DRY: fslpy has some transform implementations

[effigies]

We should be checking to make sure that we're not duplicating effort over @pauldmccarthy's fsl.transform module. It includes implementations of FLIRT, FNIRT and X5.

https://git.fmrib.ox.ac.uk/fsl/fslpy/-/tree/master/fsl/transform

[pauldmccarthy]

Hey @effigies, unfortunately at this point in time I have too many other commitments to productively contribute to nitransforms. Most of the stuff I've added into fslpy has been to support FSL-specific workflows. The rendered documentation may give a more friendly overview: https://users.fmrib.ox.ac.uk/~paulmc/fsleyes/fslpy/latest/fsl.transform.html

As for the X5 stuff, it is very much a prototype. I haven't played a part in any of the X5 specification development - I knocked up this implementation just so that the FSL team would be ready to keep in line with wherever X5 goes (again from an FSL-specific standpoint).

But I'm more than happy for code to be migrated/donated from fslpy into nitransforms if you can see anything that might be of use to the wider community.

[effigies]

Sounds good. Thanks for what you've done so far, and we'll take what we need/can. We're working on a roadmap to upstream to nibabel, and will keep you up to date.

[oesteban]

Added a link where I believe fslpy could be the best reference. Please reopen if we need to have this around.