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16 Aug 2009

Hello. My name is Josh, and I can't lay out UVs.

I've never been much of an artist, but as I got into game design I found a need for certain art skills. Now I'm pretty well-versed in Photoshop, and can model okay, but one thing that's still eluded me is UV layout. Today, I decided to change that. After a bit of Google-fu, reading a few tutorials, and about three hours of mortal combat with Maya's UV editor, I had successfully mapped... a crate.

Now granted, we're not talking a literal cube. I inset each face, and wanted to map part of my source texture to the inset faces, another part to the internal edging, and a third part to the external edging. Here's the division I was going for:


Still, this seems like it should be pretty trivial. I made selection sets for the inset faces, inset edges, and external edges, and got after it.

There are a few things that really mess with my head in Maya's UV editor. One is that, while it's intuitive enough to select faces (for example) in the Perspective view and see those faces highlighted in the UV editor, I can't actually manipulate the UVs from this state: I have to convert the selection to UVs first. I lost a lot of selections this way... very annoying.


The second thing that trips me up is that I'll grab a face and set up its UVs appropriately, only to discover that I've now totally fucked up the UVs for adjoining faces. The answer to this seems to be the "Cut UVs" command, which half the time didn't seem to have any effect at all. Not to mention: I can't do it on a face, I have to convert the selection to edges first, so there's another manual selection-convert step in the process.

Once I worked that out, I figured it'd be easiest to lay out one representative face and then copy and paste those UVs to its like faces. I don't know if I misunderstood those commands, or just ran into a bug, but after I did that once -- and it worked swimmingly -- subsequent copy operations would have no effect, so I could only ever paste the very first set of UVs I'd copied. I had to restart Maya to do a second copy-paste operation, which seems less than optimal.

Even after that, I was only able to paste UVs for the inset faces; trying the same approach on the inset and external edges did not yield happy results. I got some pretty scrambled UVs out of that; there didn't seem to be any rhyme or reason to the results. So for these cases I ended up doing the following for every face:

  • Select face
  • Convert selection to edges
  • Cut UVs
  • Re-select face
  • Convert selection to UVs
  • Move UVs into position

All the inset edge faces shared the same part of the texture; similarly, all the external edge faces shared another part of the texture. Since I couldn't copy-paste UVs accurately, I had to move every face into position in the UV editor by hand.

The final model looked like this:


This is obviously no great work of art, but the point was to take a crash-course in UV layout, not make something beautiful. That it took me three hours to lay out what you see above, however, seems quite wrong to me. I know UV layout is a non-trivial process, but seriously? It's a fucking crate, a glorified cube. Seems like this should've taken fifteen minutes tops.

My major stumbling blocks right now are these:

  • Having to convert selections to UVs seems wrong. Why can't I just select a face, or a group of faces, and manipulate them in the UV editor directly?
  • Having to cut and sew UVs also seems wrong, at least for this kind of application. I want to say, "This geometry uses this part of the texture," and not have that impact the UV mapping for other parts of the model.
  • Cutting UVs seems inconsistent. Sometimes it just doesn't do anything, and my UVs are still connected to stuff I don't want.
  • Repeating the exact same steps for each individual face, where the whole set of faces was to share the exact same part of the texture, seems unnecessary. I feel like I should be able to select the whole group of faces and map them all at once.
  • The UV editor display seems very awkward. It doesn't isolate selections properly, and if I use the "View contained faces" or "View connected faces" options, I can't make selections without Maya automatically reverting the view settings at the same time. Leaving everything displayed is confusing as hell, though.

All that being said, this is not a rant against Maya. Hundreds of thousands of artists the world over use these UV mapping tools every day, and make amazing stuff. I have to believe I'm simply approaching this process all wrong. None of the tutorials I found did a good job explaining technique; they only dealt with how to operate the tools, not so much how to effectively use them.

So, if there are any artists reading this... any tips? 'Cause I'm pretty discouraged right now, but I know there's a right way to do this. How long would that crate have taken you to unwrap?

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