[task #15704] Assuming a default size for --wcsdistortion when no data included

[Mohammad Akhlaghi]

URL:
  <https://savannah.gnu.org/task/?15704>

                 Summary: Assuming a default size for --wcsdistortion when no
data included
                 Project: GNU Astronomy Utilities
            Submitted by: makhlaghi
            Submitted on: Tue 23 Jun 2020 03:07:46 AM BST
         Should Start On: Tue 23 Jun 2020 12:00:00 AM BST
   Should be Finished on: Tue 23 Jun 2020 12:00:00 AM BST
                Category: Fits
                Priority: 5 - Normal
              Item Group: Enhancement
                  Status: In Progress
                 Privacy: Public
        Percent Complete: 0%
             Assigned to: sks_15
             Open/Closed: Open
         Discussion Lock: Any
                  Effort: 0.00

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Details:

Currently, the Fits program's '--wcsdistortion' function can work on FITS HDUs
that don't have any data. But this is only the case for SIP --> TPV
conversion. The TPV --> SIP conversion needs an initial size for the dataset
and will crash without it.

Sachin, can you please look into the sip_tpv Python module and see what size
they assume when the input dataset is header-only (its NAXIS is 0)?

As a test file, I am sending an output of astrometry.net called
'sip-header.fits'. Its a FITS file with no data, but a single extension that
has an NAXIS=0. It is a standard FITS file and can be read into any library. 

The function that calls 'gal_wcs_distortion_convert' is
'keywords_distortion_wcs' function in bin/fits/keywords.c
<http://git.savannah.gnu.org/cgit/gnuastro.git/tree/bin/fits/keywords.c#n441>
(which is activated with the '--wcsdistortion' option is given to 'astfits').
You can simply give this image to 'astfits' in 'tests/developer-build.sh' and
set a default 'size_t *' array when there is no input dataset.

It is very important that we finish this very soon, so please do this before
continuing work on task #15700.



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File Attachments:


-------------------------------------------------------
Date: Tue 23 Jun 2020 03:07:46 AM BST  Name: sip-header.fits  Size: 11KiB  
By: makhlaghi

<http://savannah.gnu.org/task/download.php?file_id=49353>

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