ForcedPeakCentroidPlugin¶

class lsst.meas.base.ForcedPeakCentroidPlugin(config, name, schemaMapper, metadata)¶

Bases: ForcedPlugin

Record the highest peak in a source footprint as its centroid.

This is of course a relatively poor measure of the true centroid of the object; this algorithm is provided mostly for testing and debugging.

This is similar to SingleFramePeakCentroidPlugin, except that transforms the peak coordinate from the original (reference) coordinate system to the coordinate system of the exposure being measured.

Parameters:

configForcedPeakCentroidConfig: Plugin configuraion.
namestr: Plugin name.
schemaMapperlsst.afw.table.SchemaMapper: A mapping from reference catalog fields to output catalog fields. Output fields are added to the output schema.
metadatalsst.daf.base.PropertySet: Plugin metadata that will be attached to the output catalog.

Attributes Summary

`APCORR_ORDER`	Order for algorithms which require shape, centroid and flux (`float`).
`CENTROID_ORDER`	Order for algorithms which require only Footprint and Peaks (`float`).
`DEFAULT_CATALOGCALCULATION`	Order for catalog calculation plugins.
`FLUX_ORDER`	Order for algorithms which require a shape and a centroid (`float`).
`SHAPE_ORDER`	Order for algorithms which require a centroid (`float`).
`registry`	Subclasses of `ForcedPlugin` must be registered here (`PluginRegistry`).

Methods Summary

`fail`(measRecord[, error])	Record a failure of the `measure` or `measureN` method.
`getExecutionOrder`()	Get the relative execution order of this plugin.
`getLogName`()
`getTransformClass`()	Get the measurement transformation appropriate to this plugin.
`measure`(measRecord, exposure, refRecord, refWcs)	Measure the properties of a source given an image and a reference.
`measureN`(measCat, exposure, refCat, refWcs)	Measure the properties of blended sources from image & reference.

Attributes Documentation

APCORR_ORDER = 3.0¶

Order for algorithms which require shape, centroid and flux (float).

Notes

These algorithms may assume that getCentroid and getShape will return good values, that flux has been measured, and that and that a Footprint and its Peaks are available.

CENTROID_ORDER = 0.0¶

Order for algorithms which require only Footprint and Peaks (float).

Notes

Algorithms with this execution order include centroids.

DEFAULT_CATALOGCALCULATION = 4.0¶

Order for catalog calculation plugins.

Notes

These plugins only operate on catalogs; they may not access pixel values.

FLUX_ORDER = 2.0¶

Order for algorithms which require a shape and a centroid (float).

Notes

These algorithms may assume that both getCentroid and getShape will return good values, and that a Footprint and its Peaks are available.

SHAPE_ORDER = 1.0¶

Order for algorithms which require a centroid (float).

Notes

These algorithms may refer assume that getCentroid will return a good centroid, and that a Footprint and its Peaks are available.

registry = <lsst.meas.base.pluginRegistry.PluginRegistry object>¶: Subclasses of ForcedPlugin must be registered here (PluginRegistry).

Methods Documentation

fail(measRecord, error=None)¶

Record a failure of the measure or measureN method.

Parameters:

measRecordlsst.afw.table.SourceRecord: Table record describing the source being measured.
errorMeasurementError, optional: Only provided if the measurement failed due to a MeasurementError being raised; otherwise, will be None.

Notes

When the plugin raises an exception, framework will call BasePlugin.fail to allow the plugin to set its failure flag field(s). When BasePlugin.measureN raises an exception, BasePlugin.fail will be called repeatedly with all the records that were being measured.

If the exception is an MeasurementError, it will be passed as the error argument; in all other cases the error argument will be None, and the failure will be logged by the measurement framework as a warning.

classmethod getExecutionOrder()¶

Get the relative execution order of this plugin.

Must be reimplemented as a class method by concrete derived classes.

getLogName()¶

static getTransformClass()¶

Get the measurement transformation appropriate to this plugin.

This returns a subclass of transforms.MeasurementTransform, which may be instantiated with details of the algorithm configuration and then called with information about calibration and WCS to convert from raw measurement quantities to calibrated units. Calibrated data is then provided in a separate output table.

Notes

By default, we copy everything from the input to the output without transformation.

measure(measRecord, exposure, refRecord, refWcs)¶

Measure the properties of a source given an image and a reference.

Parameters:

exposurelsst.afw.image.ExposureF: The pixel data to be measured, together with the associated PSF, WCS, etc. All other sources in the image should have been replaced by noise according to deblender outputs.
measRecordlsst.afw.table.SourceRecord: Record describing the object being measured. Previously-measured quantities will be retrieved from here, and it will be updated in-place with the outputs of this plugin.
refRecordlsst.afw.table.SimpleRecord: Additional parameters to define the fit, as measured elsewhere.
refWcslsst.afw.geom.SkyWcs or lsst.afw.geom.Angle: The coordinate system for the reference catalog values. An Angle may be passed, indicating that a local tangent WCS should be created for each object using the given angle as a pixel scale.

Notes

In the normal mode of operation, the source centroid will be set to the WCS-transformed position of the reference object, so plugins that only require a reference position should not have to access the reference object at all.

measureN(measCat, exposure, refCat, refWcs)¶

Measure the properties of blended sources from image & reference.

This operates on all members of a blend family at once.

Parameters:

exposurelsst.afw.image.ExposureF: The pixel data to be measured, together with the associated PSF, WCS, etc. Sources not in the blended hierarchy to be measured should have been replaced with noise using deblender outputs.
measCatlsst.afw.table.SourceCatalog: Catalog describing the objects (and only those objects) being measured. Previously-measured quantities will be retrieved from here, and it will be updated in-place with the outputs of this plugin.
refCatlsst.afw.table.SimpleCatalog: Additional parameters to define the fit, as measured elsewhere. Ordered such that zip(measCat, refcat) may be used.
refWcslsst.afw.geom.SkyWcs or lsst.afw.geom.Angle: The coordinate system for the reference catalog values. An Angle may be passed, indicating that a local tangent WCS should be created for each object using the given angle as a pixel scale.

Notes

In the normal mode of operation, the source centroids will be set to the WCS-transformed position of the reference object, so plugins that only require a reference position should not have to access the reference object at all.

Navigation

ForcedPeakCentroidPlugin¶