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I am currently doing a research on projection on a sphere, specifically for NOAA's project Science on a Sphere. What I'm trying to do is to find out how exactly do you create a video material for such a device, because it's not as simple as making a regular video since the projection on the sphere warps the final image a lot etc.

However, I'm struggling with finding any reasonable material source. I only found NOAA's creation guidelines, and even though they do describe all the problems with warping and having a seamless video pretty well, they do not describe specific methods, or the whole process of creating this kind of a video. They only mention several programs and plugins for Adobe's AE, but that's it.

Link: http://sos.noaa.gov/_downloads/docs/sos-content-creation-guidelines.pdf

I can't get any reasonable source from Google either, since all links are directing me to topics related to projecting a sphere (Earth) onto a plane, which is not what I'm trying to find at all.

I decided to give this site a shot and ask you whether you know any source/tutorial that could help me with this issue, or whether is here someone who understands this topic better than I do.

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  • $\begingroup$ If you solve it for still images, it ought to be the same solution for video frames right? Also just to make sure, you are just trying to avoid the distortion at the poles when naively putting a texture on a sphere? $\endgroup$ – Alan Wolfe Nov 26 '15 at 18:12
  • $\begingroup$ I believe you are correct with the still images. However, I wasnt able to find any good material about that either. And yes, I'm trying mainly to solve the distortion at poles problem, since the fact that left side has to be identical to right side of the video for a good transition is a trivial problem with easy solution. $\endgroup$ – Michal Kučera Nov 27 '15 at 14:32
  • $\begingroup$ Does this info help any? blender.stackexchange.com/questions/10741/… $\endgroup$ – Alan Wolfe Nov 27 '15 at 15:54
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You need to use a cylindrical projection. So the key issue is how to prepare data for a cylindrical projection. Basically what you do is:

  1. You project your data on a sphere, it may be that this process was already done for you.
  2. And then you project it back to a cylinder

Both steps can be easily taken care of by your cartography software. Will the data distort... yes but since you project information onto a sphere from whatever source onto a sphere and to cylindrical coordinates it will just interpolate the distortion away. If anything your just going to have slight over resolution at poles.

Quite a lot of data is in fact in this format to begin with. But nearly all 3D applications can use projected textures and texture baking to do these steps for you. Also most 2D applications like Photoshop have tools for turning rectangular coordinates to polar coordinates which do the same thing

The real question is what your original image data is like?

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