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Using GIMP 2.8. Trying to map an image to a sphere. The idea is to make custom Christmas balls. In addition to map to sphere, I have tried perspective and cage transform, but with limited success.

enter image description here

For images that are centered on the ball, I have made progress by doing a perspective shift on one half of the image using the grid for measuring, then an identical shift on the other half.

For images on the sides of the balls, I have used perspective and cage transform, then cropped to the radius, but it all looks rather janky. I am getting somewhere with map to sphere, but controlling the radius and warpage is a huge problem.

Here is the final product I am aiming to create:

enter image description here

Help appreciated soon, Need better image by December 2016, Thanx, Steve

  • Map to Sphere would be the way to go - which of your examples was made that way? – Michael Schumacher Nov 23 '16 at 16:06
  • Offtopic: Using a logo inside a chrismass sphere is ok. But puting a logo inside another logo, please... do not do that! – Rafael Nov 23 '16 at 17:40
  • Sorry about the logo-in-logo. I'm not fond of it either. I spent months making these three logos and the temptation to combine them overwhelmed me. Something about being the top of the Christmas tree...... – JSMe Nov 25 '16 at 17:37
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Map to sphere is fairly straightforward, the whole width of the image is mapped to the equator and the height is mapped to a meridian, so if you do not want your object to cover the whole sphere you need to add margins. A square image produces a sphere, and since the width of the image is mapped to the double of the height and everything looks stretched 2x horizontally, so you have to shrink horizontally (or strech vertically) first.

enter image description here

  • The result looks very good, but in my opinion the process using Gimp needs to be a bit more clear. n_n I also think you are using blending modes or something. – Rafael Nov 23 '16 at 17:38
  • Nope, just horizontal shrink and plain unadulterated Map Object/Sphere with about all defaults except a bit of orientation. – xenoid Nov 23 '16 at 20:53
  • so: start with a rectangle that is 1 unit high by 2 units wide, place your art, then resize the image to 1 unit high by 1 unit wide (alter aspect ratio), then apply the map-to-sphere? – Yorik Nov 23 '16 at 21:50
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    @Yorik Yes, thats a way to do it. – xenoid Nov 24 '16 at 0:57
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I probably am sumarizing what others already sayed.

Use Filter > Map > Map to sphere.

Gimp is simulating a spherical projection. This is a type of projection that starts from an image with proportions 2:1

enter image description here

But in the case of Gimp the implementation asumes that you also wants the proportion of the image you loaded.

So will give you back a spheroid.

enter image description here

To compensate this, resize your original artboard from the proportion 2:1 to a square.

enter image description here

And you will get a sphere. Or use the artboard at the 2:1 proportion and resize the spheroid.

enter image description here

Take a look at this paper to understand why the 2:1 proportion on the spherical projection. http://www.otake.com.mx/Apuntes/Imagen/EnviromentMaps/

  • I so appreciate the flurry of responses. I had not known about the 2:1 ratio, but looking at a globe vs. a flat earth map so makes the issue obvious. Duhhh!! First try got good results. Will keep playing today and post the results. – JSMe Nov 25 '16 at 17:32
  • Think I got the hang of it – JSMe Nov 26 '16 at 9:40

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