Best way to unwrap a sphere?

Support Materials and Textures
1

I’m trying to unwrap the default UV sphere to apply the following texture without stretching or overlapping.

UV_1k.jpg1000×1000 958 KB

I’ve just started learning about UV textures and mapping so this is all new to me.

Attachments

UV sphere.blend (1.52 MB)

2

Another approach is cubic mapping. Then you don’t have pole distortions at all. You could even start with a cube, and subdivide it until it is a sphere. A cast modifier may be a good idea afterwards then to make it really round.

But no matter what way, you will always have UV distortions in a spherical shape.

3

You can never have a UV texture for a curved surface without some stretching. Having said that, for a UV sphere, a straightforward way to minimise the stretching is to unwrap as gores (like an old-fashioned globe):

UV sphere.jpg1628×737 306 KB

Subsurfing complicates things. You should probably retopologise around the poles, as other posters have suggested (and use separate UV islands for them), and also turn off ‘Subdivide UVs’ in the Subsurf modifier.

Best wishes,
Matthew

4

As MCollett said, it’s just not possible. But understanding why it’s not possibleand trying the various ways that people have tried to solve the problem with a compromise in one aspect or another can lead to better understanding of topology and tessellation and how they interact.

Not using a UV sphere makes it a different problem. Icospheres unwrap without any distortion at all and polyspheres have a trivial amount, but it’s more diifficult to map the texture, especially if you are trying to use premade ones, like a map of the globe. If you plan to subsurf then the polysphere has no shading problems, followed by the UV sphere with poles patched with rectilinear grids.

5

Something that can help if you really need to unwrap an UV Sphere instead of using the subdivided plane warping is to change the poles topology.
Example a Sphere projection UV with a default UV sphere :

http://i.imgur.com/VQGskzw.jpg
VQGskzw.jpg396×659

As expected from an UV Sphere, the poles are badly distorted

But now, if you change the poles topology to something like that :

http://i.imgur.com/fIm32ig.jpg
fIm32ig.jpg456×627

Still a completely solid UV Sphere but the Sphere Projection UV will have made the poles really much better visually.
Only the very top of the pole will still be as expected distorted

1 Like
6

Thanks for the help guys.

7

Hi Sanctuary, I like this approach, but how do you change the poles topology? (I’m new to blender)

8

He added more loop cuts to the pole (ctrl+R) to make it smoother.

9

Take a cube, connect the vertex of one face forming a x, mark these and the “legs” as a seam and unwrap forming a large x in the uv sheet

Now we CA. Squeeze 2 points together on each ce center of the x a x make a a perfect square now subdivide the geometry and do to sphere

Except for mip mapping we have no seem

10

To make the top pole quads:

  1. Select the top vertex, Shift S; Cursor To Selected. Then delete the vertex to create a hole.
  2. Select the loop of verts and extrude. Cancel, Shift S; Selection To Cursor.

To manually unwrap:

  1. Select a quad and unwrap it.
  2. In UV editor, activate Snap To Pixels and Constrain To Image Bounds; move the UV vertices to the corners.
  3. With face still selected in 3D view, press L to select all, then UV Follow Active Quads.
  4. Select all UVs and scale them to fit your UV space (I tend to use the 2D cursor as origin, placed in lower left corner).

Alternatively, if you can leave a tiny hole at the poles (I prefer this as it survives the Remove Doubles command):

  1. Select all the top ring edges and subdivide them.
  2. Use gg (slide edge) on the new edge to i.e. 0.99 (or -0.99) and simply zoom in and delete the center vert.

For texture painting and deformability, I would probably use the Round Cube instead.