# Incorporate ZOGY and A&L decorrelation option into imageDifference.py

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#### Details

• Type: Epic
• Status: Done
• Resolution: Done
• Fix Version/s: None
• Component/s:
• Labels:
None
• Epic Name:
Incorporate ZOGY and A&L decorrelation option into imageDifference.py
• Story Points:
40
• Sprint:
• WBS:
02C.03.04
• Team:
• Cycle:
Fall 2017

#### Description

Incorporate ZOGY and A&L decorrelation option into imageDifference.py. This is specifically regarding the spatially-varying variants of each, which rely upon the ImageMapReduce tasks. This epic includes fixing various bugs discovered after incorporation into imageDifference.py and running them on real images.

#### Stories in Epic (Custom Issue Matrix)

Key Summary Story Points Assignee Status

DM-10805 8 David Reiss Done

DM-10804 4 David Reiss Done

DM-10803 4 David Reiss Done

DM-10009 2 David Reiss Done

DM-11813 12 David Reiss Done

DM-11951 6 David Reiss Done

#### Activity

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David Reiss added a comment - - edited

Need to update ImageMapReduce to return 2 exposures (diffim and matched template, used for dipole fitting). This is currently not implemented (for spatially Zogy) but I added a check in imageDifference.py so that if it doesn't exist in the returned Struct, then it is not used.

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David Reiss added a comment - - edited Need to update ImageMapReduce to return 2 exposures (diffim and matched template, used for dipole fitting). This is currently not implemented (for spatially Zogy) but I added a check in imageDifference.py so that if it doesn't exist in the returned Struct, then it is not used.
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David Reiss added a comment - - edited

Zogy has been integrated into imageDifference.py in this ticket. The means of integration is not ideal, I admit, but this is due to the current organization of the imageDifference.py ImageDifferenceTask.run method itself. I decided not to refactor that method here, as that is subject to another ticket (DM-5295and DM-3704). After this ticket is merged, I will prioritize DM-5295 and DM-3704 to facilitate further improvements to the image differencing task.

Both the constant-across-the-image and the spatially-varying versions of Zogy are available. By default the constant one is enabled (config doSpatiallyVarying=False), but after further testing this default could be changed.

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David Reiss added a comment - - edited Zogy has been integrated into imageDifference.py in this ticket. The means of integration is not ideal, I admit, but this is due to the current organization of the imageDifference.py ImageDifferenceTask.run method itself. I decided not to refactor that method here, as that is subject to another ticket ( DM-5295 and DM-3704 ). After this ticket is merged, I will prioritize DM-5295 and DM-3704 to facilitate further improvements to the image differencing task. Both the constant-across-the-image and the spatially-varying versions of Zogy are available. By default the constant one is enabled (config doSpatiallyVarying=False), but after further testing this default could be changed.
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David Reiss added a comment - - edited

For some reason, measurement is very slow when using the spatiallyVarying (ALdecorrelation and Zogy) options.
Possibly due to use of the CoaddPsf for those resulting diffims. To be evaluated in DM-10806.

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David Reiss added a comment - - edited For some reason, measurement is very slow when using the spatiallyVarying (ALdecorrelation and Zogy) options. Possibly due to use of the CoaddPsf for those resulting diffims. To be evaluated in DM-10806 .
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David Reiss added a comment - - edited

Another issue identified: Zogy seems to lead to slightly too many positive (~20%) and way too many (~2x) negative detections. Need to investigate this. It is partly due to the artifacts around bright stars (see comment below) but also seen in vicinity of image edges.

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David Reiss added a comment - - edited Another issue identified: Zogy seems to lead to slightly too many positive (~20%) and way too many (~2x) negative detections. Need to investigate this. It is partly due to the artifacts around bright stars (see comment below) but also seen in vicinity of image edges.
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David Reiss added a comment -

Zogy diffim's have strange "fingerprint"-like artifacts around bright (but unsaturated) stars. Possibly a result of the sinc interpolation used for warping. This needs to be investigated.

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David Reiss added a comment - Zogy diffim's have strange "fingerprint"-like artifacts around bright (but unsaturated) stars. Possibly a result of the sinc interpolation used for warping. This needs to be investigated.

#### People

Assignee:
David Reiss
Reporter:
David Reiss
Watchers:
David Reiss