lsst::jointcal::AstrometryTransform Class Reference

a virtual (interface) class for geometric transformations. More...

#include <AstrometryTransform.h>

Inheritance diagram for lsst::jointcal::AstrometryTransform:

Public Member Functions
virtual void	apply (const double xIn, const double yIn, double &xOut, double &yOut) const =0
void	apply (Point const &in, Point &out) const
	applies the tranfo to in and writes into out. Is indeed virtual. More...
Point	apply (Point const &in) const
	All these apply(..) shadow the virtual one in derived classes, unless one writes "using AstrometryTransform::apply". More...
Frame	apply (Frame const &inputframe, bool inscribed) const
	Transform a bounding box, taking either the inscribed or circumscribed box. More...
virtual void	print (std::ostream &out) const =0
	prints the transform coefficients to stream. More...
std::string	__str__ ()
virtual double	fit (StarMatchList const &starMatchList)=0
	fits a transform to a std::list of Point pairs (p1,p2, the Point fields in StarMatch). More...
void	transformStar (FatPoint &in) const
virtual double	getJacobian (Point const &point) const
	returns the local jacobian. More...
virtual std::unique_ptr< AstrometryTransform >	clone () const =0
	returns a copy (allocated by new) of the transformation. More...
virtual std::unique_ptr< AstrometryTransform >	composeAndReduce (AstrometryTransform const &right) const
	Return a reduced composition of newTransform = this(right()), or nullptr if it cannot be reduced. More...
virtual double	getJacobian (const double x, const double y) const
	returns the local jacobian. More...
virtual void	computeDerivative (Point const &where, AstrometryTransformLinear &derivative, const double step=0.01) const
	Computes the local Derivative of a transform, w.r.t. More...
virtual AstrometryTransformLinear	linearApproximation (Point const &where, const double step=0.01) const
	linear (local) approximation. More...
virtual void	transformPosAndErrors (const FatPoint &in, FatPoint &out) const
virtual void	transformErrors (Point const &where, const double *vIn, double *vOut) const
	transform errors (represented as double[3] in order V(xx),V(yy),Cov(xy)) More...
virtual std::unique_ptr< AstrometryTransform >	inverseTransform (const double precision, const Frame &region) const
	returns an inverse transform. Numerical if not overloaded. More...
void	getParams (double *params) const
	params should be at least Npar() long More...
void	offsetParams (Eigen::VectorXd const &delta)
virtual double	paramRef (Eigen::Index const i) const
virtual double &	paramRef (Eigen::Index const i)
virtual void	paramDerivatives (Point const &where, double *dx, double *dy) const
	Derivative w.r.t parameters. More...
virtual std::unique_ptr< AstrometryTransform >	roughInverse (const Frame &region) const
	Rough inverse. More...
virtual std::size_t	getNpar () const
	returns the number of parameters (to compute chi2's) More...
virtual std::shared_ptr< ast::Mapping >	toAstMap (jointcal::Frame const &domain) const
	Create an equivalent AST mapping for this transformation, including an analytic inverse if possible. More...
void	write (const std::string &fileName) const
virtual void	write (std::ostream &stream) const
virtual	~AstrometryTransform ()

Detailed Description

a virtual (interface) class for geometric transformations.

We implement here One AstrometryTransform interface class, and actual derived classes. Composition in the usual (mathematical) sense is provided using compose(), and some classes (e.g. AstrometryTransformLinear) handle a * operator. Generic inversion by iteration exists, but it is at least 10 times slower than the corresponding "direct transformation". If a transform has an analytical inverse, then providing inverseTransform is obviously a very good idea. Before resorting to inverseTransform, consider using StarMatchList::inverseTransform(). AstrometryTransformLinear::inverted() and TanPixelToRaDec::inverted() exist. The classes also provide derivation and linear approximation.

Definition at line 65 of file AstrometryTransform.h.

Constructor & Destructor Documentation

~AstrometryTransform()

virtual lsst::jointcal::AstrometryTransform::~AstrometryTransform ( )

inlinevirtual

Definition at line 197 of file AstrometryTransform.h.

{};

Member Function Documentation

__str__()

std::string lsst::jointcal::AstrometryTransform::__str__ ( )

inline

Definition at line 94 of file AstrometryTransform.h.

                        {
        std::stringstream s;
        print(s);
        return s.str();
    }

apply() [1/4]

virtual void lsst::jointcal::AstrometryTransform::apply ( const double  xIn, const double  yIn, double &  xOut, double &  yOut  ) const

pure virtual

Implemented in lsst::jointcal::AstrometryTransformSkyWcs, lsst::jointcal::AstrometryTransformPolynomial, lsst::jointcal::AstrometryTransformIdentity, lsst::jointcal::AstrometryTransformComposition, lsst::jointcal::AstrometryTransformInverse, lsst::jointcal::UserTransform, lsst::jointcal::TanRaDecToPixel, and lsst::jointcal::BaseTanWcs.

apply() [2/4]

Frame lsst::jointcal::AstrometryTransform::apply	(	Frame const &	inputframe,
		bool	inscribed
	)		const

Transform a bounding box, taking either the inscribed or circumscribed box.

Parameters

[in]	inputframe	The frame to be transformed.
[in]	inscribed	Return the inscribed (true) or circumscribed (false) box.

Returns

The transformed frame.

Definition at line 76 of file AstrometryTransform.cc.

                                                                              {
    // 2 opposite corners
    double xtmin1, xtmax1, ytmin1, ytmax1;
    apply(inputframe.xMin, inputframe.yMin, xtmin1, ytmin1);
    apply(inputframe.xMax, inputframe.yMax, xtmax1, ytmax1);
    Frame fr1(std::min(xtmin1, xtmax1), std::min(ytmin1, ytmax1), std::max(xtmin1, xtmax1),
              std::max(ytmin1, ytmax1));
    // 2 other corners
    double xtmin2, xtmax2, ytmin2, ytmax2;
    apply(inputframe.xMin, inputframe.yMax, xtmin2, ytmax2);
    apply(inputframe.xMax, inputframe.yMin, xtmax2, ytmin2);
    Frame fr2(std::min(xtmin2, xtmax2), std::min(ytmin2, ytmax2), std::max(xtmin2, xtmax2),
              std::max(ytmin2, ytmax2));
 
    if (inscribed) return fr1 * fr2;
    return fr1 + fr2;
}

apply() [3/4]

Point lsst::jointcal::AstrometryTransform::apply ( Point const &  in ) const

inline

All these apply(..) shadow the virtual one in derived classes, unless one writes "using AstrometryTransform::apply".

Definition at line 75 of file AstrometryTransform.h.

                                       {
        double xout, yout;
        apply(in.x, in.y, xout, yout);
        return Point(xout, yout);
    }

apply() [4/4]

void lsst::jointcal::AstrometryTransform::apply ( Point const &  in, Point &  out  ) const

inline

applies the tranfo to in and writes into out. Is indeed virtual.

Definition at line 71 of file AstrometryTransform.h.

{ apply(in.x, in.y, out.x, out.y); }

clone()

virtual std::unique_ptr<AstrometryTransform> lsst::jointcal::AstrometryTransform::clone ( ) const

pure virtual

returns a copy (allocated by new) of the transformation.

Implemented in lsst::jointcal::AstrometryTransformSkyWcs, lsst::jointcal::AstrometryTransformLinear, lsst::jointcal::AstrometryTransformPolynomial, lsst::jointcal::AstrometryTransformIdentity, lsst::jointcal::AstrometryTransformComposition, lsst::jointcal::AstrometryTransformInverse, lsst::jointcal::UserTransform, lsst::jointcal::TanRaDecToPixel, lsst::jointcal::TanSipPixelToRaDec, and lsst::jointcal::TanPixelToRaDec.

composeAndReduce()

std::unique_ptr< AstrometryTransform > lsst::jointcal::AstrometryTransform::composeAndReduce ( AstrometryTransform const &  right ) const

virtual

Return a reduced composition of newTransform = this(right()), or nullptr if it cannot be reduced.

"Reduced" in this context means that they are capable of being merged into a single transform, for example, for two polynomials:

\[ f(x) = 1 + x^2, g(x) = -1 + 3x \]

we would have h = f.composeAndReduce(g) == 2 - 6x + 9x^2.

To be overloaded by derived classes if they can properly reduce the composition.

Parameters

right

The transform to apply first.

Returns

The new reduced and composed AstrometryTransform, or nullptr if no such reduction is possible.

Reimplemented in lsst::jointcal::AstrometryTransformIdentity.

Definition at line 94 of file AstrometryTransform.cc.

                                           {  // by default no way to compose
    return std::unique_ptr<AstrometryTransform>(nullptr);
}

computeDerivative()

void lsst::jointcal::AstrometryTransform::computeDerivative ( Point const &  where, AstrometryTransformLinear &  derivative, const double  step = 0.01  ) const

virtual

Computes the local Derivative of a transform, w.r.t.

the Derivative is represented by a AstrometryTransformLinear, in which (hopefully), the offset terms are zero.

position.

Step is used for numerical derivation.

Derivative should transform a vector of offsets into a vector of offsets.

Reimplemented in lsst::jointcal::AstrometryTransformLinear, lsst::jointcal::AstrometryTransformPolynomial, and lsst::jointcal::AstrometryTransformIdentity.

Definition at line 118 of file AstrometryTransform.cc.

                                                                     {
    double x = where.x;
    double y = where.y;
    double xp0, yp0;
    apply(x, y, xp0, yp0);
 
    double xp, yp;
    apply(x + step, y, xp, yp);
    derivative.a11() = (xp - xp0) / step;
    derivative.a21() = (yp - yp0) / step;
    apply(x, y + step, xp, yp);
    derivative.a12() = (xp - xp0) / step;
    derivative.a22() = (yp - yp0) / step;
    derivative.dx() = 0;
    derivative.dy() = 0;
}

fit()

virtual double lsst::jointcal::AstrometryTransform::fit ( StarMatchList const &  starMatchList )

pure virtual

fits a transform to a std::list of Point pairs (p1,p2, the Point fields in StarMatch).

After the fit this(p1) yields approximately p2. The returned value is the sum of squared residuals. If you want to fit a partial transform (e.g. such that this(T1(p1)) = T2(p2), use StarMatchList::applyTransform beforehand.

Implemented in lsst::jointcal::AstrometryTransformPolynomial, lsst::jointcal::AstrometryTransformIdentity, lsst::jointcal::AstrometryTransformComposition, lsst::jointcal::AstrometryTransformInverse, lsst::jointcal::UserTransform, lsst::jointcal::TanRaDecToPixel, lsst::jointcal::TanSipPixelToRaDec, lsst::jointcal::TanPixelToRaDec, lsst::jointcal::AstrometryTransformLinearRot, lsst::jointcal::AstrometryTransformLinearShift, and lsst::jointcal::AstrometryTransformSkyWcs.

getJacobian() [1/2]

double lsst::jointcal::AstrometryTransform::getJacobian ( const double  x, const double  y  ) const

virtual

returns the local jacobian.

Definition at line 99 of file AstrometryTransform.cc.

                                                                            {
    double x2, y2;
    double eps = x * 0.01;
    if (eps == 0) eps = 0.01;
    apply(x, y, x2, y2);
    double dxdx, dydx;
    apply(x + eps, y, dxdx, dydx);
    dxdx -= x2;
    dydx -= y2;
    double dxdy, dydy;
    apply(x, y + eps, dxdy, dydy);
    dxdy -= x2;
    dydy -= y2;
    return ((dxdx * dydy - dxdy * dydx) / (eps * eps));
}

getJacobian() [2/2]

virtual double lsst::jointcal::AstrometryTransform::getJacobian ( Point const &  point ) const

inlinevirtual

returns the local jacobian.

Definition at line 110 of file AstrometryTransform.h.

{ return getJacobian(point.x, point.y); }

getNpar()

virtual std::size_t lsst::jointcal::AstrometryTransform::getNpar ( ) const

inlinevirtual

returns the number of parameters (to compute chi2's)

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial, lsst::jointcal::AstrometryTransformIdentity, lsst::jointcal::AstrometryTransformLinearScale, lsst::jointcal::AstrometryTransformLinearRot, and lsst::jointcal::AstrometryTransformLinearShift.

Definition at line 180 of file AstrometryTransform.h.

{ return 0; }

getParams()

void lsst::jointcal::AstrometryTransform::getParams

(

double *

params

)

const

params should be at least Npar() long

Definition at line 216 of file AstrometryTransform.cc.

                                                        {
    std::size_t npar = getNpar();
    for (std::size_t i = 0; i < npar; ++i) params[i] = paramRef(i);
}

inverseTransform()

std::unique_ptr< AstrometryTransform > lsst::jointcal::AstrometryTransform::inverseTransform ( const double  precision, const Frame &  region  ) const

virtual

returns an inverse transform. Numerical if not overloaded.

precision and region refer to the "input" side of this, and hence to the output side of the returned AstrometryTransform.

Reimplemented in lsst::jointcal::AstrometryTransformInverse, lsst::jointcal::AstrometryTransformLinear, lsst::jointcal::TanRaDecToPixel, lsst::jointcal::TanSipPixelToRaDec, and lsst::jointcal::TanPixelToRaDec.

Definition at line 303 of file AstrometryTransform.cc.

                                                                                                      {
    return std::unique_ptr<AstrometryTransform>(new AstrometryTransformInverse(this, precision, region));
}

linearApproximation()

AstrometryTransformLinear lsst::jointcal::AstrometryTransform::linearApproximation ( Point const &  where, const double  step = 0.01  ) const

virtual

linear (local) approximation.

Reimplemented in lsst::jointcal::AstrometryTransformLinear, and lsst::jointcal::AstrometryTransformIdentity.

Definition at line 136 of file AstrometryTransform.cc.

                                                                                            {
    Point outwhere = apply(where);
    AstrometryTransformLinear der;
    computeDerivative(where, der, step);
    return AstrometryTransformLinearShift(outwhere.x, outwhere.y) * der *
           AstrometryTransformLinearShift(-where.x, -where.y);
}

offsetParams()

void lsst::jointcal::AstrometryTransform::offsetParams

(

Eigen::VectorXd const &

delta

)

Definition at line 221 of file AstrometryTransform.cc.

                                                                 {
    std::size_t npar = getNpar();
    for (std::size_t i = 0; i < npar; ++i) paramRef(i) += delta[i];
}

paramDerivatives()

void lsst::jointcal::AstrometryTransform::paramDerivatives ( Point const &  where, double *  dx, double *  dy  ) const

virtual

Derivative w.r.t parameters.

Derivatives should be al least 2*NPar long. first Npar, for x, last Npar for y.

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial.

Definition at line 236 of file AstrometryTransform.cc.

                                                                                  {
    throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
                      "AstrometryTransform::paramDerivatives() should never be called ");
}

paramRef() [1/2]

double & lsst::jointcal::AstrometryTransform::paramRef ( Eigen::Index const  i )

virtual

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial.

Definition at line 231 of file AstrometryTransform.cc.

                                                      {
    throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
                      "AstrometryTransform::paramRef should never be called ");
}

paramRef() [2/2]

double lsst::jointcal::AstrometryTransform::paramRef ( Eigen::Index const  i ) const

virtual

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial.

Definition at line 226 of file AstrometryTransform.cc.

                                                           {
    throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
                      std::string("AstrometryTransform::paramRef should never be called "));
}

print()

virtual void lsst::jointcal::AstrometryTransform::print ( std::ostream &  out ) const

pure virtual

prints the transform coefficients to stream.

Implemented in lsst::jointcal::AstrometryTransformSkyWcs, lsst::jointcal::AstrometryTransformLinear, lsst::jointcal::AstrometryTransformPolynomial, lsst::jointcal::AstrometryTransformIdentity, lsst::jointcal::UserTransform, lsst::jointcal::TanRaDecToPixel, lsst::jointcal::TanSipPixelToRaDec, lsst::jointcal::TanPixelToRaDec, lsst::jointcal::AstrometryTransformComposition, and lsst::jointcal::AstrometryTransformInverse.

roughInverse()

std::unique_ptr< AstrometryTransform > lsst::jointcal::AstrometryTransform::roughInverse ( const Frame &  region ) const

virtual

Rough inverse.

Stored by the numerical inverter to guess starting point for the trials. Just here to enable overloading.

Reimplemented in lsst::jointcal::TanRaDecToPixel, lsst::jointcal::TanPixelToRaDec, and lsst::jointcal::AstrometryTransformInverse.

Definition at line 195 of file AstrometryTransform.cc.

                                                                                              {
    // "in" and "out" refer to the inverse direction.
    Point centerOut = region.getCenter();
    Point centerIn = apply(centerOut);
    AstrometryTransformLinear der;
    computeDerivative(centerOut, der, std::sqrt(region.getArea()) / 5.);
    der = der.inverted();
    der = AstrometryTransformLinearShift(centerOut.x, centerOut.y) * der *
          AstrometryTransformLinearShift(-centerIn.x, -centerIn.y);
    return std::unique_ptr<AstrometryTransform>(new AstrometryTransformLinear(der));
}

toAstMap()

virtual std::shared_ptr<ast::Mapping> lsst::jointcal::AstrometryTransform::toAstMap ( jointcal::Frame const &  domain ) const

inlinevirtual

Create an equivalent AST mapping for this transformation, including an analytic inverse if possible.

Parameters

domain

The domain of the transform, to help find an inverse.

Returns

An AST Mapping that represents this transformation.

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial, and lsst::jointcal::AstrometryTransformIdentity.

Definition at line 189 of file AstrometryTransform.h.

                                                                                  {
        throw std::logic_error("toAstMap is not implemented for this class.");
    }

transformErrors()

void lsst::jointcal::AstrometryTransform::transformErrors ( Point const &  where, const double *  vIn, double *  vOut  ) const

virtual

transform errors (represented as double[3] in order V(xx),V(yy),Cov(xy))

Definition at line 162 of file AstrometryTransform.cc.

                                                                                                   {
    AstrometryTransformLinear der;
    computeDerivative(where, der, 0.01);
    double a11 = der.A11();
    double a22 = der.A22();
    double a21 = der.A21();
    double a12 = der.A12();
 
    /*      (a11 a12)          (vxx  vxy)
       M =  (       )  and V = (        )
            (a21 a22)          (xvy  vyy)
 
       Vxx = Vin[0], vyy = Vin[1], Vxy = Vin[2];
       we want to compute M*V*tp(M)
       A lin alg light package would be perfect...
    */
    int xx = 0;
    int yy = 1;
    int xy = 2;
    // M*V :
 
    double b11 = a11 * vIn[xx] + a12 * vIn[xy];
    double b22 = a21 * vIn[xy] + a22 * vIn[yy];
    double b12 = a11 * vIn[xy] + a12 * vIn[yy];
    double b21 = a21 * vIn[xx] + a22 * vIn[xy];
 
    // (M*V) * tp(M)
 
    vOut[xx] = b11 * a11 + b12 * a12;
    vOut[xy] = b11 * a21 + b12 * a22;
    vOut[yy] = b21 * a21 + b22 * a22;
}

transformPosAndErrors()

void lsst::jointcal::AstrometryTransform::transformPosAndErrors ( const FatPoint &  in, FatPoint &  out  ) const

virtual

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial, and lsst::jointcal::TanRaDecToPixel.

Definition at line 145 of file AstrometryTransform.cc.

                                                                                       {
    FatPoint res;  // in case in and out are the same address...
    res = apply(in);
    AstrometryTransformLinear der;
    // could save a call here, since Derivative needs the transform of where that we already have
    // 0.01 may not be a very good idea in all cases. May be we should provide a way of altering that.
    computeDerivative(in, der, 0.01);
    double a11 = der.A11();
    double a22 = der.A22();
    double a21 = der.A21();
    double a12 = der.A12();
    res.vx = a11 * (a11 * in.vx + 2 * a12 * in.vxy) + a12 * a12 * in.vy;
    res.vy = a21 * a21 * in.vx + a22 * a22 * in.vy + 2. * a21 * a22 * in.vxy;
    res.vxy = a21 * a11 * in.vx + a22 * a12 * in.vy + (a21 * a12 + a11 * a22) * in.vxy;
    out = res;
}

transformStar()

void lsst::jointcal::AstrometryTransform::transformStar ( FatPoint &  in ) const

inline

Definition at line 107 of file AstrometryTransform.h.

{ transformPosAndErrors(in, in); }

write() [1/2]

void lsst::jointcal::AstrometryTransform::write

(

const std::string &

fileName

)

const

Definition at line 246 of file AstrometryTransform.cc.

                                                               {
    ofstream s(fileName.c_str());
    write(s);
    bool ok = !s.fail();
    s.close();
    if (!ok)
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
                          "AstrometryTransform::write, something went wrong for file " + fileName);
}

write() [2/2]

void lsst::jointcal::AstrometryTransform::write ( std::ostream &  stream ) const

virtual

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial, and lsst::jointcal::AstrometryTransformIdentity.

Definition at line 256 of file AstrometryTransform.cc.

                                                     {
    throw LSST_EXCEPT(
            pex::exceptions::InvalidParameterError,
            "AstrometryTransform::write(ostream), should never be called. MEans that it is missing in some "
            "derived class ");
}

---

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

• /j/snowflake/release/lsstsw/stack/lsst-scipipe-0.7.0/Linux64/jointcal/22.0.1-25-g5bf6245+3ad8ecd50b/include/lsst/jointcal/AstrometryTransform.h
• /j/snowflake/release/lsstsw/stack/lsst-scipipe-0.7.0/Linux64/jointcal/22.0.1-25-g5bf6245+3ad8ecd50b/src/AstrometryTransform.cc