The current warp code works nicely, but it assumes that the interface is two Exposures (or (Image, Wcs) tuple) and warps one to the other.
Yasuda-san here at IPMU is looking at dipoles in his SNe difference imaging which uses the LSST ip_diffim code. The astrometry isn’t quite good enough, so he’d like to
- Solve for the relative astrometry between two coadds
- Warp one onto the other
Is there an easy way to do this? It could clearly be done by transforming the polynomial to a TAN-SIP Wcs, but that’s painful.
Looks like it’s impossible. I thought there was at least a way to warp an image via an
XYTransform (though we don’t have a polynomial
XYTransform at present), but even that doesn’t exist. It clearly should.
I agree this should be directly supported, but it is not. For now, I suggest the following hack:
- Create a plain TAN WCS (an instance of TanWcs with no distortion terms)
- Convert one to a DistortedTanWcs by adding the desired XYTransform
- You now have a pair of WCS that can be used to provide the desired transform
I filed https://jira.lsstcorp.org/browse/DM-4162