taskGNU Astronomy Utilities - Tasks: task #15636, Warp image to a fixed center...


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task #15636: Warp image to a fixed center position, accounting for distortions

Submitted by:  Mohammad Akhlaghi <makhlaghi>
Submitted on:  Tue 12 May 2020 12:47:23 AM UTC  
Should Start On:  Mon 11 May 2020 11:00:00 PM UTC Should be Finished on:  Mon 11 May 2020 11:00:00 PM UTC
Category:  Warp Priority:  5 - Normal
Item Group:  Enhancement Status:  None
Privacy:  Public Percent Complete:  0%
Assigned to:  Sachin Kumar Singh <sks_15> Open/Closed:  Open
Effort:  0.00

Sun 17 May 2020 02:51:52 AM UTC, comment #1: 

The WCSLIB function linwarp() (which seems to be more general than diswarp()) may be useful for this task.

From the manual:

  • diswarp() computes various measures of the distortion over a specified range of coordinates.
  • linwarp() computes various measures of the distortion over a specified range of pixel coordinates. If all distortions are prior, then linwarp() uses diswarp().
Mohammad Akhlaghi <makhlaghi>
Project Administrator
Tue 12 May 2020 12:47:23 AM UTC, original submission:  

Assuming `image.fits' has a correct/accurate WCS, once this task is complete, the user will be able to call Warp like this:

astwarp image.fits --center=RA,DEC --width=W1,W2

The output image will have a width of W1 (degrees) in first WCS axis and W2 (degrees) in second WCS axis and the center of the central pixel will be at RA and Dec. In the meantime, the image will be aligned to the celestial coordinates (East to the left and North to the top) and all optical and spherical distortions will be corrected.

The distortions are very important for this task so it will also involve adding non-linear warps, especially as the image becomes wide such that optical and spherical distortions become significant.

Mohammad Akhlaghi <makhlaghi>
Project Administrator


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