# Research: how to implement spatially varying PSF for spatially-varying ZOGY and AL(decorrelated)

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## Details

• Type: Story
• Status: Done
• Resolution: Done
• Fix Version/s: None
• Component/s:
• Labels:
None
• Story Points:
12
• Sprint:
• Team:

## Description

The ImageMapReduceTask can compute diffims for both ZOGY and A&L decorrelation, including a spatially-varying PSF and variance plane. However, it does not construct a usable spatially-varying PSF that is optimal for detection and measurement. This story will involve research on how to implement such an object (potentially a subclass of CoaddPsf) and implementing it and computing it flexibly for ImageMapReduceTask.

## Activity

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David Reiss added a comment -

Implemented as a CoaddPsf. Seems to work well.

Added to ImageMapReduceTask and now just needs some unit tests.

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David Reiss added a comment - Implemented as a CoaddPsf. Seems to work well. Added to ImageMapReduceTask and now just needs some unit tests.
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David Reiss added a comment -

We now construct (potentially) spatially-varying PSF via CoaddPsf, by default if the reduce operation is 'average' or 'sum'.
Added unit tests for all test cases that construct exposures via 'average' or 'sum'.
Rebased against latest master and tests pass.

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David Reiss added a comment - We now construct (potentially) spatially-varying PSF via CoaddPsf, by default if the reduce operation is 'average' or 'sum'. Added unit tests for all test cases that construct exposures via 'average' or 'sum'. Rebased against latest master and tests pass.
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David Reiss added a comment -

Ian, would you be able to review this ticket for me? A few minor changes scattered throughout, but the primary addition is in imageMapReduce (ImageReducerSubtask._constructPsf()), and corresponding unit test.

Thanks!

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David Reiss added a comment - Ian, would you be able to review this ticket for me? A few minor changes scattered throughout, but the primary addition is in imageMapReduce (ImageReducerSubtask._constructPsf()), and corresponding unit test. Thanks!
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David Reiss added a comment -
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David Reiss added a comment - Jenkins build successful: https://ci.lsst.codes/job/stack-os-matrix/22641/
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Ian Sullivan added a comment -

Looks good, I had only a few comments. Since I initiated the pull request, it looks like I can't mark it as 'approved' on GitHub, so in the future please create a pull request before sending a ticket for review.

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Ian Sullivan added a comment - Looks good, I had only a few comments. Since I initiated the pull request, it looks like I can't mark it as 'approved' on GitHub, so in the future please create a pull request before sending a ticket for review.
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David Reiss added a comment -

Passed CI (#22675), merging.

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David Reiss added a comment - Passed CI (#22675), merging.

## People

• Assignee:
David Reiss
Reporter:
David Reiss
Reviewers:
Ian Sullivan
Watchers:
David Reiss, Ian Sullivan