# Spherize a picture, bad perspective on the junction when projected

I'm a software developer, so I don't understand very much about photography.

My approach is the next: I'm trying to take a panorama about sticky images, then I make it 2:1 with margins and spherize it to see it in a sphere texture with my software.

So, step by step, what I do is:

1.- I take a picture like this: https://upload.wikimedia.org/wikipedia/commons/c/cd/View_from_connors_hill_panorama.jpg

2.- Then what I do, is adding margines to make it 2:1, for instance:

3.- Then I go to Photoshop > Filter > Distortion > Spherize > +100% and I get:

which concerns me about the junction between the end and the beginning, but I proceed to put it inside my software on a texture:

some parts of the pictures are ok:

but the junction is really awkward:

I don't mean that the junction is not continued, I mean about the beginning and the end which are not "spherized"

am I wrong with the projections? am I choosing another kind of spherical ??

Thank you very much in advance for your time.

Regards.

Rafael.

• There is not another kind of spherical but one. Take a look at this article I wrote some time ago that explains a basic idea of the diferent projections: otake.com.mx/Apuntes/Imagen/EnviromentMaps I have the feeling the algorithm you are using is NOT spherical. Nov 13 '15 at 21:22
• Also, sometime ago, there was a simmilar bug on kerkythea's render engine. Take a look on that post: kerkythea.net/forum/viewtopic.php?f=1&t=5168 maybe that will help you to figure out a methodology to solve your bug. P.S. Do not use a photography, use a grid. Nov 13 '15 at 21:28
• This might be a good source for better test images. Nov 14 '15 at 2:22

To get a good spherical view, you have to cover the entire sphere. Your panorama doesn't have 360° coverage in yaw--you didn't shoot the whole circle all the way around. Having a panorama that's 2:1 isn't enough by itself to do this magic.

The 2:1 aspect ratio is merely the outcome of a 360°x180° (full spherical view) panorama that's been mapped to an equirectangular projection, where the longitude and latitude have been mapped to simple Cartesian (x,y) coordinates. What you're starting with is probably a non-360 cylindrical mapping.

You need to shoot and stitch more scene coverage in a panorama for it to work the way you're envisioning. You could maybe try and figure out what scene coverage you do have and find a way to limit to that coverage in your viewer, but you won't be able to spin all the way around. Or you could go back to your pano and remap it as an equirectangular, but you'll not only have black bars at the top and bottom, but also for the uncovered parts of the scene where your junction is.

See also: How are virtual tour photos taken?

• Also, there's no reason to use the spherize photoshop filter. That's for creating an effect, not for mapping to a panoshphere. Nov 14 '15 at 2:13
• Well, I think that's the point. Although I don't care about 360º coverage since I've said: > I don't mean that the junction is not continued, I mean about the beginning and the end which are not "spherized" < but the point is that I can get that strange junction because of it's not 360ºx180º. Also there's one error: as @junkyardsparkle says, I'm trying to "spherize" the map, but I'm not really looking for that, I'm looking for "despherize" it... which is not possible. Thank you very much guys for your help. Nov 16 '15 at 9:03