[AstroPy] Reprojecting each slice in a data cube based on another cube's WCS?

[Tim Jenness]

Not an astropy answer but the Starlink wcsalign command (part of kappa)
does this. You just give it your reference cube and the cubes you want
resampled and it works it all out.

http://www.starlink.ac.uk

Specifically http://www.starlink.ac.uk/docs/sun95.htx/node427.html

This is all done using the AST library so you can do it at a bit of a lower
level using pyast.

-- 
Tim Jenness


On Wed, May 8, 2013 at 12:58 PM, Eric L. N. Jensen
<ejensen1 at swarthmore.edu>wrote:

> Hi all,
>
> I'm working on a comparison of disk models to some ALMA synthesis imaging
> data, and in order to be able to compare models to data on a pixel-by-pixel
> basis, I'd like to be able to reproject each of the planes in a model data
> cube, based on the world coordinate system (WCS) information in the header
> of the observed data. I thought I might be able to do this with the python
> wrapper to Montage (using mProject), but it doesn't appear that mProject
> will handle 3D data (though I have posted a query to the Montage users'
> list as well to see if I'm missing something there).
>
> My files are FITS files with NAXIS = 3, where the first two axes are RA
> and Dec and the third axis is frequency or velocity, i.e. each slice of the
> third dimension is a 2-D image at a different frequency.
>
> The CRVAL/CDELT/CRPIX values of the third axis are already identical in
> both models and data, so no reprojection/resampling along the third axis is
> necessary - essentially I'm looking for an efficient way to spatially
> re-project each 2D image plane -  ideally without disassembling all the
> slices, reprojecting them individually, and reassembling them into a single
> file.
>
> I'm sure that python has various lower-level interpolation/resampling
> algorithms that I can use if necessary, but I'm hoping not to have to do
> the FITS header keyword parsing / recalculating / reprojecting work myself
> if this is already possible with existing high-level tools.  (The field of
> view is small, so it's really just a linear resampling problem, no
> complicated wide-field projection issues.)
>
> Thanks in advance for your help with this,
>
> Eric
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