I've been trying to scale the UV map for a 3D arc (i.e. a slice of a hollow sphere) to fit the entire bounds of the UV map.

Unwrapping the mesh results in a circle, which I'm looking to scale up to the bounds of the map as in the following:

Initial Image

I played around with proportional editing - i.e. moved 4 diagonal vertices (top left, top right, etc) to the 4 corners using the sharp falloff, and then moved the 4 edge vertices (top, left, etc) to the 4 edges using the smooth falloff. But the best I could come up with was the following, which results in a really horribly warped map:

Final Image

If there's a better way to go about doing this (or a better way to use proportional editing correctly), I'd love to hear about it.

  • $\begingroup$ use lightmap pack option in unwrap menu but be aware that it separate the faces $\endgroup$
    – Chebhou
    Feb 14, 2015 at 10:52
  • $\begingroup$ making a square from a circle won't give you a good map. Usage of triangles won't help selecting loops... but you can select sides one by one (left, up, right, down), scale it to the good axis to 0 (left/right->X axis, up/down->Y axis) to make them flat, scale and move them to fit the borders. Then selecting all but borders, minimize stretch. $\endgroup$
    – Bithur
    Feb 14, 2015 at 10:56
  • $\begingroup$ You can using a Cast Modifier set to 'Cuboid' to reshape a duplicate of the model, UV map it and then transfer the UV's over to the sphere model using the new mesh transfer tools or with the Addon that is floating around somewhere. $\endgroup$ Feb 15, 2015 at 5:29

1 Answer 1


Select one side (left/right) from 1 diagonal to the other, only borders, and scale it on X axis to 0 (S, X, 0) then move it away
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Continue with other sides (up/down-> Y axis)
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Once all four sides scaled and moved away, select the other vertices, scale them down, then select the borders again
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scale and move them to fit your UV bounds enter image description here

Select everything but the border vertices and from the UV menu, click minimize stretch (or Ctrl+V)
enter image description here
use mouse wheel to blend the effect to your liking, when it's ok, hit enter
enter image description here


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