Ideal UV mapping in Substance Painter

[sha19899999]

Hello, I have a question about UV mapping in Substance Painter.

As in the attached video, if there are two or more identical star-shaped meshes with front and back sides, what would be the ideal way to map the UVs for the meshes?

In the video, the front and back UVs are separated and positioned far apart, while the left and right UVs are overlapped. Will there be any errors or problems when baking in Substance Painter?

Is it always better to split the UVs into four without overlapping them?

Thank you in advance.

[Cyril Dellenbach · Accepted solution]

Hello @sha19899999 and thank you for the video.

Overlapping is always a complicated topic if you're unsure of Painter's behavior. In your example you'll probably don't have an issue. However, your example is far from what you'll probably face in real workflows.

Problems occur when you have 3D objects sharing UVs, but aren't at the same location in the 3D scene. Some Bakers (AO, or Position, etc.) are using the object's position/rotation to build their mesh map. What happens to the AO if two objects sharing UVs shouldn't share the same AO? That's when artifacts are appearing.

That being said, overlapping is a really efficent way to optimize UV space, so I'm not saying you should never overlap UV shells, but if you do, be sure to think ahead whether this will be an issue at the texturing phase or not.

Best regards,

[sha19899999]

So it's not that "UVs must never be overlapped," but rather that it's okay to overlap them as long as no errors occur depending on the situation?

Thank you very much.
This was very helpful.