UV texturing issue

[vfx]

I've come across this issue a couple of time when working in Mudbox... When I'm making some hard edged object where the face count might be higher when subdivided, I think mudbox seems to struggle with the uv's being so close and ends up stretching the texture I'm painting/projecting. How do I solve this? See attached image for an example.

http://www.cgfolio.co.uk/cgtalk/muduverror.jpg

[Darkghosty]

Looks like the UVs are compressed in that area which is causing the texture stretching. Can you post your UV layout? I had this happen a few times after I sculpted up an area, I had to take my low res back into my 3d app and adjust the UVs so there wasn't any stretching.

[vfx]

Hi Ryan,

I have kinda solved this with your help, but its definitely something thats not working correctly in Mudbox.. if we look at the lip edge in my example, to get that hard edge, I did the usual thing to keep hard edges when the model is subdivided - bevel edge (two edges very close together) - so when I did the uvlayout, I do everything to porportion and this means these two edges are less than a couple of pixels apart. This isn't a problem in Photoshop when I paint across and view the result in maya, but it seems to throw mudbox off when u paint in the program. I went ahead and increased the gap in the uvlayout between these edges and the problem goes away.

Why is this happening

See example...

http://www.cgfolio.co.uk/cgtalk/mud_uv.jpg

[vfx]

Actually, it doesnt seem to be the re-positioning of the uv's that fixed my problem, but rather, if I turn off the sub-d option 'Smooth Positions' - This isn't a problem either in my case as I've done the work already for smoothing the edges in maya... so with this option off, the texture stretch problem goes away.. an interesting thing to ponder on.

[Darkghosty]

well glad I kinda helped ;)

Curious what software are you using to unwrap your model? Are you using headus or maya or something else? Also when you unwrap it are you able to see the stretch colors? Are they all in green or are those small bevels in blue or red? I know when I had this problem and I originally unwrapped my model those small hard edges were actually a little in the blue, once I stretched them out a little so they were green the problem went away.

On a side note (i havn't tried this as my trial at work expired), but I know some people mention re-creating level UV's (in the mesh menu) within mudbox at the subdivision level you are on. Again I havn't used this yet, but in your experimenting it might be worth seeing what this will do.

You'll have to forgive me i'm still pretty new to mudbox also so i'm really just taking stabs in the dark :)

[vfx]

We're all pretty new to the app really.. afterall 2009 hasn't been out for long. ;)

I had funnily enough already tried your suggestion on recreating uvs and it didn't make the slightest difference.
I do infact use headus uvlayout coupled with maya uv editor - I always try and aim for green :) And thats exactly what these small faces were.. so it was proportional. I've strecthed them out some, and that coupled with deselecting 'smooth positions' seems to be the only solution. Issue is you don't get quite as nice a smoothing but it shouldnt matter as I will be using mayas smooth tool and not mudbox's.

Cheers mate.

[Darkghosty]

Good to know either way. Right now i'm using Roadkill for unwrapping while I save my pennies for Headus... it's a pain to say the least :)

[vfx]

Headus aint so bad.. it's only 200 dollars £140 for the hobbyist. Still a little too much given I rarely unwrap that much. If you download their trial it will last you till mid April. :)

[Darkghosty]

Yeah i was thinking about forking over the cash for the pro version, but I didn't know they changed the trial so you could save stuff out.

Before I tried out the trial here at the office and you could use it as many times as you wanted to unwrap objects, but you couldn't save out the unwrap when you were done. I didn't realize you could use the demo to save out your unwrap, good to know :)