forcedPhotCoadd.py

Go to the documentation of this file.

#!/usr/bin/env python
#
# LSST Data Management System
# Copyright 2008-2015 AURA/LSST.
#
# This product includes software developed by the
# LSST Project (http://www.lsst.org/).
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the LSST License Statement and
# the GNU General Public License along with this program.  If not,
# see <https://www.lsstcorp.org/LegalNotices/>.
#
import lsst.pex.config
import lsst.pipe.base
import lsst.coadd.utils
import lsst.afw.table

from .forcedPhotImage import ProcessImageForcedConfig, ProcessImageForcedTask

__all__ = ("ForcedPhotCoaddConfig", "ForcedPhotCoaddTask")

class ForcedPhotCoaddConfig(ProcessImageForcedConfig):
    footprintDatasetName = lsst.pex.config.Field(
        doc = ("Dataset (without coadd prefix) that should be used to obtain (Heavy)Footprints for sources."
               "  Must have IDs that match those of the reference catalog."
               "  If None, Footprints will be generated by transforming the reference Footprints."),
        dtype = str,
        default = "meas",
        optional=True
    )

    def setDefaults(self):
        ProcessImageForcedTask.ConfigClass.setDefaults(self)
        self.references.removePatchOverlaps = False  # see validate() for why

    def validate(self):
        ProcessImageForcedTask.ConfigClass.validate(self)
        if (self.measurement.doReplaceWithNoise and self.footprintDatasetName is not None
            and self.references.removePatchOverlaps):
            raise ValueError("Cannot use removePatchOverlaps=True with deblended footprints, as parent "
                             "sources may be rejected while their children are not.")

## @addtogroup LSST_task_documentation
## @{
## @page processForcedCoaddTask
## ForcedPhotCoaddTask
## @copybrief ForcedPhotCoaddTask
## @}

class ForcedPhotCoaddTask(ProcessImageForcedTask):
    """!
    A command-line driver for performing forced measurement on coadd images

    This task is a subclass of ForcedPhotImageTask which is specifically for doing forced
    measurement on a coadd, using as a reference catalog detections which were made on overlapping
    coadds (i.e. in other bands).

    The run method (inherited from ForcedPhotImageTask) takes a lsst.daf.persistence.ButlerDataRef
    argument that corresponds to a coadd image.  This is used to provide all the inputs and outputs
    for the task:
     - A "*Coadd_src" (e.g. "deepCoadd_src") dataset is used as the reference catalog.  This not loaded
       directly from the passed dataRef, however; only the patch and tract are used, while the filter
       is set by the configuration for the references subtask (see CoaddSrcReferencesTask).
     - A "*Coadd_calexp" (e.g. "deepCoadd_calexp") dataset is used as the measurement image.  Note that
       this means that ProcessCoaddTask must be run on an image before ForcedPhotCoaddTask, in order
       to generate the "*Coadd_calexp" dataset.
     - A "*Coadd_forced_src" (e.g. "deepCoadd_forced_src") dataset will be written with the output
       measurement catalog.

    In addition to the run method, ForcedPhotCcdTask overrides several methods of ForcedPhotImageTask
    to specialize it for coadd processing, including makeIdFactory() and fetchReferences().  None of these
    should be called directly by the user, though it may be useful to override them further in subclasses.
    """

    ConfigClass = ForcedPhotCoaddConfig
    RunnerClass = lsst.pipe.base.ButlerInitializedTaskRunner
    _DefaultName = "forcedPhotCoadd"
    dataPrefix = "deepCoadd_"

    def getExposure(self, dataRef):
        name = self.config.coaddName + "Coadd_calexp_det"
        return dataRef.get(name) if dataRef.datasetExists(name) else None

    def makeIdFactory(self, dataRef):
        """Create an object that generates globally unique source IDs from per-CCD IDs and the CCD ID.

        @param dataRef       Data reference from butler.  The "CoaddId_bits" and "CoaddId"
                             datasets are accessed.  The data ID must have tract and patch keys.
        """
        # With the default configuration, this IdFactory doesn't do anything, because
        # the IDs it generates are immediately overwritten by the ID from the reference
        # catalog (since that's in config.copyColumns).  But we create one here anyway, to
        # allow us to revert back to the old behavior of generating new forced source IDs,
        # just by renaming the ID in config.copyColumns to "object_id".
        expBits = dataRef.get(self.config.coaddName + "CoaddId_bits")
        expId = long(dataRef.get(self.config.coaddName + "CoaddId"))
        return lsst.afw.table.IdFactory.makeSource(expId, 64 - expBits)

    def fetchReferences(self, dataRef, exposure):
        """Return an iterable of reference sources which overlap the exposure

        @param dataRef       Data reference from butler corresponding to the image to be measured;
                             should have tract, patch, and filter keys.
        @param exposure      lsst.afw.image.Exposure to be measured (not used by this implementation)

        All work is delegated to the references subtask; see CoaddSrcReferencesTask for information
        about the default behavior.
        """
        skyMap = dataRef.get(self.dataPrefix + "skyMap", immediate=True)
        tractInfo = skyMap[dataRef.dataId["tract"]]
        patch = tuple(int(v) for v in dataRef.dataId["patch"].split(","))
        patchInfo = tractInfo.getPatchInfo(patch)
        references = lsst.afw.table.SourceCatalog(self.references.schema)
        references.extend(self.references.fetchInPatches(dataRef, patchList=[patchInfo]))
        return references

    def attachFootprints(self, sources, refCat, exposure, refWcs, dataRef):
        """For coadd forced photometry, we use the deblended HeavyFootprints from the single-band
        measurements of the same band - because we've guaranteed that the peaks (and hence child sources)
        will be consistent across all bands before we get to measurement, this should yield reasonable
        deblending for most sources.  It's most likely limitation is that it will not provide good flux
        upper limits for sources that were not detected in this band but were blended with sources that
        were.
        """
        if self.config.footprintDatasetName is None:
            return ForcedPhotImageTask.attachFootprints(sources, refCat, exposure, refWcs, dataRef)
        self.log.info("Loading deblended footprints for sources from %s, %s" %
                      (self.config.footprintDatasetName, dataRef.dataId))
        fpCat = dataRef.get("%sCoadd_%s" % (self.config.coaddName, self.config.footprintDatasetName),
                            immediate=True)
        for refRecord, srcRecord in zip(refCat, sources):
            fpRecord = fpCat.find(refRecord.getId())
            if fpRecord is None:
                raise LookupError("Cannot find Footprint for source %s; please check that %sCoadd_%s"
                                  "IDs are compatible with reference source IDs" %
                                  (srcRecord.getId(), self.config.coaddName,
                                   self.config.footprintDatasetName))
            srcRecord.setFootprint(fpRecord.getFootprint())

    @classmethod
    def _makeArgumentParser(cls):
        parser = lsst.pipe.base.ArgumentParser(name=cls._DefaultName)
        parser.add_id_argument("--id", "deepCoadd_forced_src", help="data ID, with raw CCD keys + tract",
                               ContainerClass=lsst.coadd.utils.CoaddDataIdContainer)
        return parser