lsst::meas::base::ShapeResult Struct Reference

A reusable struct for moments-based shape measurements. More...

#include <ShapeUtilities.h>

Inheritance diagram for lsst::meas::base::ShapeResult:

Public Member Functions
	ShapeResult ()
	Constructor; initializes everything to NaN.
	ShapeResult (ShapeElement xx_, ShapeElement yy_, ShapeElement xy_, ShapeCov const &matrix)
	Constructor; initializes everything from values.
	ShapeResult (ShapeElement xx_, ShapeElement yy_, ShapeElement xy_, ErrElement xxErr_, ErrElement yyErr_, ErrElement xyErr_)
	Constructor; initializes everything from values.
Shape const	getShape () const
	Return an afw::geom::ellipses object corresponding to xx, yy, xy.
afw::geom::ellipses::Quadrupole	getQuadrupole ()
void	setShape (Shape const &shape)
	Set struct elements from the given Quadrupole object.
ShapeCov const	getShapeErr () const
	Return the 3x3 symmetric covariance matrix, with rows and columns ordered (xx, yy, xy)
void	setShapeErr (ShapeCov const &matrix)
	Set the struct standard deviation elements from the given matrix, with rows and columns ordered (xx, yy, xy)
void	setShapeErr (ErrElement xxErr, ErrElement yyErr, ErrElement xyErr)
	Set the struct standard deviation elements from the given values.

Public Attributes
ShapeElement	xx
	image or model second moment for x^2
ShapeElement	yy
	image or model second moment for y^2
ShapeElement	xy
	image or model second moment for xy^2
ErrElement	xxErr
	standard deviation of xx
ErrElement	yyErr
	standard deviation of yy
ErrElement	xyErr
	standard deviation of xy
ErrElement	xx_yy_Cov
	xx,yy term in the uncertainty convariance matrix
ErrElement	xx_xy_Cov
	xx,xy term in the uncertainty convariance matrix
ErrElement	yy_xy_Cov
	yy,xy term in the uncertainty convariance matrix

Detailed Description

A reusable struct for moments-based shape measurements.

Shape measurements and their errors should always be in pixels coordinates. This struct should generally be preferred over a custom struct with other ellipse parametrizations unless the measurement takes place in another parametrization and a transformation to this one would result in a loss of information or obfuscate the results of the measurement (i.e. use this one unless you have a good reason not to).

Definition at line 43 of file ShapeUtilities.h.

Constructor & Destructor Documentation

ShapeResult() [1/3]

lsst::meas::base::ShapeResult::ShapeResult

(

)

Constructor; initializes everything to NaN.

Definition at line 30 of file ShapeUtilities.cc.

        : xx(std::numeric_limits<ShapeElement>::quiet_NaN()),
          yy(std::numeric_limits<ShapeElement>::quiet_NaN()),
          xy(std::numeric_limits<ShapeElement>::quiet_NaN()),
          xxErr(std::numeric_limits<ErrElement>::quiet_NaN()),
          yyErr(std::numeric_limits<ErrElement>::quiet_NaN()),
          xyErr(std::numeric_limits<ErrElement>::quiet_NaN()),
          xx_yy_Cov(std::numeric_limits<ErrElement>::quiet_NaN()),
          xx_xy_Cov(std::numeric_limits<ErrElement>::quiet_NaN()),
          yy_xy_Cov(std::numeric_limits<ErrElement>::quiet_NaN()) {}

ShapeResult() [2/3]

lsst::meas::base::ShapeResult::ShapeResult ( ShapeElement xx_, ShapeElement yy_, ShapeElement xy_, ShapeCov const & matrix )

inlineexplicit

Constructor; initializes everything from values.

Definition at line 58 of file ShapeUtilities.h.

            : xx(xx_),
              yy(yy_),
              xy(xy_),
              xxErr(std::sqrt(matrix(0, 0))),
              yyErr(std::sqrt(matrix(1, 1))),
              xyErr(std::sqrt(matrix(2, 2))),
              xx_yy_Cov(matrix(0, 1)),
              xx_xy_Cov(matrix(0, 2)),
              yy_xy_Cov(matrix(1, 2)) {}

ShapeResult() [3/3]

lsst::meas::base::ShapeResult::ShapeResult ( ShapeElement xx_, ShapeElement yy_, ShapeElement xy_, ErrElement xxErr_, ErrElement yyErr_, ErrElement xyErr_ )

inlineexplicit

Constructor; initializes everything from values.

Definition at line 70 of file ShapeUtilities.h.

            : xx(xx_),
              yy(yy_),
              xy(xy_),
              xxErr(xxErr_),
              yyErr(yyErr_),
              xyErr(xyErr_),
              xx_yy_Cov(0.0),
              xx_xy_Cov(0.0),
              yy_xy_Cov(0.0) {}

Member Function Documentation

getQuadrupole()

afw::geom::ellipses::Quadrupole lsst::meas::base::ShapeResult::getQuadrupole ( )

inline

Definition at line 91 of file ShapeUtilities.h.

{ return afw::geom::ellipses::Quadrupole(xx, yy, xy); }

getShape()

Shape const lsst::meas::base::ShapeResult::getShape

(

)

const

Return an afw::geom::ellipses object corresponding to xx, yy, xy.

This method can be used to return an average radius for the measured shape, e.g. getShape().getDeterminantRadius()

Definition at line 41 of file ShapeUtilities.cc.

{ return Shape(xx, yy, xy); }

getShapeErr()

ShapeCov const lsst::meas::base::ShapeResult::getShapeErr

(

)

const

Return the 3x3 symmetric covariance matrix, with rows and columns ordered (xx, yy, xy)

Definition at line 49 of file ShapeUtilities.cc.

                                              {
    ShapeCov m;
    m << xxErr * xxErr, xx_yy_Cov, xx_xy_Cov, xx_yy_Cov, yyErr * yyErr, yy_xy_Cov, xx_xy_Cov,
            yy_xy_Cov, xyErr * xyErr;
    return m;
}

setShape()

void lsst::meas::base::ShapeResult::setShape

(

Shape const &

shape

)

Set struct elements from the given Quadrupole object.

Definition at line 43 of file ShapeUtilities.cc.

                                             {
    xx = shape.getIxx();
    yy = shape.getIyy();
    xy = shape.getIxy();
}

setShapeErr() [1/2]

void lsst::meas::base::ShapeResult::setShapeErr	(	ErrElement	xxErr,
		ErrElement	yyErr,
		ErrElement	xyErr )

Set the struct standard deviation elements from the given values.

Definition at line 65 of file ShapeUtilities.cc.

                                                                                     {
    xxErr = _xxErr;
    yyErr = _yyErr;
    xyErr = _xyErr;
    xx_yy_Cov = 0.0;
    xx_xy_Cov = 0.0;
    yy_xy_Cov = 0.0;
}

setShapeErr() [2/2]

void lsst::meas::base::ShapeResult::setShapeErr

(

ShapeCov const &

matrix

)

Set the struct standard deviation elements from the given matrix, with rows and columns ordered (xx, yy, xy)

Definition at line 56 of file ShapeUtilities.cc.

                                                    {
    xxErr = std::sqrt(matrix(0, 0));
    yyErr = std::sqrt(matrix(1, 1));
    xyErr = std::sqrt(matrix(2, 2));
    xx_yy_Cov = matrix(0, 1);
    xx_xy_Cov = matrix(0, 2);
    yy_xy_Cov = matrix(1, 2);
}

Member Data Documentation

xx

ShapeElement lsst::meas::base::ShapeResult::xx

image or model second moment for x^2

Definition at line 44 of file ShapeUtilities.h.

xx_xy_Cov

ErrElement lsst::meas::base::ShapeResult::xx_xy_Cov

xx,xy term in the uncertainty convariance matrix

Definition at line 51 of file ShapeUtilities.h.

xx_yy_Cov

ErrElement lsst::meas::base::ShapeResult::xx_yy_Cov

xx,yy term in the uncertainty convariance matrix

Definition at line 50 of file ShapeUtilities.h.

xxErr

ErrElement lsst::meas::base::ShapeResult::xxErr

standard deviation of xx

Definition at line 47 of file ShapeUtilities.h.

xy

ShapeElement lsst::meas::base::ShapeResult::xy

image or model second moment for xy^2

Definition at line 46 of file ShapeUtilities.h.

xyErr

ErrElement lsst::meas::base::ShapeResult::xyErr

standard deviation of xy

Definition at line 49 of file ShapeUtilities.h.

yy

ShapeElement lsst::meas::base::ShapeResult::yy

image or model second moment for y^2

Definition at line 45 of file ShapeUtilities.h.

yy_xy_Cov

ErrElement lsst::meas::base::ShapeResult::yy_xy_Cov

yy,xy term in the uncertainty convariance matrix

Definition at line 52 of file ShapeUtilities.h.

yyErr

ErrElement lsst::meas::base::ShapeResult::yyErr

standard deviation of yy

Definition at line 48 of file ShapeUtilities.h.

---

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

• /j/snowflake/release/lsstsw/stack/lsst-scipipe-12.0.0/Linux/meas_base/g03191d30f7+9ce8016dbd/include/lsst/meas/base/ShapeUtilities.h
• /j/snowflake/release/lsstsw/stack/lsst-scipipe-12.0.0/Linux/meas_base/g03191d30f7+9ce8016dbd/src/ShapeUtilities.cc