taskGNU Astronomy Utilities - Tasks: task #13565, Add non-linear warpings.

 
 

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task #13565: Add non-linear warpings.

Submitted by:  Mohammad Akhlaghi <makhlaghi>
Submitted on:  Mon 20 Apr 2015 06:31:32 AM UTC  
 
Should Start On:  Sun 19 Apr 2015 03:00:00 PM UTC Should be Finished on:  Sun 19 Apr 2015 03:00:00 PM UTC
Category:  Warp Priority:  3 - Low
Item Group:  New feature Status:  Postponed
Privacy:  Public Percent Complete:  0%
Assigned to:  None Open/Closed:  Open
Effort:  0.00

Mon 16 Mar 2020 05:52:59 PM UTC, comment #3: 

By the way, another good program that can be a good reference are SWarp (source on Github) and SCAMP (source on Github). The good news is that both these programs are in C and they are very commonly used many astronomical projects.

Even though its in C, the problem is that all the good code in these software are locked inside of them. We need to study that code (as well as the other nice software mentioned before) and write this job in a modular C library format that is usable generally and without so many dependencies ;-).

Mohammad Akhlaghi <makhlaghi>
Project Administrator
Mon 16 Mar 2020 02:44:20 AM UTC, comment #2: 

Thanks for the nice review. Generally in astronomy data (the FITS standard), the World Coordinate System (WCS, Section 8 of that paper, see references in the first paragraph of that section) also has standards to define distortions.

Mohammad Akhlaghi <makhlaghi>
Project Administrator
Sun 15 Mar 2020 10:32:20 PM UTC, comment #1: 

This paper gives a very nice method to correct optical distortion, which can also fix the sky distortion problem. The Wikipedia page also suggest a similar way but its a bit complex. In all these methods there is the distortion coefficient(k) is required. Now this paper provides an analytical way to find the coefficient. But it's complex to implement(thoughts?). We can just ask the user to provide these coefficients based on their own calibrations.

 

For celestial coordinate mapping this Wikipedia section provides good transformations required. I think we might need to use and/or modify the `wcs' library for its implementation.

For weak lensing this paper seems to pose many challenges on its implementation, so we can let go of this for the time being.

Sachin Kumar Singh <sks_15>
Project Member
Mon 20 Apr 2015 06:31:32 AM UTC, original submission:  

Currently only homographic (linear) warpings are included. Allow for non-linear warpings for applications like correcting optical distortion, celestial coordinate mapping or weak lensing.

Mohammad Akhlaghi <makhlaghi>
Project Administrator

 

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