PsfMatchTask¶

class lsst.ip.diffim.PsfMatchTask(*args, **kwargs)¶

Bases: lsst.pipe.base.Task

!

@brief Base class for Psf Matching; should not be called directly

@section ip_diffim_psfmatch_Contents Contents

@ref ip_diffim_psfmatch_Purpose

@ref ip_diffim_psfmatch_Initialize

@ref ip_diffim_psfmatch_IO

@ref ip_diffim_psfmatch_Config

@ref ip_diffim_psfmatch_Metadata

@ref ip_diffim_psfmatch_Debug

@ref ip_diffim_psfmatch_Example

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@section ip_diffim_psfmatch_Purpose Description

PsfMatchTask is a base class that implements the core functionality for matching the Psfs of two images using a spatially varying Psf-matching lsst.afw.math.LinearCombinationKernel. The Task requires the user to provide an instance of an lsst.afw.math.SpatialCellSet, filled with lsst.ip.diffim.KernelCandidate instances, and a list of lsst.afw.math.Kernels of basis shapes that will be used for the decomposition. If requested, the Task also performs background matching and returns the differential background model as an lsst.afw.math.Kernel.SpatialFunction.

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@ection ip_diffim_psfmatch_Initialize Task initialization

@copydoc __init__

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@section ip_diffim_psfmatch_IO Invoking the Task

As a base class, this Task is not directly invoked. However, run() methods that are implemented on derived classes will make use of the core _solve() functionality, which defines a sequence of lsst.afw.math.CandidateVisitor classes that iterate through the KernelCandidates, first building up a per-candidate solution and then building up a spatial model from the ensemble of candidates. Sigma clipping is performed using the mean and standard deviation of all kernel sums (to reject variable objects), on the per-candidate substamp diffim residuals (to indicate a bad choice of kernel basis shapes for that particular object), and on the substamp diffim residuals using the spatial kernel fit (to indicate a bad choice of spatial kernel order, or poor constraints on the spatial model). The _diagnostic() method logs information on the quality of the spatial fit, and also modifies the Task metadata.

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@section ip_diffim_psfmatch_Config Configuration parameters

See @ref PsfMatchConfig, @ref PsfMatchConfigAL, @ref PsfMatchConfigDF, and @ref DetectionConfig.

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@section ip_diffim_psfmatch_Metadata Quantities set in Metadata

<DL> <DT> spatialConditionNum <DD> Condition number of the spatial kernel fit;

via @link lsst.ip.diffim.PsfMatchTask._diagnostic PsfMatchTask._diagnostic @endlink </DD> </DT>

<DT> spatialKernelSum <DD> Kernel sum (10^{-0.4 * Δ zeropoint}) of the spatial Psf-matching kernel;: via @link lsst.ip.diffim.PsfMatchTask._diagnostic PsfMatchTask._diagnostic @endlink </DD> </DT>
<DT> ALBasisNGauss <DD> If using sum-of-Gaussian basis, the number of gaussians used;: via @link lsst.ip.diffim.makeKernelBasisList.generateAlardLuptonBasisList generateAlardLuptonBasisList@endlink </DD> </DT>
<DT> ALBasisDegGauss <DD> If using sum-of-Gaussian basis, the degree of spatial variation of the Gaussians;: via @link lsst.ip.diffim.makeKernelBasisList.generateAlardLuptonBasisList generateAlardLuptonBasisList@endlink </DD> </DT>
<DT> ALBasisSigGauss <DD> If using sum-of-Gaussian basis, the widths (sigma) of the Gaussians;: via @link lsst.ip.diffim.makeKernelBasisList.generateAlardLuptonBasisList generateAlardLuptonBasisList@endlink </DD> </DT>
<DT> ALKernelSize <DD> If using sum-of-Gaussian basis, the kernel size;: via @link lsst.ip.diffim.makeKernelBasisList.generateAlardLuptonBasisList generateAlardLuptonBasisList@endlink </DD> </DT>
<DT> NFalsePositivesTotal <DD> Total number of diaSources;: via @link lsst.ip.diffim.KernelCandidateQa.aggregate KernelCandidateQa.aggregate@endlink </DD> </DT>
<DT> NFalsePositivesRefAssociated <DD> Number of diaSources that associate with the reference catalog;: via @link lsst.ip.diffim.KernelCandidateQa.aggregate KernelCandidateQa.aggregate@endlink </DD> </DT>
<DT> NFalsePositivesRefAssociated <DD> Number of diaSources that associate with the source catalog;: via @link lsst.ip.diffim.KernelCandidateQa.aggregate KernelCandidateQa.aggregate@endlink </DD> </DT>
<DT> NFalsePositivesUnassociated <DD> Number of diaSources that are orphans;: via @link lsst.ip.diffim.KernelCandidateQa.aggregate KernelCandidateQa.aggregate@endlink </DD> </DT>
<DT> metric_MEAN <DD> Mean value of substamp diffim quality metrics across all KernelCandidates,: for both the per-candidate (LOCAL) and SPATIAL residuals; via @link lsst.ip.diffim.KernelCandidateQa.aggregate KernelCandidateQa.aggregate@endlink </DD> </DT>
<DT> metric_MEDIAN <DD> Median value of substamp diffim quality metrics across all KernelCandidates,: for both the per-candidate (LOCAL) and SPATIAL residuals; via @link lsst.ip.diffim.KernelCandidateQa.aggregate KernelCandidateQa.aggregate@endlink </DD> </DT>
<DT> metric_STDEV <DD> Standard deviation of substamp diffim quality metrics across all KernelCandidates,: for both the per-candidate (LOCAL) and SPATIAL residuals; via @link lsst.ip.diffim.KernelCandidateQa.aggregate KernelCandidateQa.aggregate@endlink </DD> </DT>

</DL>

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@section ip_diffim_psfmatch_Debug Debug variables

The @link lsst.pipe.base.cmdLineTask.CmdLineTask command line task@endlink interface supports a flag @c -d/–debug to import @b debug.py from your @c PYTHONPATH. The relevant contents of debug.py for this Task include:

@code{.py}

import sys import lsstDebug def DebugInfo(name):

di = lsstDebug.getInfo(name) if name == “lsst.ip.diffim.psfMatch”:

di.display = True # enable debug output di.maskTransparency = 80 # ds9 mask transparency di.displayCandidates = True # show all the candidates and residuals di.displayKernelBasis = False # show kernel basis functions di.displayKernelMosaic = True # show kernel realized across the image di.plotKernelSpatialModel = False # show coefficients of spatial model di.showBadCandidates = True # show the bad candidates (red) along with good (green)

return di

lsstDebug.Info = DebugInfo lsstDebug.frame = 1

@endcode

Note that if you want addional logging info, you may add to your scripts: @code{.py} import lsst.log.utils as logUtils logUtils.traceSetAt(“ip.diffim”, 4) @endcode

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@section ip_diffim_psfmatch_Example Example code

As a base class, there is no example code for PsfMatchTask. However, see @link lsst.ip.diffim.imagePsfMatch.ImagePsfMatchTask ImagePsfMatchTask@endlink, @link lsst.ip.diffim.snapPsfMatch.SnapPsfMatchTask SnapPsfMatchTask@endlink, and @link lsst.ip.diffim.modelPsfMatch.ModelPsfMatchTask ModelPsfMatchTask@endlink.

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Methods Summary

`emptyMetadata`()	Empty (clear) the metadata for this Task and all sub-Tasks.
`getAllSchemaCatalogs`()	Get schema catalogs for all tasks in the hierarchy, combining the results into a single dict.
`getFullMetadata`()	Get metadata for all tasks.
`getFullName`()	Get the task name as a hierarchical name including parent task names.
`getName`()	Get the name of the task.
`getSchemaCatalogs`()	Get the schemas generated by this task.
`getTaskDict`()	Get a dictionary of all tasks as a shallow copy.
`makeField`(doc)	Make a `lsst.pex.config.ConfigurableField` for this task.
`makeSubtask`(name, **keyArgs)	Create a subtask as a new instance as the `name` attribute of this task.
`timer`(name[, logLevel])	Context manager to log performance data for an arbitrary block of code.

Methods Documentation

emptyMetadata()¶: Empty (clear) the metadata for this Task and all sub-Tasks.

getAllSchemaCatalogs()¶

Get schema catalogs for all tasks in the hierarchy, combining the results into a single dict.

Returns:	schemacatalogs : `dict` Keys are butler dataset type, values are a empty catalog (an instance of the appropriate lsst.afw.table Catalog type) for all tasks in the hierarchy, from the top-level task down through all subtasks.

Notes

This method may be called on any task in the hierarchy; it will return the same answer, regardless.

The default implementation should always suffice. If your subtask uses schemas the override Task.getSchemaCatalogs, not this method.

getFullMetadata()¶

Get metadata for all tasks.

Returns:	metadata : `lsst.daf.base.PropertySet` The `PropertySet` keys are the full task name. Values are metadata for the top-level task and all subtasks, sub-subtasks, etc..

Notes

The returned metadata includes timing information (if @timer.timeMethod is used) and any metadata set by the task. The name of each item consists of the full task name with . replaced by :, followed by . and the name of the item, e.g.:

topLevelTaskName:subtaskName:subsubtaskName.itemName

using : in the full task name disambiguates the rare situation that a task has a subtask and a metadata item with the same name.

getFullName()¶

Get the task name as a hierarchical name including parent task names.

Returns:	fullName : `str` The full name consists of the name of the parent task and each subtask separated by periods. For example: The full name of top-level task “top” is simply “top”. The full name of subtask “sub” of top-level task “top” is “top.sub”. The full name of subtask “sub2” of subtask “sub” of top-level task “top” is “top.sub.sub2”.

getName()¶

Get the name of the task.

Returns:	taskName : `str` Name of the task.

Parameters:	doc : `str` Help text for the field.
Returns:	configurableField : `lsst.pex.config.ConfigurableField` A `ConfigurableField` for this task.

Navigation

PsfMatchTask¶