lsst.meas.base.forcedMeasurement.ForcedMeasurementTask Class Reference

A subtask for measuring the properties of sources on a single exposure, using an existing "reference" catalog to constrain some aspects of the measurement. More...

Inheritance diagram for lsst.meas.base.forcedMeasurement.ForcedMeasurementTask:

Public Member Functions
def	__init__
	Initialize the task. More...
def	run
	Perform forced measurement. More...
def	generateMeasCat
	Initialize an output SourceCatalog using information from the reference catalog. More...
def	attachTransformedFootprints
	Default implementation for attaching Footprints to blank sources prior to measurement. More...

Public Attributes
	mapper
	schema

Static Public Attributes
	ConfigClass = ForcedMeasurementConfig

Detailed Description

A subtask for measuring the properties of sources on a single exposure, using an existing "reference" catalog to constrain some aspects of the measurement.

The task is configured with a list of "plugins": each plugin defines the values it measures (i.e. the columns in a table it will fill) and conducts that measurement on each detected source (see ForcedPlugin). The job of the measurement task is to initialize the set of plugins (which includes setting up the catalog schema) from their configuration, and then invoke each plugin on each source.

Most of the time, ForcedMeasurementTask will be used via one of the subclasses of ForcedPhotImageTask, ForcedPhotCcdTask and ForcedPhotCoaddTask. These combine this measurement subtask with a "references" subtask (see BaseReferencesTask and CoaddSrcReferencesTask) to perform forced measurement using measurements performed on another image as the references. There is generally little reason to use ForcedMeasurementTask outside of one of these drivers, unless it is necessary to avoid using the Butler for I/O.

ForcedMeasurementTask has only three methods: init(), run(), and generateMeasCat(). For configuration options, see SingleFrameMeasurementConfig.

Definition at line 175 of file forcedMeasurement.py.

Constructor & Destructor Documentation

def lsst.meas.base.forcedMeasurement.ForcedMeasurementTask.__init__	(		self,
			refSchema,
			algMetadata = None,
			kwds
	)

Initialize the task.

Set up the execution order of the plugins and initialize the plugins, giving each plugin an opportunity to add its measurement fields to the output schema and to record information in the task metadata.

Note that while SingleFrameMeasurementTask is passed an initial Schema that is appended to in order to create the output Schema, ForcedMeasurementTask is initialized with the Schema of the reference catalog, from which a new Schema for the output catalog is created. Fields to be copied directly from the reference Schema are added before Plugin fields are added.

Parameters

[in]	refSchema	Schema of the reference catalog. Must match the catalog later passed to generateMeasCat() and/or run().
[in,out]	algMetadata	lsst.daf.base.PropertyList used to record information about each algorithm. An empty PropertyList will be created if None.
[in]	**kwds	Keyword arguments passed from lsst.pipe.base.Task.__init__

Definition at line 204 of file forcedMeasurement.py.

    def __init__(self, refSchema, algMetadata=None, **kwds):
        """!
        Initialize the task.  Set up the execution order of the plugins and initialize
        the plugins, giving each plugin an opportunity to add its measurement fields to
        the output schema and to record information in the task metadata.

        Note that while SingleFrameMeasurementTask is passed an initial Schema that is
        appended to in order to create the output Schema, ForcedMeasurementTask is
        initialized with the Schema of the reference catalog, from which a new Schema
        for the output catalog is created.  Fields to be copied directly from the
        reference Schema are added before Plugin fields are added.

        @param[in]  refSchema      Schema of the reference catalog.  Must match the catalog
                                   later passed to generateMeasCat() and/or run().
        @param[in,out] algMetadata lsst.daf.base.PropertyList used to record information about
                                   each algorithm.  An empty PropertyList will be created if None.
        @param[in]     **kwds      Keyword arguments passed from lsst.pipe.base.Task.__init__
        """
        super(ForcedMeasurementTask, self).__init__(algMetadata=algMetadata, **kwds)
        self.mapper = lsst.afw.table.SchemaMapper(refSchema)
        self.mapper.addMinimalSchema(lsst.afw.table.SourceTable.makeMinimalSchema())
        self.config.slots.setupSchema(self.mapper.editOutputSchema())
        for refName, targetName in self.config.copyColumns.items():
            refItem = refSchema.find(refName)
            self.mapper.addMapping(refItem.key, targetName)
        self.config.slots.setupSchema(self.mapper.editOutputSchema())
        self.initializePlugins(schemaMapper=self.mapper)
        self.schema = self.mapper.getOutputSchema()
        self.makeSubtask("applyApCorr", schema=self.schema)