Hello! I'd love it if this and mrcal could work together. Do you support mrcal .cameramodel files? If not, can you do that? Is your splined representation compatible with the mrcal splined stereographic model? If not, can it? Is your splined lens representation better in some way? If so, should mrcal use some of that logic? I didn't see any documentation about it. If you think the mrcal distribution methods could be improved, and are willing to help improve it, I would be very amenable. Let's collaborate to make both projects better!
I would love for us to move past the idea that non-pinhole projections have "distortion", and we should strive to remove this "distortion" by reprojecting stuff to pinhole models. In practice, ALL projections distort straight lines and/or shapes and/or sizes, so if you use the pinhole projection everywhere, your images look like crap (see iphone wide-lens camera output for instance). Most of the normal non-pinhole projection functions work fine for wide lenses, while behaving like a pinhole lens with long lenses: https://en.wikipedia.org/wiki/Fisheye_lens#Mapping_function
This is real clunky from a browser. https://caltopo.com can do this from a map (right-click on the viewpoint, point-info, simulated view). The horizonator (https://github.com/dkogan/horizonator/) is a hackable implementation; has a FAST local gui, and can easily be extended to do other stuff.