taskGNU Astronomy Utilities - Tasks: task #16273, Include non-linear warping in...


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task #16273: Include non-linear warping in absence of WCS

Submitter:  Raul Infante-Sainz <infantesainz>
Submitted:  Fri 07 Oct 2022 07:57:33 AM UTC
Should Start On:  Fri 07 Oct 2022 12:00:00 AM UTC Should be Finished on:  Fri 07 Oct 2022 12:00:00 AM UTC
Category:  Warp Priority:  5 - Normal
Item Group:  Enhancement Status:  None
Privacy:  Public Percent Complete:  0%
Assigned to:  None Open/Closed:  Open
Effort:  0.00

Fri 07 Oct 2022 12:05:36 PM UTC, comment #1: 

Thanks for adding the note here Raul.

Just to be more precise, during our suggestion, this suggestion came up: having something like '--center' in the linear warping also.

Basically, when the image has no WCS (or '--mode=img': we also need to add '--mode' to Warp), Warp will internally calculate the necessary linear translation so the given pixel coordinate of the input is in the center of the output image.

For example the 'centered.fits' file created below will be translated such that the coordinate (1.2,8.9) of the input image will be in the center of the central pixel of the output image.

$ astwarp img.fits --center=1.2,8.9 --mode=img --output=centered.fits

Combined with the '--width' and '--widthinpix' options, implementing this will make a similar interface to Crop. But in Warp it shifts pixel values as requested and will thus take longer.

Mohammad Akhlaghi <makhlaghi>
Group administrator
Fri 07 Oct 2022 07:57:33 AM UTC, original submission:  

Pedram and Mohammad did a wonderful job including the warping, distortion, etc. in Gnuastro. However, it is necessary to have WCS information to use them. If for any reason the image doesn't have WCS information, then high-level warping (non-linear transformation, distortion, etc.) are not available. In this case the user would have to make the warping manually (using the --translate and similar options).

This came up after a discussion, and to not forget to do this, I am defining this task. Thanks a lot for the great effort to all of you.

Raul Infante-Sainz <infantesainz>
Group Member


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