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  1. Data Management
  2. DM-10189

Create translation operator

    Details

    • Type: Story
    • Status: Done
    • Resolution: Done
    • Fix Version/s: None
    • Component/s: meas_deblender
    • Labels:
      None

      Description

      One of the major flaws in the current deblender is that it assumes the peaks passed to the function are the correct peak locations for the center of each object. This is wrong in the sense that

      1. Sometimes the position is grossly incorrect, as the peak position can be off by as much as a pixel or two from the true peak
      2. Even when the peak position is close, the actual source is always at some fractional pixel position, so the symmetry constraint can fail to converge for sources offset by nearly half a pixel.

      Peter Melchior and I propose to implement a translation operator that will allow templates to be shifted by up to 2 pixels by rational numbers in x and y.

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            Hide
            fred3m Fred Moolekamp added a comment -

            Designing this feature took longer than expected, so the story points were increased and the ticket was modified from "Implement translation operator" to "create translation operator". DM-10310 was created to track implementing the operators and algorithm designed over the past two weeks into the NMF deblender.

            Show
            fred3m Fred Moolekamp added a comment - Designing this feature took longer than expected, so the story points were increased and the ticket was modified from "Implement translation operator" to "create translation operator". DM-10310 was created to track implementing the operators and algorithm designed over the past two weeks into the NMF deblender.
            Hide
            fred3m Fred Moolekamp added a comment -

            This ticket creates 3 operators: Tx, where S Tx shifts a flattened image S in the x-direction; Ty, where Ty S shifts a flattened image in the y-direction; and Txy, where Txy S shifts the flattened image S in the x and y directions. See the ipython notebook testTranslation.ipynb for examples of the operators acting on an array, image with a single non-zero pixel, a full image, and a psf.

            Each peak in a blend will have a sparse Txy operator for each band (so BxK total Txy matrices) used to calculate the likelihood of the SED and Intensity matrices, where the model is of the form A Txy P S, where A is the SED matrix and S is the intensity matrix.

            To update the shifts in the x and y directions respectively, it is easier to use A Ty P Tx S, which separates the x and y translation operators and makes it easier to calculate their derivatives, needed to calculate the gradient step in the likelihood evaluation.

            Show
            fred3m Fred Moolekamp added a comment - This ticket creates 3 operators: Tx , where S Tx shifts a flattened image S in the x-direction; Ty , where Ty S shifts a flattened image in the y-direction; and Txy , where Txy S shifts the flattened image S in the x and y directions. See the ipython notebook testTranslation.ipynb for examples of the operators acting on an array, image with a single non-zero pixel, a full image, and a psf. Each peak in a blend will have a sparse Txy operator for each band (so BxK total Txy matrices) used to calculate the likelihood of the SED and Intensity matrices, where the model is of the form A Txy P S , where A is the SED matrix and S is the intensity matrix. To update the shifts in the x and y directions respectively, it is easier to use A Ty P Tx S , which separates the x and y translation operators and makes it easier to calculate their derivatives, needed to calculate the gradient step in the likelihood evaluation.
            Hide
            fred3m Fred Moolekamp added a comment -

            Hi Peter, do you mind reviewing this ticket that creates the translation operators?

            Show
            fred3m Fred Moolekamp added a comment - Hi Peter, do you mind reviewing this ticket that creates the translation operators?
            Hide
            pmelchior Peter Melchior added a comment -

            Notebook shows that the translation operators work as expected.

            Show
            pmelchior Peter Melchior added a comment - Notebook shows that the translation operators work as expected.

              People

              • Assignee:
                fred3m Fred Moolekamp
                Reporter:
                fred3m Fred Moolekamp
                Reviewers:
                Peter Melchior
                Watchers:
                Fred Moolekamp, Peter Melchior
              • Votes:
                0 Vote for this issue
                Watchers:
                2 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved:

                  Summary Panel