lsst::afw::geom::LinearTransform Class Reference

A 2D linear coordinate transformation. More...

#include <LinearTransform.h>

Public Types
enum	Parameters { XX =0, YX =1, XY =2, YY =3 }
typedef Eigen::Matrix< double, 4, 1 >	ParameterVector
typedef Eigen::Matrix< double, 2, 4 >	TransformDerivativeMatrix
typedef Eigen::Matrix< double, 4, 4 >	ProductDerivativeMatrix
typedef Eigen::Matrix< double, 2, 2, Eigen::DontAlign >	Matrix

Public Member Functions
	LinearTransform ()
	Construct an empty (identity) LinearTransform. More...
	LinearTransform (Matrix const &matrix)
	Construct an LinearTransform from an Eigen::Matrix. More...
LinearTransform	operator* (LinearTransform const &other) const
LinearTransform &	operator= (LinearTransform const &other)
ParameterVector const	getParameterVector () const
void	setParameterVector (ParameterVector const &vector)
Matrix const &	getMatrix () const
Matrix &	getMatrix ()
double &	operator[] (int i)
double const &	operator[] (int i) const
LinearTransform const	invert () const
double	computeDeterminant () const
bool	isIdentity () const
	Whether the transform is a no-op. More...
Point2D	operator() (Point2D const &p) const
	Transform a Point2D object. More...
Extent2D	operator() (Extent2D const &p) const
	Transform a Extent2D object. More...
TransformDerivativeMatrix	dTransform (Point2D const &input) const
TransformDerivativeMatrix	dTransform (Extent2D const &input) const
	Derivative of (*this)(input) with respect to the transform elements (for Extent);. More...

Static Public Member Functions
static LinearTransform	makeScaling (double s)
static LinearTransform	makeScaling (double s, double t)
static LinearTransform	makeRotation (Angle t)

Private Attributes
Matrix	_matrix

Detailed Description

A 2D linear coordinate transformation.

The transform is represented by a matrix \( \mathbf{M} \) such that

\[ \left[\begin{array}{ c } x_f \\ y_f \end{array}\right] = \mathbf{M} \left[\begin{array}{ c } x_i \\ y_i \end{array}\right] \]

where \((x_i,y_i)\) are the input coordinates and \((x_f,y_f)\) are the output coordinates.

If \( x_f(x_i,y_i) \) and \( y_f(x_i,y_i) \) are continuous differentiable functions, then

\[ \mathbf{M} = \left[\begin{array}{ c c } \displaystyle\frac{\partial x_f}{\partial x_i} & \displaystyle\frac{\partial x_f}{\partial y_i} \\ \displaystyle\frac{\partial y_f}{\partial x_i} & \displaystyle\frac{\partial y_f}{\partial y_i} \end{array}\right] \]

evaluated at \((x_i,y_i)\).

Definition at line 70 of file LinearTransform.h.

Member Typedef Documentation

typedef Eigen::Matrix<double,2,2,Eigen::DontAlign> lsst::afw::geom::LinearTransform::Matrix

Definition at line 78 of file LinearTransform.h.

typedef Eigen::Matrix<double,4,1> lsst::afw::geom::LinearTransform::ParameterVector

Definition at line 74 of file LinearTransform.h.

typedef Eigen::Matrix<double,4,4> lsst::afw::geom::LinearTransform::ProductDerivativeMatrix

Definition at line 76 of file LinearTransform.h.

typedef Eigen::Matrix<double,2,4> lsst::afw::geom::LinearTransform::TransformDerivativeMatrix

Definition at line 75 of file LinearTransform.h.

Member Enumeration Documentation

enum lsst::afw::geom::LinearTransform::Parameters

Enumerator
XX
YX
XY
YY

Definition at line 72 of file LinearTransform.h.

{XX=0,YX=1,XY=2,YY=3};

Constructor & Destructor Documentation

lsst::afw::geom::LinearTransform::LinearTransform ( )

inline

Construct an empty (identity) LinearTransform.

Definition at line 81 of file LinearTransform.h.

: _matrix(Matrix::Identity()) {}

lsst::afw::geom::LinearTransform::LinearTransform ( Matrix const &  matrix )

inlineexplicit

Construct an LinearTransform from an Eigen::Matrix.

Definition at line 84 of file LinearTransform.h.

: _matrix(matrix) {}

Member Function Documentation

double lsst::afw::geom::LinearTransform::computeDeterminant

(

)

const

TransformDerivativeMatrix lsst::afw::geom::LinearTransform::dTransform

(

Point2D const &

input

)

const

TransformDerivativeMatrix lsst::afw::geom::LinearTransform::dTransform ( Extent2D const &  input ) const

inline

Derivative of (*this)(input) with respect to the transform elements (for Extent);.

Definition at line 146 of file LinearTransform.h.

                                                                       {
        return dTransform(Point2D(input));
    }

Matrix const& lsst::afw::geom::LinearTransform::getMatrix ( ) const

inline

Definition at line 111 of file LinearTransform.h.

{ return _matrix; }

Matrix& lsst::afw::geom::LinearTransform::getMatrix ( )

inline

Definition at line 112 of file LinearTransform.h.

{ return _matrix; }

ParameterVector const lsst::afw::geom::LinearTransform::getParameterVector

(

)

const

LinearTransform const lsst::afw::geom::LinearTransform::invert

(

)

const

bool lsst::afw::geom::LinearTransform::isIdentity ( ) const

inline

Whether the transform is a no-op.

Definition at line 125 of file LinearTransform.h.

{ return getMatrix().isIdentity(); }

static LinearTransform lsst::afw::geom::LinearTransform::makeRotation ( Angle  t )

inlinestatic

Definition at line 99 of file LinearTransform.h.

                                                 {
        return LinearTransform(Matrix(Eigen::Rotation2D<double>(t.asRadians())));
    }

static LinearTransform lsst::afw::geom::LinearTransform::makeScaling ( double  s )

inlinestatic

Definition at line 91 of file LinearTransform.h.

                                                 { 
        return LinearTransform((Matrix() << s, 0.0, 0.0, s).finished());
    }

static LinearTransform lsst::afw::geom::LinearTransform::makeScaling ( double  s, double  t  )

inlinestatic

Definition at line 95 of file LinearTransform.h.

                                                           { 
        return LinearTransform((Matrix() << s, 0.0, 0.0, t).finished());
    }

Point2D lsst::afw::geom::LinearTransform::operator() ( Point2D const &  p ) const

inline

Transform a Point2D object.

This operation is equivalent to applying the LinearTransform to an lsst::afw::geom::Extent

Definition at line 133 of file LinearTransform.h.

{ return Point2D(getMatrix() * p.asEigen()); }

Extent2D lsst::afw::geom::LinearTransform::operator() ( Extent2D const &  p ) const

inline

Transform a Extent2D object.

This operation is equivalent to applying the LinearTransform to an lsst::afw::geom::Point

Definition at line 141 of file LinearTransform.h.

{ return Extent2D(getMatrix() * p.asEigen()); }

LinearTransform lsst::afw::geom::LinearTransform::operator* ( LinearTransform const &  other ) const

inline

Definition at line 86 of file LinearTransform.h.

                                                                   {
        return LinearTransform(getMatrix() * other.getMatrix());
    }

LinearTransform& lsst::afw::geom::LinearTransform::operator= ( LinearTransform const &  other )

inline

Definition at line 103 of file LinearTransform.h.

                                                               {
        _matrix = other._matrix;
        return *this;
    }

double& lsst::afw::geom::LinearTransform::operator[] ( int  i )

inline

Definition at line 114 of file LinearTransform.h.

{ return _matrix(i % 2, i / 2); }

double const& lsst::afw::geom::LinearTransform::operator[] ( int  i ) const

inline

Definition at line 115 of file LinearTransform.h.

                                           { 
        return const_cast<Matrix&>(_matrix)(i % 2, i / 2);
    }

void lsst::afw::geom::LinearTransform::setParameterVector

(

ParameterVector const &

vector

)

Member Data Documentation

Matrix lsst::afw::geom::LinearTransform::_matrix

private

Definition at line 151 of file LinearTransform.h.

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

• /home/lsstsw/stack/Linux64/afw/11.0-2-g04d2804/include/lsst/afw/geom/LinearTransform.h