PanoTools NG:
Re: Any way to specify arbitrary pole positions?
Erik Krause erik.krause@... 2015-May-19 18:18:08
Am 19.05.2015 um 00:51 schrieb #removed#:
> What I'm trying to do is project a spherical image to a different
> representation. Normally when you project from a sphere to
> equirectangular, the zenith is stretched across the top of the image
> and the nadir is stretched across the bottom. What I want to do is
> select two arbitrary points on the sphere to become stretched across
> the top and bottom of this new projection, and have the rest of the
> image distort as required. This would have the same effect as
> choosing arbitrary poles on a sphere and projecting to
> equirectangular, but you're right calling these "poles" is confusing
> because they're not opposite on the sphere.
I can not imagine what this should be good for. However, some thoughts:
Any point inside an equirectangular image can be the new pole. The other
pole will automatically be 180° away from this first pole, no matter
what you do.
If you choose two points not 180° apart and make them poles (which is
what you do if you stretch them across bottom and top of an equirect),
you'd need to stretch the area where the points are nearer to each other
and compress the area on the other side (a sphere is round, remember!).
This implies the distortion of all other areas. While this is feasible
it can't be done with any panotools based program. You'd need to figure
out the math for yourself, I can't, it's way beyond my scope. Eventually
you could use matlab to do something like that.
Anyway I'd be curious what you want to achieve...
--
Erik Krause
http://www.erik-krause.de
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Posted by: Erik Krause <#removed#>
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