lsst::jointcal::TanRaDecToPixel Class Reference

This one is the Tangent Plane (called gnomonic) projection (from celestial sphere to tangent plane) More...

#include <AstrometryTransform.h>

Inheritance diagram for lsst::jointcal::TanRaDecToPixel:

Public Member Functions
	TanRaDecToPixel (AstrometryTransformLinear const &tan2Pix, Point const &tangentPoint)
	assume degrees everywhere. More...
	TanRaDecToPixel ()
AstrometryTransformLinear	getLinPart () const
	The Linear part (corresponding to CD's and CRPIX's) More...
void	setTangentPoint (Point const &tangentPoint)
	Resets the projection (or tangent) point. More...
Point	getTangentPoint () const
	tangent point coordinates (degrees) More...
void	apply (const double xIn, const double yIn, double &xOut, double &yOut) const
void	transformPosAndErrors (const FatPoint &in, FatPoint &out) const
	transform with analytical derivatives More...
TanPixelToRaDec	inverted () const
	exact typed inverse: More...
std::unique_ptr< AstrometryTransform >	roughInverse (const Frame &region) const
	Overload the "generic routine" (available for all AstrometryTransform types. More...
std::unique_ptr< AstrometryTransform >	inverseTransform (const double precision, const Frame &region) const
	Inverse transform: returns a TanPixelToRaDec. More...
void	dump (std::ostream &stream) const
	dumps the transform coefficients to stream. More...
std::unique_ptr< AstrometryTransform >	clone () const
	returns a copy (allocated by new) of the transformation. More...
double	fit (StarMatchList const &starMatchList)
	fits a transform to a std::list of Point pairs (p1,p2, the Point fields in StarMatch). More...
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...
std::string	__str__ ()
void	transformStar (FatPoint &in) const
virtual double	getJacobian (Point const &point) const
	returns the local jacobian. More...
virtual double	getJacobian (const double x, const double y) const
	returns the local jacobian. 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 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	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...
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::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

Detailed Description

This one is the Tangent Plane (called gnomonic) projection (from celestial sphere to tangent plane)

this transform does not implement corrections, since they are defined the other way around (from pixels to sky), and not invertible analytically. The inversion of tangent point WCS (TanPixelToRaDec) is obtained via inverseTransform().

Definition at line 703 of file AstrometryTransform.h.

Constructor & Destructor Documentation

TanRaDecToPixel() [1/2]

lsst::jointcal::TanRaDecToPixel::TanRaDecToPixel	(	AstrometryTransformLinear const &	tan2Pix,
		Point const &	tangentPoint
	)

assume degrees everywhere.

Definition at line 1631 of file AstrometryTransform.cc.

        : linTan2Pix(tan2Pix) {
    setTangentPoint(tangentPoint);
}

TanRaDecToPixel() [2/2]

lsst::jointcal::TanRaDecToPixel::TanRaDecToPixel

(

)

Definition at line 1645 of file AstrometryTransform.cc.

                                 : linTan2Pix() {
    ra0 = dec0 = 0;
    cos0 = 1;
    sin0 = 0;
}

Member Function Documentation

__str__()

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

inlineinherited

Definition at line 94 of file AstrometryTransform.h.

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

apply() [1/4]

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

inlineinherited

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); }

apply() [2/4]

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

inlineinherited

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() [3/4]

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

inherited

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 75 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() [4/4]

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

virtual

Implements lsst::jointcal::AstrometryTransform.

Definition at line 1708 of file AstrometryTransform.cc.

                                                                                                {
    double ra = deg2rad(xIn);
    double dec = deg2rad(yIn);
    if (ra - ra0 > M_PI) ra -= (2. * M_PI);
    if (ra - ra0 < -M_PI) ra += (2. * M_PI);
    // Code inspired from worldpos.c in wcssubs (ancestor of the wcslib)
    // The same code is copied in ::transformPosAndErrors()
    double coss = std::cos(dec);
    double sins = std::sin(dec);
    double l = std::sin(ra - ra0) * coss;
    double m = sins * sin0 + coss * cos0 * std::cos(ra - ra0);
    l = l / m;
    m = (sins * cos0 - coss * sin0 * std::cos(ra - ra0)) / m;
    // l and m are now coordinates in the tangent plane, in radians.
    l = rad2deg(l);
    m = rad2deg(m);
    linTan2Pix.apply(l, m, xOut, yOut);
}

clone()

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

virtual

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

Implements lsst::jointcal::AstrometryTransform.

Definition at line 1746 of file AstrometryTransform.cc.

                                                                {
    return std::unique_ptr<AstrometryTransform>(new TanRaDecToPixel(*this));
}

composeAndReduce()

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

virtualinherited

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 93 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

virtualinherited

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 117 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;
}

dump()

void lsst::jointcal::TanRaDecToPixel::dump ( std::ostream &  stream ) const

virtual

dumps the transform coefficients to stream.

Implements lsst::jointcal::AstrometryTransform.

Definition at line 1731 of file AstrometryTransform.cc.

                                                {
    Point tp = getTangentPoint();
    stream << " tan2pix " << linTan2Pix << " tangent point " << tp.x << ' ' << tp.y << endl;
}

fit()

double lsst::jointcal::TanRaDecToPixel::fit ( StarMatchList const &  starMatchList )

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.

Implements lsst::jointcal::AstrometryTransform.

Definition at line 1750 of file AstrometryTransform.cc.

                                                 {
    throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
                      "TanRaDecToPixel::fit is NOT implemented (although it is doable)) ");
    return -1;
}

getJacobian() [1/2]

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

inlinevirtualinherited

returns the local jacobian.

Definition at line 110 of file AstrometryTransform.h.

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

getJacobian() [2/2]

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

virtualinherited

returns the local jacobian.

Definition at line 98 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));
}

getLinPart()

AstrometryTransformLinear lsst::jointcal::TanRaDecToPixel::getLinPart

(

)

const

The Linear part (corresponding to CD's and CRPIX's)

Definition at line 1653 of file AstrometryTransform.cc.

{ return linTan2Pix; }

getNpar()

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

inlinevirtualinherited

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

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

Definition at line 180 of file AstrometryTransform.h.

{ return 0; }

getParams()

void lsst::jointcal::AstrometryTransform::getParams ( double *  params ) const

inherited

params should be at least Npar() long

Definition at line 215 of file AstrometryTransform.cc.

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

getTangentPoint()

Point lsst::jointcal::TanRaDecToPixel::getTangentPoint

(

)

const

tangent point coordinates (degrees)

Definition at line 1651 of file AstrometryTransform.cc.

{ return Point(rad2deg(ra0), rad2deg(dec0)); }

inverseTransform()

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

virtual

Inverse transform: returns a TanPixelToRaDec.

Reimplemented from lsst::jointcal::AstrometryTransform.

Definition at line 1741 of file AstrometryTransform.cc.

                                                                                                      {
    return std::unique_ptr<AstrometryTransform>(
            new TanPixelToRaDec(getLinPart().inverted(), getTangentPoint()));
}

inverted()

TanPixelToRaDec lsst::jointcal::TanRaDecToPixel::inverted

(

)

const

exact typed inverse:

Definition at line 1727 of file AstrometryTransform.cc.

                                                {
    return TanPixelToRaDec(getLinPart().inverted(), getTangentPoint());
}

linearApproximation()

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

virtualinherited

linear (local) approximation.

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

Definition at line 135 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 )

inherited

Definition at line 220 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

virtualinherited

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 235 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 ) const

virtualinherited

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial.

Definition at line 225 of file AstrometryTransform.cc.

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

paramRef() [2/2]

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

virtualinherited

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial.

Definition at line 230 of file AstrometryTransform.cc.

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

roughInverse()

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

virtual

Overload the "generic routine" (available for all AstrometryTransform types.

Reimplemented from lsst::jointcal::AstrometryTransform.

Definition at line 1736 of file AstrometryTransform.cc.

                                                                                    {
    return std::unique_ptr<AstrometryTransform>(
            new TanPixelToRaDec(getLinPart().inverted(), getTangentPoint()));
}

setTangentPoint()

void lsst::jointcal::TanRaDecToPixel::setTangentPoint

(

Point const &

tangentPoint

)

Resets the projection (or tangent) point.

Definition at line 1636 of file AstrometryTransform.cc.

                                                               {
    /* the radian to degrees conversion after projection
        is handled in apply */
    ra0 = deg2rad(tangentPoint.x);
    dec0 = deg2rad(tangentPoint.y);
    cos0 = std::cos(dec0);
    sin0 = std::sin(dec0);
}

toAstMap()

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

inlinevirtualinherited

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

virtualinherited

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

Definition at line 161 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::TanRaDecToPixel::transformPosAndErrors ( const FatPoint &  in, FatPoint &  out  ) const

virtual

transform with analytical derivatives

Reimplemented from lsst::jointcal::AstrometryTransform.

Definition at line 1656 of file AstrometryTransform.cc.

                                                                                   {
    /* this routine is very similar to apply, but also propagates errors.
       The deg2rad and rad2deg are ignored for errors because they act as
       2 global scalings that cancel each other.
       Derivatives were computed using maple:

       l1 := sin(a - a0)*cos(d);
       m1 := sin(d)*sin(d0)+cos(d)*cos(d0)*cos(a-a0);
       l2 := sin(d)*cos(d0)-cos(d)*sin(d0)*cos(a-a0);
       simplify(diff(l1/m1,a));
       simplify(diff(l1/m1,d));
       simplify(diff(l2/m1,a));
       simplify(diff(l2/m1,d));

       Checked against AstrometryTransform::transformPosAndErrors (dec 09)
    */
    double ra = deg2rad(in.x);
    double dec = deg2rad(in.y);
    if (ra - ra0 > M_PI) ra -= (2. * M_PI);
    if (ra - ra0 < -M_PI) ra += (2. * M_PI);
    // Code inspired from worldpos.c in wcssubs (ancestor of the wcslib)
    // The same code is copied in ::apply()

    double coss = std::cos(dec);
    double sins = std::sin(dec);
    double sinda = std::sin(ra - ra0);
    double cosda = std::cos(ra - ra0);
    double l = sinda * coss;
    double m = sins * sin0 + coss * cos0 * cosda;
    l = l / m;
    m = (sins * cos0 - coss * sin0 * cosda) / m;

    // derivatives
    double deno =
            sq(sin0) - sq(coss) + sq(coss * cos0) * (1 + sq(cosda)) + 2 * sins * sin0 * coss * cos0 * cosda;
    double a11 = coss * (cosda * sins * sin0 + coss * cos0) / deno;
    double a12 = -sinda * sin0 / deno;
    double a21 = coss * sinda * sins / deno;
    double a22 = cosda / deno;

    FatPoint tmp;
    tmp.vx = a11 * (a11 * in.vx + 2 * a12 * in.vxy) + a12 * a12 * in.vy;
    tmp.vy = a21 * a21 * in.vx + a22 * a22 * in.vy + 2. * a21 * a22 * in.vxy;
    tmp.vxy = a21 * a11 * in.vx + a22 * a12 * in.vy + (a21 * a12 + a11 * a22) * in.vxy;

    // l and m are now coordinates in the tangent plane, in radians.
    tmp.x = rad2deg(l);
    tmp.y = rad2deg(m);

    linTan2Pix.transformPosAndErrors(tmp, out);
}

transformStar()

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

inlineinherited

Definition at line 107 of file AstrometryTransform.h.

{ transformPosAndErrors(in, in); }

write() [1/2]

void lsst::jointcal::AstrometryTransform::write ( const std::string &  fileName ) const

inherited

Definition at line 245 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

virtualinherited

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

Definition at line 255 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/Linux64/jointcal/19.0.0-2-gb96a1c4+3/include/lsst/jointcal/AstrometryTransform.h
• /j/snowflake/release/lsstsw/stack/Linux64/jointcal/19.0.0-2-gb96a1c4+3/src/AstrometryTransform.cc