Author Topic: UDIM bug in painter 2020.2.1  (Read 1514 times)

Hi There,
I am using the new UDIM workflow in painter 2020.2.1 and I have discovered what I believe is a bug. I have a case where if I use the UV tile mask to hide / show certain UDIMS it is also affecting what is visible on other UDIMS to that one. It is like that UDIM has some paint on it which stretches out to outer udims so that if I hide it, it is actually hiding some paint which is on another UDIM too.

Is there any case where this is expected and I am misunderstanding what is going on? I'm pretty sure it shouldn't be doing that and it is a bug. Any ideas?

Loving the UDIM feature so far but this has caused a full working day of confusion and now I figured what it is doing at least, but it seems like a bug which makes my project hard to continue with...


That's the expected behavior, although I agree it can be confusing at first because no other tool behaves this way afaik. Since everything is non destructive in Substance Painter, the mask only masks strokes as long as it is active. If the mask is deactivated, the data from the original strokes is still there and those strokes are re-drawn as if there was no mask.

Hey Jeremie,
Thanks for the reply. I'm not sure I'm describing the issue very well . I understand substance stores the strokes non destructively and that even when you mask a udim the strokes are still there and will be applied if the udim is unmasked, but what I am seeing is unmasking for example udim 1003 makes paint strokes appear on udim 1005. So it seems like in that case udim 1003 has some paint data which is spilling onto 1005. Does that make sense? And would you say that is expected? I can't see how it would be as it makes managing udims very difficult.

I am primarily using the UDIM masking to lighten the project in the viewport so hiding most of the udims except the few I am currently working on. But it seems when I re enable the other udims I seem to get random paint strokes linked to the ones I have been working on so it is a bit of a russian roulette as to if I am messing up the hidden udims.

I am working on an active production so I can't really post screengrabs or videos unfortunately as that would make it a lot clearer. If it would help I could send a private link to you to show the problem.

Thanks again

Indeed that seems like a different issue. Would you be able to send me more details and files at Thanks!

I checked with my production and unfortunately I am not allowed to send any show material at all which is frustrating. I'll maybe try to recreate the issue with simple geometry if I get some time and post pictures.