I have recently modelled a lego figure and wish to UV unwrap it. This has mostly been easy, as you would expect, however I am running into several problems, all of them being either distorted unwraps, or inconsistent unwraps.

The following is the top hole of a lego figure leg, the one I am having trouble with:

See the unwrap at the top left? It is obviously distorted.

The other hole, however, does not unwrap like this at all. It unwraps as a clean and proportionate circle, as I would expect.

Why is this happening? I am new to UV unwrapping, so if I am totally misunderstanding seams please feel free to let me know and point me in the right direction.

I am using UV unwrap. I have already:

  • Applied scale and rotation (though not to the object I used to cut the whole out from, it was a default sphere).
  • Removed doubles
  • Recalculated Normals

I would appreciate help with this particular issue, as well as any tips as far as UV unwrapping goes.

Thanks for reading.

The .blend file of the leg

  • $\begingroup$ How did you UV unwrap this? Did you use Smart UV Project? $\endgroup$ – RobotUnderscore Apr 24 '16 at 23:21
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    $\begingroup$ It is not very clear from the image what the shape of your object is like. Ca you post another shaded screenshot? Does your object have Ngon faces (faces with more than 4 edges)? That is generally undesirable and usually produces weird results when unwrapping. Strive for a quad dominant mesh topology, that is composed mainly of faces with four sides. $\endgroup$ – Duarte Farrajota Ramos Apr 25 '16 at 0:00
  • $\begingroup$ @RobotUnderscore Updated; I am using UV unwrap. $\endgroup$ – CAA14 Apr 25 '16 at 3:19
  • $\begingroup$ Did you mark seams yourself or use the default? $\endgroup$ – 360ueck Apr 25 '16 at 3:20
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    $\begingroup$ @DuarteFarrajotaRamos It is the top of a lego figure leg, however I will get another picture. Yes, it does have N-gons. I know it's not ideal, but the weird thing here is that a similar part of the mesh (another circle cut-out basically) unnwraps great, and it has N-gons around it as well. Thanks for the comment. $\endgroup$ – CAA14 Apr 25 '16 at 3:21

Instead of manually marking seams, use smart UV unwrap. Smart UV unwrap breaks the mesh into islands based on angle threshold. Since the lego leg has very nice geometry, the default angle limit of 66 degrees works well.

Lego leg

In UV editor, press U > "Smart UV Project".

  • $\begingroup$ I will definitely try this(heading into town, I will get to this when I return), however may I ask: Do you know why it was unwrapping that way? In case the picture wasn't clear, I had seams(for both holes) around the outer and inner parts of the circle, and I made sure it was all the way around. I had used solidify only the edges, hence mine had depth. $\endgroup$ – CAA14 Apr 25 '16 at 14:40
  • $\begingroup$ Alrighty so it is a lot cleaner using smart uv thank you. However I am still curious as to why my original seams were not working. $\endgroup$ – CAA14 Apr 25 '16 at 20:09
  • $\begingroup$ Don’t forget to set an island margin when unwrapping. You can then select and scale each oval to make a perfect circle if needed (When I added depth to my leg, the circles unwrapped as ovals). $\endgroup$ – 360ueck Apr 26 '16 at 16:38
  • $\begingroup$ As for why, it’s difficult to tell from the photo, but it looks as if there are more vertices in one part of the upper circle, compared to the rest of the circumference. I found depending on how I applied the solidify and boolean, made a big difference to the vertices around the circles, and consequently how it unwrapped. If you post the .blend, I could take a closer look. I'm curious as well. If you've already erased the seams, the .blend2 may have still have them (this is the file with your previous save). $\endgroup$ – 360ueck Apr 26 '16 at 17:05
  • $\begingroup$ Alrighty, I will see about uploading it. $\endgroup$ – CAA14 Apr 26 '16 at 17:18

The red dots in your picture are pins, you may have accidentally added pins while adding seams (P in UV editor adds pins). If you press Shift-P to select pinned in vertex select mode, you can see the pins and seams don't agree. Specifically, only a quarter of the vertices belonging to the upper circle are pinned.

In the UV editor, select everything and press alt-P to unpin the vertices. Then unwrap your mesh once again, the circles should appear smooth now.

  • $\begingroup$ Ah, good to know! I used regular unwrap, and it works well, but the face that had the circles in it is distorted. I am either going to use smart unwrap with island margin or just use project from view. Thank again! $\endgroup$ – CAA14 Apr 28 '16 at 15:16
  • $\begingroup$ Did the circles unwrap good for you? What arguments did you use in smart projection? They do not unwrap as circles with smart projection for me. $\endgroup$ – CAA14 Apr 28 '16 at 15:22
  • $\begingroup$ Yes, the top was more of an oval than a circle though, but just select it and scale on the y-axis. It actually unwrapped nicer without the seams. When you have very simple geometry, marking seams isn't necessary. I find when doing anything in blender, think about how many other people have done something similar. The more people, the less work you need to do. In smart un-wrap I set the margin as 0.5, area weight as 1 and left angle at 66. $\endgroup$ – 360ueck Apr 28 '16 at 23:15

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