[task #15729] Warp on 3D cubes (at first 2D warp over third dimension)

[Mohammad Akhlaghi]

URL:
  <https://savannah.gnu.org/task/?15729>

                 Summary: Warp on 3D cubes (at first 2D warp over third
dimension)
                 Project: GNU Astronomy Utilities
            Submitted by: makhlaghi
            Submitted on: Thu 16 Jul 2020 09:05:59 PM BST
         Should Start On: Thu 16 Jul 2020 12:00:00 AM BST
   Should be Finished on: Thu 16 Jul 2020 12:00:00 AM BST
                Category: Warp
                Priority: 5 - Normal
              Item Group: Enhancement
                  Status: None
                 Privacy: Public
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                  Effort: 0.00

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Details:

Currently Warp only works on 2D images. But an increasingly large fraction of
astronomical data are being produced as 3D cubes, so it would be very useful
if Warp could also be used on them.

The main technical difficulty is that on a 2D surface, we have polygons that
can represent the pixels in the warped grid. But in 3D we would need 3D
polygons which are much more complex. 

However, one advantage with most (almost all, as far as I know!) cubes is that
their third dimension is independent of the first two by physical nature (the
first two are usually spatial dimensions: RA and Dec) and the third is
spectral. So very rarely will one want to do a warp that includes a mixing of
the first two, and third dimension.

So as a first step in this task, Warp can treat the 3D cube as independent 2D
images, do the warping on each, then stack them back into a 3D cube.




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