3DS Max: How to avoid relax errors in UV unwrap?

JordanN

I'm trying to unwrap an extinguisher.

I select a ring of polygons, use cylinder projection, and then relax. But when I do, I end up with these "dragons" or "snakes" where the uv island doesn't fully relax properly.

I increase the iterations but it still looks ugly. "straighten selection" also doesn't work.








Edit: Ok, I tried adding stretch and got better results but now it looks super long. Is this the only solution and is it feasible?

circle of friends

Cylinder unwrap is pretty bad and unless you know what you're doing I'd not normally use it.

For this, what you want to do is grab the entire element, do a planar unwrap then deselect it. Then select the bottom faces, do another planar unwrap and move that element to the side. I can't see what the top of your model looks like but where-ever the cylinder shape stops then select the row of edges and break them (cntrl+b with keyboard shortcut override toggle on).

Now what you should have is the main cylinder as a planar element and the bottom of the cylinder as a planar element.

Now grab an edge on the cylinder, hopefully the edge that will be seen the least, or the edge that is less likely to have any stickers or writing on etc and break that edge.

Now select the entire element, go to relax, change it from edge angles to face angles and press relax. That should sort it out. If it doesn't, try edge angles. If THAT doesn't work then try flipping the UV element and relaxing again. The reason why you're getting messed up relaxing is because you either don't have enough break/seams in your mesh for it to flatten out, or your element uv is flipped.

Mark Dygert

I'm not really sure why you are unwrapping each part of the cylinder individually?

There are a few different ways to uwnrap this but the easiest is to just use cylinder unwrap which will get it pretty straight and flat and then relax it and straighten it.

Straighten will fix tiny uneven lines, it won't untangle a mess.

If you're trying to relax a circle into a flat line that "can work" but can lead to what you've got going. Switching to face angle or edge angle will help but really you shouldn't be trying to change a vertical projection into a horizontal projection. Start horizontal and stay that way.

snoop

Relax seems to only work well if you use pelt mapping as opposed to planar or cylindrical, etc. At least, this has been my experience.

Mark Dygert

I use relax with cylinder and planar projection, all the time. My main method of unwrapping involves planar mapping the entire object, creating seams, breaking and then relaxing, or just selecting faces and hitting quick peel which skips to the end result of the relax function.

Relax will have trouble unfolding long flat strips of polys. So it would help to unwrap it all, at the same time and then break it apart if you need to.

Try this:
Planar map the entire object.
Quick peel the top and bottom polys.
select a vertical loop and break it.
Select the main element and hit quick peel.
Straighten it and pack it all.

snoop

If Mark's method does not work (not saying it won't or that you're wrong, Mark), I would still give the pelt mapping a try, as a matter of last resort or of the many things you may have to try to get around this issue.

Mark Dygert

Yep, there are a lot of ways to pull it off, just gotta find one that works

JordanN

I just woke up. Gonna restart it.

Mark Dygert wrote: »

I'm not really sure why you are unwrapping each part of the cylinder individually?

I'm following this tutorial.
http://cgi.tutsplus.com/tutorials/create-a-game-ready-fire-extinguisher-with-3d-studio-max-part-3--cg-31947

It recommends breaking up the main tank and other parts of the extinguisher and unwrapping them through cylindrical projection. Although my extinguisher differs slightly so I gotta unwrap those (I kept some extra polygons in some areas as well as removed others).

divi

do you mind uploading your model? i have yet to meet a cylindrical shape that "straighten selection" - "quick peel" - "straighten selection" doesn't fix. just out of curiosity.