lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask Class Reference

Detect sources on a coadd. More...

Inheritance diagram for lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask:

Public Member Functions
def	__init__ (self, schema=None, kwargs)
	Initialize the task. More...
def	getInitOutputDatasets (self)
def	runDataRef (self, patchRef)
	Run detection on a coadd. More...
def	adaptArgsAndRun (self, inputData, inputDataIds, outputDataIds, butler)
def	run (self, exposure, idFactory, expId)
	Run detection on an exposure. More...
def	write (self, results, patchRef)
	Write out results from runDetection. More...

Public Attributes
	schema

Static Public Attributes
	ConfigClass = DetectCoaddSourcesConfig
	getSchemaCatalogs = _makeGetSchemaCatalogs("det")
	makeIdFactory = _makeMakeIdFactory("CoaddId")

Detailed Description

Detect sources on a coadd.

Contents

• Description
• Task initialization
• Invoking the Task
• Configuration parameters
• Debug variables
• A complete example

Description

Command-line task that detects sources on a coadd of exposures obtained with a single filter.

Coadding individual visits requires each exposure to be warped. This introduces covariance in the noise properties across pixels. Before detection, we correct the coadd variance by scaling the variance plane in the coadd to match the observed variance. This is an approximate approach – strictly, we should propagate the full covariance matrix – but it is simple and works well in practice.

After scaling the variance plane, we detect sources and generate footprints by delegating to the detection subtask.

Inputs:

deepCoadd{tract,patch,filter}: ExposureF

Outputs:

deepCoadd_det{tract,patch,filter}: SourceCatalog (only parent Footprints)
deepCoadd_calexp{tract,patch,filter}: Variance scaled, background-subtracted input exposure (ExposureF)
deepCoadd_calexp_background{tract,patch,filter}: BackgroundList

Data Unit:

tract, patch, filter

DetectCoaddSourcesTask delegates most of its work to the detection subtask. You can retarget this subtask if you wish.

Task initialization

Initialize the task. Create the detection subtask.

Keyword arguments (in addition to those forwarded to CmdLineTask.__init__):

Parameters

[in]	schema	initial schema for the output catalog, modified-in place to include all fields set by this task. If None, the source minimal schema will be used.
[in]	**kwargs	keyword arguments to be passed to lsst.pipe.base.task.Task.__init__

Invoking the Task

Run detection on an exposure. First scale the variance plane to match the observed variance using ScaleVarianceTask. Then invoke the detection subtask to detect sources.

Parameters

[in,out]	exposure	Exposure on which to detect (may be backround-subtracted and scaled, depending on configuration).
[in]	idFactory	IdFactory to set source identifiers
[in]	expId	Exposure identifier (integer) for RNG seed

Returns

a pipe.base.Struct with fields

• sources: catalog of detections
• backgrounds: list of backgrounds

Configuration parameters

See DetectSourcesConfig

Debug variables

The command line task interface supports a flag -d to import debug.py from your PYTHONPATH; see Using lsstDebug to control debugging output for more about debug.py files.

DetectCoaddSourcesTask has no debug variables of its own because it relegates all the work to SourceDetectionTask; see the documetation for SourceDetectionTask for further information.

A complete example

of using DetectCoaddSourcesTask

DetectCoaddSourcesTask is meant to be run after assembling a coadded image in a given band. The purpose of the task is to update the background, detect all sources in a single band and generate a set of parent footprints. Subsequent tasks in the multi-band processing procedure will merge sources across bands and, eventually, perform forced photometry. Command-line usage of DetectCoaddSourcesTask expects a data reference to the coadd to be processed. A list of the available optional arguments can be obtained by calling detectCoaddSources.py with the --help command line argument:

detectCoaddSources.py --help

To demonstrate usage of the DetectCoaddSourcesTask in the larger context of multi-band processing, we will process HSC data in the ci_hsc package. Assuming one has followed steps 1 - 4 at pipeTasks_multiBand, one may detect all the sources in each coadd as follows:

detectCoaddSources.py $CI_HSC_DIR/DATA --id patch=5,4 tract=0 filter=HSC-I

that will process the HSC-I band data. The results are written to $CI_HSC_DIR/DATA/deepCoadd-results/HSC-I.

It is also necessary to run:

detectCoaddSources.py $CI_HSC_DIR/DATA --id patch=5,4 tract=0 filter=HSC-R

to generate the sources catalogs for the HSC-R band required by the next step in the multi-band processing procedure: MergeDetectionsTask.

Definition at line 144 of file multiBand.py.

Constructor & Destructor Documentation

__init__()

def lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask.__init__	(		self,
			schema = None,
			kwargs
	)

Initialize the task.

Create the detection subtask.

Keyword arguments (in addition to those forwarded to CmdLineTask.__init__):

Parameters

[in]	schema	initial schema for the output catalog, modified-in place to include all fields set by this task. If None, the source minimal schema will be used.
[in]	**kwargs	keyword arguments to be passed to lsst.pipe.base.task.Task.__init__

Definition at line 247 of file multiBand.py.

    def __init__(self, schema=None, **kwargs):
        """!
        @brief Initialize the task. Create the @ref SourceDetectionTask_ "detection" subtask.

        Keyword arguments (in addition to those forwarded to CmdLineTask.__init__):

        @param[in] schema:   initial schema for the output catalog, modified-in place to include all
                             fields set by this task.  If None, the source minimal schema will be used.
        @param[in] **kwargs: keyword arguments to be passed to lsst.pipe.base.task.Task.__init__
        """
        # N.B. Super is used here to handle the multiple inheritance of PipelineTasks, the init tree
        # call structure has been reviewed carefully to be sure super will work as intended.
        super().__init__(**kwargs)
        if schema is None:
            schema = afwTable.SourceTable.makeMinimalSchema()
        if self.config.doInsertFakes:
            self.makeSubtask("insertFakes")
        self.schema = schema
        self.makeSubtask("detection", schema=self.schema)
        if self.config.doScaleVariance:
            self.makeSubtask("scaleVariance")

Member Function Documentation

adaptArgsAndRun()

def lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask.adaptArgsAndRun	(		self,
			inputData,
			inputDataIds,
			outputDataIds,
			butler
	)

Definition at line 290 of file multiBand.py.

    def adaptArgsAndRun(self, inputData, inputDataIds, outputDataIds, butler):
        packedId, maxBits = butler.registry.packDataId("tract_patch_abstract_filter",
                                                       inputDataIds["exposure"],
                                                       returnMaxBits=True)
        inputData["idFactory"] = afwTable.IdFactory.makeSource(packedId, 64 - maxBits)
        inputData["expId"] = packedId
        return self.run(**inputData)

getInitOutputDatasets()

def lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask.getInitOutputDatasets

(

self

)

Definition at line 269 of file multiBand.py.

    def getInitOutputDatasets(self):
        return {"detectionSchema": afwTable.SourceCatalog(self.schema)}

run()

def lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask.run	(		self,
			exposure,
			idFactory,
			expId
	)

Run detection on an exposure.

First scale the variance plane to match the observed variance using ScaleVarianceTask. Then invoke the detection subtask to detect sources.

Parameters

[in,out]	exposure	Exposure on which to detect (may be backround-subtracted and scaled, depending on configuration).
[in]	idFactory	IdFactory to set source identifiers
[in]	expId	Exposure identifier (integer) for RNG seed

Returns

a pipe.base.Struct with fields

• sources: catalog of detections
• backgrounds: list of backgrounds

Definition at line 298 of file multiBand.py.

    def run(self, exposure, idFactory, expId):
        """!
        @brief Run detection on an exposure.

        First scale the variance plane to match the observed variance
        using @ref ScaleVarianceTask. Then invoke the @ref SourceDetectionTask_ "detection" subtask to
        detect sources.

        @param[in,out] exposure: Exposure on which to detect (may be backround-subtracted and scaled,
                                 depending on configuration).
        @param[in] idFactory: IdFactory to set source identifiers
        @param[in] expId: Exposure identifier (integer) for RNG seed

        @return a pipe.base.Struct with fields
        - sources: catalog of detections
        - backgrounds: list of backgrounds
        """
        if self.config.doScaleVariance:
            varScale = self.scaleVariance.run(exposure.maskedImage)
            exposure.getMetadata().add("variance_scale", varScale)
        backgrounds = afwMath.BackgroundList()
        if self.config.doInsertFakes:
            self.insertFakes.run(exposure, background=backgrounds)
        table = afwTable.SourceTable.make(self.schema, idFactory)
        detections = self.detection.makeSourceCatalog(table, exposure, expId=expId)
        sources = detections.sources
        fpSets = detections.fpSets
        if hasattr(fpSets, "background") and fpSets.background:
            for bg in fpSets.background:
                backgrounds.append(bg)
        return Struct(outputSources=sources, outputBackgrounds=backgrounds, outputExposure=exposure)

runDataRef()

def lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask.runDataRef	(		self,
			patchRef
	)

Run detection on a coadd.

Invokes run and then uses write to output the results.

Parameters

[in]

patchRef

data reference for patch

Definition at line 272 of file multiBand.py.

    def runDataRef(self, patchRef):
        """!
        @brief Run detection on a coadd.

        Invokes @ref run and then uses @ref write to output the
        results.

        @param[in] patchRef: data reference for patch
        """
        if self.config.hasFakes:
            exposure = patchRef.get("fakes_" + self.config.coaddName + "Coadd", immediate=True)
        else:
            exposure = patchRef.get(self.config.coaddName + "Coadd", immediate=True)
        expId = int(patchRef.get(self.config.coaddName + "CoaddId"))
        results = self.run(exposure, self.makeIdFactory(patchRef), expId=expId)
        self.write(results, patchRef)
        return results

write()

def lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask.write	(		self,
			results,
			patchRef
	)

Write out results from runDetection.

Parameters

[in]	exposure	Exposure to write out
[in]	results	Struct returned from runDetection
[in]	patchRef	data reference for patch

Definition at line 330 of file multiBand.py.

    def write(self, results, patchRef):
        """!
        @brief Write out results from runDetection.

        @param[in] exposure: Exposure to write out
        @param[in] results: Struct returned from runDetection
        @param[in] patchRef: data reference for patch
        """
        coaddName = self.config.coaddName + "Coadd"
        patchRef.put(results.outputBackgrounds, coaddName + "_calexp_background")
        patchRef.put(results.outputSources, coaddName + "_det")
        if self.config.hasFakes:
            patchRef.put(results.outputExposure, "fakes_" + coaddName + "_calexp")
        else:
            patchRef.put(results.outputExposure, coaddName + "_calexp")

Member Data Documentation

ConfigClass

lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask.ConfigClass = DetectCoaddSourcesConfig

static

Definition at line 236 of file multiBand.py.

getSchemaCatalogs

lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask.getSchemaCatalogs = _makeGetSchemaCatalogs("det")

static

Definition at line 237 of file multiBand.py.

makeIdFactory

lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask.makeIdFactory = _makeMakeIdFactory("CoaddId")

static

Definition at line 238 of file multiBand.py.

schema

lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask.schema

Definition at line 264 of file multiBand.py.

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The documentation for this class was generated from the following file:

• /j/snowflake/release/lsstsw/stack/Linux64/pipe_tasks/18.1.0-11-gb2589d7b/python/lsst/pipe/tasks/multiBand.py