Suppose that you have a projection obtained by mapping spherical coordinates to a texture; example:

enter image description here

  1. What is that projection called?

  2. Is it possible to "fix" such texture so that it becomes a regular perspective projection?


1 Answer 1

  1. That specific projection is called an equirectangular projection.

  2. Your second question is much harder to answer. The short answer is "no" there isn't a "simple" way to fix this projection to a perspective projection. You can easily map it to a cube, but that's just due to how it's defined (you can find out more about this with a quick google search). As for a more difficult answer, if you need to create a perspective image from one of these projections, you'll have to do some more advanced edge and line detection. I found paper that talks about some methods, but it's still quite tricky.

Face and Straight Line Detection in Equirectangular Images


After a bit more research, I found that you can make a perspective projection by projecting each point on the sphere onto a cube that contains the sphere. Paul Bourke has a quick tutorial for photoshop which can probably be converted to pseudocode fairly easily.

Paul Bourke - Spherical Panoramas

  • \$\begingroup\$ So your original answer about edge detections was wrong, right? That is really cool. You nailed it. Thank you very much! \$\endgroup\$
    – MaiaVictor
    Aug 16, 2016 at 12:23
  • \$\begingroup\$ Yeah, the edge detection paper was just about edge detection in spherical mapping systems. I believe Paul Bourke shows you how to just go from a spherical projection to perspective. \$\endgroup\$ Aug 16, 2016 at 12:34

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