Can we get a fisheye to equirectangular implementation?

[cristianoccazinsp]

Just wondering how difficult it would be.

[BrianPugh]

I'm not looking to actively develop fisheye support, but would be open to PRs.

[ProGamerGov]

@BrianPugh I wonder if they mean something like option B (A sphere map that utilizes only 78% of the available texture
space and contains distorted areas (front)) in this image? Option C (Back-paraboloid environment map) is the only other fish eye option, but it omits one of the faces.

• Image from this paper: http://dx.doi.org/10.1007/978-3-642-10226-4_5

[ProGamerGov]

Option B seems like an old format originally designed for NVIDIA GeForce 256, which was the original release of the GeForce product line, and was released in 1999: https://www.hardware.fr/articles/53-8/cube-environment-map.html There's discovered this research paper on environment maps that mentions octahedral cubemaps in addition to the paraboloid ones: https://doi.org/10.6028/jres.122.025

I've got PyTorch code capable of producing option C:

Though the circular formats seem to be primarily used for small previews of 360 images or in older virtual environments.

I also came across this interesting format that is 2x3 set of faces:

https://naver.github.io/egjs-view360/docs/projections/cubemap

There are also different fisheye lenses used for dual fisheye cameras to produce 360 degree images.