AssembleCoaddTask¶

class lsst.pipe.tasks.assembleCoadd.AssembleCoaddTask(*args, **kwargs)¶

Bases: lsst.pipe.tasks.coaddBase.CoaddBaseTask

Assemble a coadded image from a set of warps (coadded temporary exposures).

We want to assemble a coadded image from a set of Warps (also called coadded temporary exposures or coaddTempExps). Each input Warp covers a patch on the sky and corresponds to a single run/visit/exposure of the covered patch. We provide the task with a list of Warps (selectDataList) from which it selects Warps that cover the specified patch (pointed at by dataRef). Each Warp that goes into a coadd will typically have an independent photometric zero-point. Therefore, we must scale each Warp to set it to a common photometric zeropoint. WarpType may be one of ‘direct’ or ‘psfMatched’, and the boolean configs config.makeDirect and config.makePsfMatched set which of the warp types will be coadded. The coadd is computed as a mean with optional outlier rejection. Criteria for outlier rejection are set in AssembleCoaddConfig. Finally, Warps can have bad ‘NaN’ pixels which received no input from the source calExps. We interpolate over these bad (NaN) pixels.

AssembleCoaddTask uses several sub-tasks. These are

ScaleZeroPointTask
create and use an imageScaler object to scale the photometric zeropoint for each Warp
InterpImageTask
interpolate across bad pixels (NaN) in the final coadd

You can retarget these subtasks if you wish.

Notes

The lsst.pipe.base.CmdLineTask interface supports a flag -d to import debug.py from your PYTHONPATH; see baseDebug for more about debug.py files. AssembleCoaddTask has no debug variables of its own. Some of the subtasks may support debug variables. See the documentation for the subtasks for further information.

Examples

AssembleCoaddTask assembles a set of warped images into a coadded image. The AssembleCoaddTask can be invoked by running assembleCoadd.py with the flag ‘–legacyCoadd’. Usage of assembleCoadd.py expects two inputs: a data reference to the tract patch and filter to be coadded, and a list of Warps to attempt to coadd. These are specified using --id and --selectId, respectively:

--id = [KEY=VALUE1[^VALUE2[^VALUE3...] [KEY=VALUE1[^VALUE2[^VALUE3...] ...]]
--selectId [KEY=VALUE1[^VALUE2[^VALUE3...] [KEY=VALUE1[^VALUE2[^VALUE3...] ...]]

Only the Warps that cover the specified tract and patch will be coadded. A list of the available optional arguments can be obtained by calling assembleCoadd.py with the --help command line argument:

assembleCoadd.py --help

To demonstrate usage of the AssembleCoaddTask in the larger context of multi-band processing, we will generate the HSC-I & -R band coadds from HSC engineering test data provided in the ci_hsc package. To begin, assuming that the lsst stack has been already set up, we must set up the obs_subaru and ci_hsc packages. This defines the environment variable $CI_HSC_DIR and points at the location of the package. The raw HSC data live in the $CI_HSC_DIR/raw directory. To begin assembling the coadds, we must first

processCcd
process the individual ccds in $CI_HSC_RAW to produce calibrated exposures
makeSkyMap
create a skymap that covers the area of the sky present in the raw exposures
makeCoaddTempExp
warp the individual calibrated exposures to the tangent plane of the coadd

We can perform all of these steps by running

$CI_HSC_DIR scons warp-903986 warp-904014 warp-903990 warp-904010 warp-903988

This will produce warped exposures for each visit. To coadd the warped data, we call assembleCoadd.py as follows:

assembleCoadd.py --legacyCoadd $CI_HSC_DIR/DATA --id patch=5,4 tract=0 filter=HSC-I        --selectId visit=903986 ccd=16 --selectId visit=903986 ccd=22 --selectId visit=903986 ccd=23        --selectId visit=903986 ccd=100 --selectId visit=904014 ccd=1 --selectId visit=904014 ccd=6        --selectId visit=904014 ccd=12 --selectId visit=903990 ccd=18 --selectId visit=903990 ccd=25        --selectId visit=904010 ccd=4 --selectId visit=904010 ccd=10 --selectId visit=904010 ccd=100        --selectId visit=903988 ccd=16 --selectId visit=903988 ccd=17 --selectId visit=903988 ccd=23        --selectId visit=903988 ccd=24

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

You may also choose to run:

scons warp-903334 warp-903336 warp-903338 warp-903342 warp-903344 warp-903346
assembleCoadd.py --legacyCoadd $CI_HSC_DIR/DATA --id patch=5,4 tract=0 filter=HSC-R        --selectId visit=903334 ccd=16 --selectId visit=903334 ccd=22 --selectId visit=903334 ccd=23        --selectId visit=903334 ccd=100 --selectId visit=903336 ccd=17 --selectId visit=903336 ccd=24        --selectId visit=903338 ccd=18 --selectId visit=903338 ccd=25 --selectId visit=903342 ccd=4        --selectId visit=903342 ccd=10 --selectId visit=903342 ccd=100 --selectId visit=903344 ccd=0        --selectId visit=903344 ccd=5 --selectId visit=903344 ccd=11 --selectId visit=903346 ccd=1        --selectId visit=903346 ccd=6 --selectId visit=903346 ccd=12

to generate the coadd for the HSC-R band if you are interested in following multiBand Coadd processing as discussed in pipeTasks_multiBand (but note that normally, one would use the SafeClipAssembleCoaddTask rather than AssembleCoaddTask to make the coadd.

Attributes Summary

canMultiprocess

Methods Summary

`applyAltMaskPlanes`(mask, altMaskSpans)	Apply in place alt mask formatted as SpanSets to a mask.
`applyOverrides`(config)	A hook to allow a task to change the values of its config after the camera-specific overrides are loaded but before any command-line overrides are applied.
`assembleMetadata`(coaddExposure, …)	Set the metadata for the coadd.
`assembleSubregion`(coaddExposure, bbox, …)	Assemble the coadd for a sub-region.
`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.
`getBadPixelMask`()	!
`getCalExp`(dataRef, bgSubtracted)	!Return one “calexp” calibrated exposure
`getCoaddDatasetName`([warpType])	Return coadd name for given warpType and task config
`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.
`getSkyInfo`(patchRef)	!
`getTaskDict`()	Get a dictionary of all tasks as a shallow copy.
`getTempExpDatasetName`([warpType])	Return warp name for given warpType and task config
`getTempExpRefList`(patchRef, calExpRefList)	Generate list data references corresponding to warped exposures that lie within the patch to be coadded.
`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.
`makeSupplementaryData`(dataRef, selectDataList)	Make additional inputs to run() specific to subclasses.
`parseAndRun`([args, config, log, doReturnResults])	Parse an argument list and run the command.
`prepareInputs`(refList)	Prepare the input warps for coaddition by measuring the weight for each warp and the scaling for the photometric zero point.
`prepareStats`([mask])	Prepare the statistics for coadding images.
`processResults`(coaddExposure, dataRef)	Interpolate over missing data and mask bright stars.
`readBrightObjectMasks`(dataRef)	Retrieve the bright object masks.
`removeMaskPlanes`(maskedImage)	Unset the mask of an image for mask planes specified in the config.
`run`(skyInfo, tempExpRefList, …[, …])	Assemble a coadd from input warps
`runDataRef`(dataRef[, selectDataList])	Assemble a coadd from a set of Warps.
`selectExposures`(patchRef[, skyInfo, …])	!
`setBrightObjectMasks`(exposure, dataId, …)	Set the bright object masks.
`setInexactPsf`(mask)	Set INEXACT_PSF mask plane.
`setRejectedMaskMapping`(statsCtrl)	Map certain mask planes of the warps to new planes for the coadd.
`shrinkValidPolygons`(coaddInputs)	Shrink coaddInputs’ ccds’ ValidPolygons in place.
`timer`(name[, logLevel])	Context manager to log performance data for an arbitrary block of code.
`writeConfig`(butler[, clobber, doBackup])	Write the configuration used for processing the data, or check that an existing one is equal to the new one if present.
`writeMetadata`(dataRef)	Write the metadata produced from processing the data.
`writePackageVersions`(butler[, clobber, …])	Compare and write package versions.
`writeSchemas`(butler[, clobber, doBackup])	Write the schemas returned by `lsst.pipe.base.Task.getAllSchemaCatalogs`.

Attributes Documentation

canMultiprocess = True¶

Methods Documentation

applyAltMaskPlanes(mask, altMaskSpans)¶

Apply in place alt mask formatted as SpanSets to a mask.

Parameters:	mask : `lsst.afw.image.Mask` Original mask. altMaskSpans : `dict` SpanSet lists to apply. Each element contains the new mask plane name (e.g. “CLIPPED and/or “NO_DATA”) as the key, and list of SpanSets to apply to the mask.
Returns:	mask : `lsst.afw.image.Mask` Updated mask.

classmethod applyOverrides(config)¶

A hook to allow a task to change the values of its config after the camera-specific overrides are loaded but before any command-line overrides are applied.

Parameters:	config : instance of task’s `ConfigClass` Task configuration.

Notes

This is necessary in some cases because the camera-specific overrides may retarget subtasks, wiping out changes made in ConfigClass.setDefaults. See LSST Trac ticket #2282 for more discussion.

Warning

This is called by CmdLineTask.parseAndRun; other ways of constructing a config will not apply these overrides.

assembleMetadata(coaddExposure, tempExpRefList, weightList)¶

Set the metadata for the coadd.

This basic implementation sets the filter from the first input.

Parameters:	coaddExposure : `lsst.afw.image.Exposure` The target exposure for the coadd. tempExpRefList : `list` List of data references to tempExp. weightList : `list` List of weights.

assembleSubregion(coaddExposure, bbox, tempExpRefList, imageScalerList, weightList, altMaskList, statsFlags, statsCtrl, nImage=None)¶

Assemble the coadd for a sub-region.

For each coaddTempExp, check for (and swap in) an alternative mask if one is passed. Remove mask planes listed in config.removeMaskPlanes. Finally, stack the actual exposures using lsst.afw.math.statisticsStack with the statistic specified by statsFlags. Typically, the statsFlag will be one of lsst.afw.math.MEAN for a mean-stack or lsst.afw.math.MEANCLIP for outlier rejection using an N-sigma clipped mean where N and iterations are specified by statsCtrl. Assign the stacked subregion back to the coadd.

Parameters:

coaddExposure : lsst.afw.image.Exposure: The target exposure for the coadd.
bbox : lsst.afw.geom.Box: Sub-region to coadd.
tempExpRefList : list: List of data reference to tempExp.
imageScalerList : list: List of image scalers.
weightList : list: List of weights.
altMaskList : list: List of alternate masks to use rather than those stored with tempExp, or None. Each element is dict with keys = mask plane name to which to add the spans.
statsFlags : lsst.afw.math.Property: Property object for statistic for coadd.
statsCtrl : lsst.afw.math.StatisticsControl: Statistics control object for coadd.
nImage : lsst.afw.image.ImageU, optional: Keeps track of exposure count for each pixel.

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.

getBadPixelMask()¶: ! @brief Convenience method to provide the bitmask from the mask plane names

getCalExp(dataRef, bgSubtracted)¶

!Return one “calexp” calibrated exposure

@param[in] dataRef a sensor-level data reference @param[in] bgSubtracted return calexp with background subtracted? If False get the

calexp’s background background model and add it to the calexp.

@return calibrated exposure

If config.doApplyUberCal, meas_mosaic calibrations will be applied to the returned exposure using applyMosaicResults.

getCoaddDatasetName(warpType='direct')¶

Return coadd name for given warpType and task config

Parameters:	warpType : string Either ‘direct’ or ‘psfMatched’
Returns:	CoaddDatasetName : `string`

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.

See also

Task.getAllSchemaCatalogs

Notes

Warning

Subclasses that use schemas must override this method. The default implemenation returns an empty dict.

This method may be called at any time after the Task is constructed, which means that all task schemas should be computed at construction time, not when data is actually processed. This reflects the philosophy that the schema should not depend on the data.

Returning catalogs rather than just schemas allows us to save e.g. slots for SourceCatalog as well.

getSkyInfo(patchRef)¶

! @brief Use @ref getSkyinfo to return the skyMap, tract and patch information, wcs and the outer bbox of the patch.

@param[in] patchRef data reference for sky map. Must include keys “tract” and “patch”

@return pipe_base Struct containing: - skyMap: sky map - tractInfo: information for chosen tract of sky map - patchInfo: information about chosen patch of tract - wcs: WCS of tract - bbox: outer bbox of patch, as an afwGeom Box2I

getTaskDict()¶

Get a dictionary of all tasks as a shallow copy.

Returns:	taskDict : `dict` Dictionary containing full task name: task object for the top-level task and all subtasks, sub-subtasks, etc..

getTempExpDatasetName(warpType='direct')¶

Return warp name for given warpType and task config

Parameters:	warpType : string Either ‘direct’ or ‘psfMatched’
Returns:	WarpDatasetName : `string`

getTempExpRefList(patchRef, calExpRefList)¶

Generate list data references corresponding to warped exposures that lie within the patch to be coadded.

Parameters:	patchRef : `dataRef` Data reference for patch. calExpRefList : `list` List of data references for input calexps.
Returns:	tempExpRefList : `list` List of Warp/CoaddTempExp data references.

classmethod makeField(doc)¶

Make a lsst.pex.config.ConfigurableField for this task.

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

Examples

Provides a convenient way to specify this task is a subtask of another task.

Here is an example of use:

class OtherTaskConfig(lsst.pex.config.Config)
    aSubtask = ATaskClass.makeField("a brief description of what this task does")

makeSubtask(name, **keyArgs)¶

Create a subtask as a new instance as the name attribute of this task.

Parameters:	name : `str` Brief name of the subtask. keyArgs Extra keyword arguments used to construct the task. The following arguments are automatically provided and cannot be overridden: “config”. “parentTask”.

Notes

The subtask must be defined by Task.config.name, an instance of pex_config ConfigurableField or RegistryField.

makeSupplementaryData(dataRef, selectDataList)¶

Make additional inputs to run() specific to subclasses.

Available to be implemented by subclasses only if they need the coadd dataRef for performing preliminary processing before assembling the coadd.

Parameters:	dataRef : `lsst.daf.persistence.ButlerDataRef` Butler data reference for supplementary data. selectDataList : `list` List of data references to Warps.

classmethod parseAndRun(args=None, config=None, log=None, doReturnResults=False)¶

Parse an argument list and run the command.

Parameters:

args : list, optional: List of command-line arguments; if None use sys.argv.
config : lsst.pex.config.Config-type, optional: Config for task. If None use Task.ConfigClass.
log : lsst.log.Log-type, optional: Log. If None use the default log.
doReturnResults : bool, optional: If True, return the results of this task. Default is False. This is only intended for unit tests and similar use. It can easily exhaust memory (if the task returns enough data and you call it enough times) and it will fail when using multiprocessing if the returned data cannot be pickled.

Returns:

struct : lsst.pipe.base.Struct

Fields are:

argumentParser: the argument parser.
parsedCmd: the parsed command returned by the argument parser’s lsst.pipe.base.ArgumentParser.parse_args method.
taskRunner: the task runner used to run the task (an instance of Task.RunnerClass).
resultList: results returned by the task runner’s run method, one entry per invocation.

This will typically be a list of None unless doReturnResults is True; see Task.RunnerClass (TaskRunner by default) for more information.

Notes

Calling this method with no arguments specified is the standard way to run a command-line task from the command-line. For an example see pipe_tasks bin/makeSkyMap.py or almost any other file in that directory.

If one or more of the dataIds fails then this routine will exit (with a status giving the number of failed dataIds) rather than returning this struct; this behaviour can be overridden by specifying the --noExit command-line option.

prepareInputs(refList)¶

Prepare the input warps for coaddition by measuring the weight for each warp and the scaling for the photometric zero point.

Each Warp has its own photometric zeropoint and background variance. Before coadding these Warps together, compute a scale factor to normalize the photometric zeropoint and compute the weight for each Warp.

Parameters:	refList : `list` List of data references to tempExp
Returns:	result : `lsst.pipe.base.Struct` Result struct with components: `tempExprefList`: `list` of data references to tempExp. `weightList`: `list` of weightings. `imageScalerList`: `list` of image scalers.

prepareStats(mask=None)¶

Prepare the statistics for coadding images.

Parameters:	mask : `int`, optional Bit mask value to exclude from coaddition.
Returns:	stats : `lsst.pipe.base.Struct` Statistics structure with the following fields: `statsCtrl`: Statistics control object for coadd (`lsst.afw.math.StatisticsControl`) `statsFlags`: Statistic for coadd (`lsst.afw.math.Property`)

processResults(coaddExposure, dataRef)¶

Interpolate over missing data and mask bright stars.

Parameters:	coaddExposure : `lsst.afw.image.Exposure` The coadded exposure to process. dataRef : `lsst.daf.persistence.ButlerDataRef` Butler data reference for supplementary data.

readBrightObjectMasks(dataRef)¶

Retrieve the bright object masks.

Returns None on failure.

Parameters:	dataRef : `lsst.daf.persistence.butlerSubset.ButlerDataRef` A Butler dataRef.
Returns:	result : `lsst.daf.persistence.butlerSubset.ButlerDataRef` Bright object mask from the Butler object, or None if it cannot be retrieved.

removeMaskPlanes(maskedImage)¶

Unset the mask of an image for mask planes specified in the config.

Parameters:	maskedImage : `lsst.afw.image.MaskedImage` The masked image to be modified.

run(skyInfo, tempExpRefList, imageScalerList, weightList, altMaskList=None, mask=None, supplementaryData=None)¶

Assemble a coadd from input warps

Assemble the coadd using the provided list of coaddTempExps. Since the full coadd covers a patch (a large area), the assembly is performed over small areas on the image at a time in order to conserve memory usage. Iterate over subregions within the outer bbox of the patch using assembleSubregion to stack the corresponding subregions from the coaddTempExps with the statistic specified. Set the edge bits the coadd mask based on the weight map.

Parameters:

skyInfo : lsst.pipe.base.Struct: Struct with geometric information about the patch.
tempExpRefList : list: List of data references to Warps (previously called CoaddTempExps).
imageScalerList : list: List of image scalers.
weightList : list: List of weights
altMaskList : list, optional: List of alternate masks to use rather than those stored with tempExp.
mask : lsst.afw.image.Mask, optional: Mask to ignore when coadding
supplementaryData : lsst.pipe.base.Struct, optional: Struct with additional data products needed to assemble coadd. Only used by subclasses that implement makeSupplementaryData and override run.

Returns:

result : lsst.pipe.base.Struct

Result struct with components:

coaddExposure: coadded exposure (lsst.afw.image.Exposure).
nImage: exposure count image (lsst.afw.image.Image).

runDataRef(dataRef, selectDataList=[])¶

Assemble a coadd from a set of Warps.

Coadd a set of Warps. Compute weights to be applied to each Warp and find scalings to match the photometric zeropoint to a reference Warp. Assemble the Warps using run. Interpolate over NaNs and optionally write the coadd to disk. Return the coadded exposure.

Parameters:

dataRef : lsst.daf.persistence.butlerSubset.ButlerDataRef: Data reference defining the patch for coaddition and the reference Warp (if config.autoReference=False). Used to access the following data products: - self.config.coaddName + "Coadd_skyMap" - self.config.coaddName + "Coadd_ + <warpType> + "Warp" (optionally) - self.config.coaddName + "Coadd"
selectDataList : list: List of data references to Warps. Data to be coadded will be selected from this list based on overlap with the patch defined by dataRef.

Returns:

retStruct : lsst.pipe.base.Struct

Result struct with components:

coaddExposure: coadded exposure (Exposure).
nImage: exposure count image (Image).

selectExposures(patchRef, skyInfo=None, selectDataList=[])¶

! @brief Select exposures to coadd

Get the corners of the bbox supplied in skyInfo using @ref afwGeom.Box2D and convert the pixel positions of the bbox corners to sky coordinates using @ref skyInfo.wcs.pixelToSky. Use the @ref WcsSelectImagesTask_ “WcsSelectImagesTask” to select exposures that lie inside the patch indicated by the dataRef.

@param[in] patchRef data reference for sky map patch. Must include keys “tract”, “patch”,: plus the camera-specific filter key (e.g. “filter” or “band”)

@param[in] skyInfo geometry for the patch; output from getSkyInfo @return a list of science exposures to coadd, as butler data references

setBrightObjectMasks(exposure, dataId, brightObjectMasks)¶

Set the bright object masks.

Parameters:	exposure : `lsst.afw.image.Exposure` Exposure under consideration. dataId : `lsst.daf.persistence.dataId` Data identifier dict for patch. brightObjectMasks : `lsst.afw.table` Table of bright objects to mask.

setInexactPsf(mask)¶

Set INEXACT_PSF mask plane.

If any of the input images isn’t represented in the coadd (due to clipped pixels or chip gaps), the CoaddPsf will be inexact. Flag these pixels.

Parameters:	mask : `lsst.afw.image.Mask` Coadded exposure’s mask, modified in-place.

static setRejectedMaskMapping(statsCtrl)¶

Map certain mask planes of the warps to new planes for the coadd.

If a pixel is rejected due to a mask value other than EDGE, NO_DATA, or CLIPPED, set it to REJECTED on the coadd. If a pixel is rejected due to EDGE, set the coadd pixel to SENSOR_EDGE. If a pixel is rejected due to CLIPPED, set the coadd pixel to CLIPPED.

Parameters:	statsCtrl : `lsst.afw.math.StatisticsControl` Statistics control object for coadd
Returns:	maskMap : `list` of `tuple` of `int` A list of mappings of mask planes of the warped exposures to mask planes of the coadd.

shrinkValidPolygons(coaddInputs)¶

Shrink coaddInputs’ ccds’ ValidPolygons in place.

Either modify each ccd’s validPolygon in place, or if CoaddInputs does not have a validPolygon, create one from its bbox.

Parameters:	coaddInputs : `lsst.afw.image.coaddInputs` Original mask.

timer(name, logLevel=10000)¶

Context manager to log performance data for an arbitrary block of code.

Parameters:	name : `str` Name of code being timed; data will be logged using item name: `Start` and `End`. logLevel A `lsst.log` level constant.

Navigation

AssembleCoaddTask¶