bugGNU Astronomy Utilities - Bugs: bug #51353, Pure rotation must be around pixel...

 
 

You are not allowed to post comments on this tracker with your current authentication level.

bug #51353: Pure rotation must be around pixel coordinate (0,0)

Submitted by:  Mohammad Akhlaghi <makhlaghi>
Submitted on:  Sat 01 Jul 2017 12:54:49 PM UTC  
 
Category: WarpSeverity: 3 - Normal
Item Group: Output not reasonableStatus: Fixed
Privacy: PublicAssigned to: Mohammad Akhlaghi <makhlaghi>
Open/Closed: Closed

Sat 01 Jul 2017 01:25:16 PM UTC, comment #1:

The correction is now done and pushed to the main repo.

Mohammad Akhlaghi <makhlaghi>
Project AdministratorIn charge of this item.
Sat 01 Jul 2017 12:54:49 PM UTC, original submission:

When doing rotation about pixel coordinate (0,0) by an angle theta, until now Warp would use the following wrong equation (which is correct for rotation of the coordinates, not rotation of the point):

When rotating the point (not the coordinates), the negative sign changes. However, this was not noticed! The reason was that in the standard aligned images, the first axis (RA) of the WCS points to the left, not the right. So the rotation would actually occur not around image coordinate (0,0), but image coordinate (X,0), where X is the length of the image along the first axis.

This lead us to incorrectly associate rotation in the WCS axis directions (only when the RA and image X axis are in opposite directions).

The problem became clear when trying rotation on an image where the RA and X axis were in the same direction.

So the rotation matrix above is now corrected and like all the other warpings, rotation is also around the image coordinate (0,0). I am almost finished correcting it and will close this bug when it is complete.

Mohammad Akhlaghi <makhlaghi>
Project AdministratorIn charge of this item.

 

No files currently attached

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -unavailable- added by makhlaghi (Submitted the item)
  •  

    Do you think this task is very important?
    If so, you can click here to add your encouragement to it.
    This task has 0 encouragements so far.

    Only logged-in users can vote.

     

    Please enter the title of George Orwell's famous dystopian book (it's a date):

     

     

    Follow 2 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sat 01 Jul 2017 01:25:16 PM UTCmakhlaghiStatusIn Progress=>Fixed
      Open/ClosedOpen=>Closed

    Back to the top


    Powered by Savane 3.1-cleanup1