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
enum	{ FAILURE =FlagHandler::FAILURE, NO_COUNTS, EDGE, N_FLAGS }
	Flag bits to be used with the 'flags' data member of the Result object. More...

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

virtual void	fail (afw::table::SourceRecord &measRecord, MeasurementError *error=NULL) const

Public Member Functions inherited from lsst::meas::base::SimpleAlgorithm
virtual void	measureForced (afw::table::SourceRecord &measRecord, afw::image::Exposure< float > const &exposure, afw::table::SourceRecord const &refRecord, afw::image::Wcs const &refWcs) const

virtual void	measureNForced (afw::table::SourceCatalog const &measCat, afw::image::Exposure< float > const &exposure, afw::table::SourceCatalog const &refRecord, afw::image::Wcs const &refWcs) const

Public Member Functions inherited from lsst::meas::base::SingleFrameAlgorithm
virtual void	measureN (afw::table::SourceCatalog const &measCat, afw::image::Exposure< float > const &exposure) const

Public Member Functions inherited from lsst::meas::base::BaseAlgorithm
virtual	~BaseAlgorithm ()

Private Attributes
Control	_ctrl

CentroidResultKey	_centroidKey

FlagHandler	_flagHandler

SafeCentroidExtractor	_centroidExtractor

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 62 of file NaiveCentroid.h.

Member Typedef Documentation

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

Definition at line 77 of file NaiveCentroid.h.

Member Enumeration Documentation

anonymous enum

Flag bits to be used with the 'flags' data member of the Result object.

Inspect getFlagDefinitions() for more detailed explanations of each flag.

Enumerator
FAILURE
NO_COUNTS
EDGE
N_FLAGS

Definition at line 70 of file NaiveCentroid.h.

          {
         FAILURE=FlagHandler::FAILURE,
         NO_COUNTS,
         EDGE,
         N_FLAGS
     };

Constructor & Destructor Documentation

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

Definition at line 43 of file NaiveCentroid.cc.

   : _ctrl(ctrl),
     _centroidKey(
         CentroidResultKey::addFields(schema, name, "centroid from Naive Centroid algorithm", NO_UNCERTAINTY)
     ),
     _centroidExtractor(schema, name, true)
 {
     _flagHandler = FlagHandler::addFields(schema, name,
                                           getFlagDefinitions().begin(), getFlagDefinitions().end());
 }

Member Function Documentation

void lsst::meas::base::NaiveCentroidAlgorithm::fail	(	afw::table::SourceRecord &	measRecord,
		MeasurementError *	error = `NULL`
	)		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 117 of file NaiveCentroid.cc.

                                                                                                    {
     _flagHandler.handleFailure(measRecord, error);
 }

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 57 of file NaiveCentroid.cc.

         {
     
     afw::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) {
 
         throw LSST_EXCEPT(
             MeasurementError,
             _flagHandler.getDefinition(EDGE).doc,
             EDGE
         );
     }
 
     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) {
         throw LSST_EXCEPT(
             MeasurementError,
             _flagHandler.getDefinition(NO_COUNTS).doc,
             NO_COUNTS
         );
     }
 
     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 = lsst::afw::image::indexToPosition(x + image.getX0()) + sum_x / sum;
     result.y = lsst::afw::image::indexToPosition(y + image.getY0()) + sum_y / sum;
     measRecord.set(_centroidKey, result);
     _flagHandler.setValue(measRecord, FAILURE, false);  // if we had a suspect flag, we'd set that instead
 }

Member Data Documentation

SafeCentroidExtractor lsst::meas::base::NaiveCentroidAlgorithm::_centroidExtractor

private

Definition at line 96 of file NaiveCentroid.h.

CentroidResultKey lsst::meas::base::NaiveCentroidAlgorithm::_centroidKey

private

Definition at line 94 of file NaiveCentroid.h.

Control lsst::meas::base::NaiveCentroidAlgorithm::_ctrl

private

Definition at line 93 of file NaiveCentroid.h.

FlagHandler lsst::meas::base::NaiveCentroidAlgorithm::_flagHandler

private

Definition at line 95 of file NaiveCentroid.h.

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

/home/lsstsw/stack/Linux64/meas_base/11.0+1/include/lsst/meas/base/NaiveCentroid.h
/home/lsstsw/stack/Linux64/meas_base/11.0+1/src/NaiveCentroid.cc

Public Types

Public Member Functions

Private Attributes

Detailed Description

Member Typedef Documentation

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation