Unity3D: Top and bottom portions of sphere are collapsing when a 360 image is set as its texture

I just learnt to put 360 photos on the inside of a sphere from here, but when I put any 360 photo, the top and bottom portions look like they are compressed, stitched and nailed on the poles :\

EDIT: Tried adding Cull Front to this script from an SO answer, but still I'm getting something like this

Is this the reason?

They seem to me as if only 720 or 1080 vertical pixels swept 360 degrees horizontally while missing the top and bottom portions (giving cylindrical and not spherical image). I just feel like a single pixel sweeping 360 degrees (when rotating along y-axis) would give a 1 pixel line, while this horizontal flat circle needs to sweep along x-axis to create a whole sphere. Correct me if I'm wrong

How do I apply a 360 panoramic picture to the inside of the sphere so that it looks like a complete virtual env? Or maybe I can't?

Solution

The image I chose was not equirectangular

I got more information and guidelines here

Prepare a suitable image The image to be used in the viewer must have a 2:1 aspect ratio and equirectangular projection, this means the top and bottom part of the image have to be stretched in order to render correctly inside the sphere

Solution:

Make sure you use an equirectangular image [top and bottom parts will be stretched]
Make a sphere and use an equirectangular shader [either invert the normals of the sphere or add Cull Front in the shader]
When the image is textured on the sphere, the progressive (literal pixel) compression towards the top and bottom of the sphere compensates the progressive stretching towards the top and bottom present in an equirectangular image