lsst::meas::base::NaiveCentroidAlgorithm Class Reference

A class that calculates a centroid as a simple unweighted first moment of the 3x3 region around a pixel. More...

#include <NaiveCentroid.h>

Inheritance diagram for lsst::meas::base::NaiveCentroidAlgorithm:

Public Types
typedef NaiveCentroidControl	Control

Public Member Functions
	NaiveCentroidAlgorithm (Control const &ctrl, std::string const &name, afw::table::Schema &schema)
virtual void	measure (afw::table::SourceRecord &measRecord, afw::image::Exposure< float > const &exposure) const
	Called to measure a single child source in an image.
virtual void	fail (afw::table::SourceRecord &measRecord, MeasurementError *error=nullptr) const
	Handle an exception thrown by the current algorithm by setting flags in the given record.
void	measureForced (afw::table::SourceRecord &measRecord, afw::image::Exposure< float > const &exposure, afw::table::SourceRecord const &refRecord, afw::geom::SkyWcs const &refWcs) const override
	Called to measure a single child source in an image.
void	measureNForced (afw::table::SourceCatalog const &measCat, afw::image::Exposure< float > const &exposure, afw::table::SourceCatalog const &refRecord, afw::geom::SkyWcs const &refWcs) const override
	Called to simultaneously measure all children in a deblend family, in a single image.
virtual void	measureN (afw::table::SourceCatalog const &measCat, afw::image::Exposure< float > const &exposure) const
	Called to simultaneously measure all children in a deblend family, in a single image.
std::string	getLogName () const

Static Public Member Functions
static FlagDefinitionList const &	getFlagDefinitions ()

Static Public Attributes
static FlagDefinition const	FAILURE = flagDefinitions.addFailureFlag()
static FlagDefinition const	NO_COUNTS
static FlagDefinition const	EDGE

Protected Attributes
std::string	_logName

Detailed Description

A class that calculates a centroid as a simple unweighted first moment of the 3x3 region around a pixel.

A fixed background (set via config) may optionally be subtracted. This algorithm does not currently report an error, but it probably should.

Definition at line 71 of file NaiveCentroid.h.

Member Typedef Documentation

Control

typedef NaiveCentroidControl lsst::meas::base::NaiveCentroidAlgorithm::Control

Definition at line 81 of file NaiveCentroid.h.

Constructor & Destructor Documentation

NaiveCentroidAlgorithm()

lsst::meas::base::NaiveCentroidAlgorithm::NaiveCentroidAlgorithm	(	Control const &	ctrl,
		std::string const &	name,
		afw::table::Schema &	schema )

Definition at line 42 of file NaiveCentroid.cc.

        : _ctrl(ctrl),
          _centroidKey(CentroidResultKey::addFields(schema, name, "centroid from Naive Centroid algorithm",
                                                    NO_UNCERTAINTY)),
          _flagHandler(FlagHandler::addFields(schema, name, getFlagDefinitions())),
          _centroidExtractor(schema, name, true),
          _centroidChecker(schema, name, ctrl.doFootprintCheck, ctrl.maxDistToPeak) {}

Member Function Documentation

fail()

void lsst::meas::base::NaiveCentroidAlgorithm::fail ( afw::table::SourceRecord & measRecord, MeasurementError * error = nullptr ) const

virtual

Handle an exception thrown by the current algorithm by setting flags in the given record.

fail() is called by the measurement framework when an exception is allowed to propagate out of one the algorithm's measure() methods. It should generally set both a general failure flag for the algorithm as well as a specific flag indicating the error condition, if possible. To aid in this, if the exception was an instance of MeasurementError, it will be passed in, carrying information about what flag to set.

An algorithm can also to chose to set flags within its own measure() methods, and then just return, rather than throw an exception. However, fail() should be implemented even when all known failure modes do not throw exceptions, to ensure that unexpected exceptions thrown in lower-level code are properly handled.

Implements lsst::meas::base::BaseAlgorithm.

Definition at line 95 of file NaiveCentroid.cc.

                                                                                                 {
    _flagHandler.handleFailure(measRecord, error);
}

getFlagDefinitions()

FlagDefinitionList const & lsst::meas::base::NaiveCentroidAlgorithm::getFlagDefinitions ( )

static

Definition at line 40 of file NaiveCentroid.cc.

{ return flagDefinitions; }

getLogName()

std::string lsst::meas::base::BaseAlgorithm::getLogName ( ) const

inlineinherited

Definition at line 66 of file Algorithm.h.

{ return _logName; }

measure()

void lsst::meas::base::NaiveCentroidAlgorithm::measure ( afw::table::SourceRecord & measRecord, afw::image::Exposure< float > const & exposure ) const

virtual

Called to measure a single child source in an image.

Before this method is called, all neighbors will be replaced with noise, using the outputs of the deblender. Outputs should be saved in the given SourceRecord, which can also be used to obtain centroid (see SafeCentroidExtractor) and shape (see SafeShapeExtractor) information.

Implements lsst::meas::base::SingleFrameAlgorithm.

Definition at line 51 of file NaiveCentroid.cc.

                                                                                    {
    geom::Point2D center = _centroidExtractor(measRecord, _flagHandler);
    CentroidResult result;
    result.x = center.getX();
    result.y = center.getY();
    measRecord.set(_centroidKey, result);  // better than NaN
 
    typedef afw::image::Image<float> ImageT;
    ImageT const& image = *exposure.getMaskedImage().getImage();
 
    int x = center.getX();  // FIXME: this is different from GaussianCentroid and SdssCentroid here,
    int y = center.getY();  //        and probably shouldn't be.
 
    x -= image.getX0();  // work in image Pixel coordinates
    y -= image.getY0();
 
    if (x < 1 || x >= image.getWidth() - 1 || y < 1 || y >= image.getHeight() - 1) {
        _flagHandler.setValue(measRecord, EDGE.number, true);
        _flagHandler.setValue(measRecord, NaiveCentroidAlgorithm::FAILURE.number, true);
        return;
    }
 
    ImageT::xy_locator im = image.xy_at(x, y);
 
    double const sum = (im(-1, 1) + im(0, 1) + im(1, 1) + im(-1, 0) + im(0, 0) + im(1, 0) + im(-1, -1) +
                        im(0, -1) + im(1, -1)) -
                       9 * _ctrl.background;
 
    if (sum == 0.0) {
        _flagHandler.setValue(measRecord, NO_COUNTS.number, true);
        _flagHandler.setValue(measRecord, NaiveCentroidAlgorithm::FAILURE.number, true);
        return;
    }
 
    double const sum_x = -im(-1, 1) + im(1, 1) + -im(-1, 0) + im(1, 0) + -im(-1, -1) + im(1, -1);
    double const sum_y = (im(-1, 1) + im(0, 1) + im(1, 1)) - (im(-1, -1) + im(0, -1) + im(1, -1));
 
    result.x = afw::image::indexToPosition(x + image.getX0()) + sum_x / sum;
    result.y = afw::image::indexToPosition(y + image.getY0()) + sum_y / sum;
    measRecord.set(_centroidKey, result);
    _centroidChecker(measRecord);
}

measureForced()

void lsst::meas::base::SimpleAlgorithm::measureForced ( afw::table::SourceRecord & measRecord, afw::image::Exposure< float > const & exposure, afw::table::SourceRecord const & refRecord, afw::geom::SkyWcs const & refWcs ) const

inlineoverridevirtualinherited

Called to measure a single child source in an image.

Before this method is called, all neighbors will be replaced with noise, using the outputs of the deblender. Outputs should be saved in the given SourceRecord, which can also be used to obtain centroid (see SafeCentroidExtractor) and shape (see SafeShapeExtractor) information.

Implements lsst::meas::base::ForcedAlgorithm.

Reimplemented in lsst::meas::extensions::photometryKron::KronFluxAlgorithm.

Definition at line 172 of file Algorithm.h.

                                                                           {
        measure(measRecord, exposure);
    }

measureN()

void lsst::meas::base::SingleFrameAlgorithm::measureN ( afw::table::SourceCatalog const & measCat, afw::image::Exposure< float > const & exposure ) const

virtualinherited

Called to simultaneously measure all children in a deblend family, in a single image.

Outputs should be saved in the given SourceCatalog, which can also be used to obtain centroid (see SafeCentroidExtractor) and shape (see SafeShapeExtractor) information.

The default implementation simply throws an exception, indicating that simultaneous measurement is not supported.

Definition at line 31 of file Algorithm.cc.

                                                                                   {
    throw LSST_EXCEPT(pex::exceptions::LogicError, "measureN not implemented for this algorithm");
}

measureNForced()

void lsst::meas::base::SimpleAlgorithm::measureNForced ( afw::table::SourceCatalog const & measCat, afw::image::Exposure< float > const & exposure, afw::table::SourceCatalog const & refRecord, afw::geom::SkyWcs const & refWcs ) const

inlineoverridevirtualinherited

Called to simultaneously measure all children in a deblend family, in a single image.

Outputs should be saved in the given SourceCatalog, which can also be used to obtain centroid (see SafeCentroidExtractor) and shape (see SafeShapeExtractor) information.

The default implementation simply throws an exception, indicating that simultaneous measurement is not supported.

Reimplemented from lsst::meas::base::ForcedAlgorithm.

Definition at line 179 of file Algorithm.h.

                                                                            {
        measureN(measCat, exposure);
    }

Member Data Documentation

_logName

std::string lsst::meas::base::BaseAlgorithm::_logName

protectedinherited

Definition at line 69 of file Algorithm.h.

EDGE

FlagDefinition const lsst::meas::base::NaiveCentroidAlgorithm::EDGE

static

Initial value:

=
        flagDefinitions.add("flag_edge", "Object too close to edge")

Definition at line 79 of file NaiveCentroid.h.

FAILURE

FlagDefinition const lsst::meas::base::NaiveCentroidAlgorithm::FAILURE = flagDefinitions.addFailureFlag()

static

Definition at line 77 of file NaiveCentroid.h.

NO_COUNTS

FlagDefinition const lsst::meas::base::NaiveCentroidAlgorithm::NO_COUNTS

static

Initial value:

=
        flagDefinitions.add("flag_noCounts", "Object to be centroided has no counts")

Definition at line 78 of file NaiveCentroid.h.

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

• /j/snowflake/release/lsstsw/stack/lsst-scipipe-9.0.0/Linux64/meas_base/g217e2c1bcf+937a289c59/include/lsst/meas/base/NaiveCentroid.h
• /j/snowflake/release/lsstsw/stack/lsst-scipipe-9.0.0/Linux64/meas_base/g217e2c1bcf+937a289c59/src/NaiveCentroid.cc