How to define an intrinsic matrix for the perspective image?

[zitianlll]

As we know, a panorama is often captured by a fish-eye len and exists barrel distortion? I'd like to know what is the intrinsic matrix(fx,fy,cx,cy) of the generated perspective image from the panorama.

Thank a lot!

[fuenwang]

After stitching to equirectangular format from fisheye cameras, we can simply assume the pixels are projected to a sphere.
We just need to define a camera plane with given FoV, height, and width. Then intrinsic can be defined.
You can refer to this line. "K" is the intrinsic of perspective images.

https://github.com/fuenwang/Equirec2Perspec/blob/master/Equirec2Perspec.py#L49