This is for use in hugin as an an autopano-sift-c wrapper, it does all the
usual autopano stuff except it does it on temporary stereographic versions of
the photos. This is all done behind the scenes so all you have to do is to
specify the projection type of your photos and an approximate field of view.
I'd recommend also using --finetune option as this is better done in
stereographic space in principle.
Only tested on fisheye images, rectilinear should work but has had no testing.