own.

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Any updates for UE5. I’ve object meshes downloaded from Quixel Bridge that have this error.

How do we fix it now?

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13

Open the mesh in the mesh editor.

  1. In details - under LOD 0 / Build Settings (expand) and check the box for Generate Lightmap UVS.
  2. Scroll down a bit and click Apply Changes button.
  3. In details under General Settings set your Light Map Resolution to desired (64)
  4. In General Settings expand Advanced and set Light Map Coordinate Index to 1.
  5. Save the Mesh, Build Lighting only and check warnings.

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6 Likes
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I’ve tried everything people have said and have followed all the YouTube tutorials on how to fix wrapping UVs but nothing works

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15

I randomly have this issues on models i make in the engine, but today finally i was able to resolve that issue.
In addition to above to get in the right light channel -

  1. Goto Modeling Mode and click AutoUV “default settings worked in my case”.
  2. Then goto UV “Layout” and tweek your scales if needed.

I fixed 9 in engine models this way after they where in the write channel " 1 ", not 0.

1 Like
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Thank you! It works!