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LSST Data Management Base Package
Public Member Functions | List of all members
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:
lsst::jointcal::AstrometryTransform

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< AstrometryTransformroughInverse (const Frame &region) const
 Overload the "generic routine" (available for all AstrometryTransform types. More...
 
std::unique_ptr< AstrometryTransforminverseTransform (const double precision, const Frame &region) const
 Inverse transform: returns a TanPixelToRaDec. More...
 
void print (std::ostream &out) const
 prints the transform coefficients to stream. More...
 
std::unique_ptr< AstrometryTransformclone () 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...
 
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...
 
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< AstrometryTransformcomposeAndReduce (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::MappingtoAstMap (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 707 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 1660 of file AstrometryTransform.cc.

1661  : linTan2Pix(tan2Pix) {
1662  setTangentPoint(tangentPoint);
1663 }
void setTangentPoint(Point const &tangentPoint)
Resets the projection (or tangent) point.

◆ TanRaDecToPixel() [2/2]

lsst::jointcal::TanRaDecToPixel::TanRaDecToPixel ( )

Definition at line 1674 of file AstrometryTransform.cc.

1674  : linTan2Pix() {
1675  ra0 = dec0 = 0;
1676  cos0 = 1;
1677  sin0 = 0;
1678 }

Member Function Documentation

◆ __str__()

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

Definition at line 94 of file AstrometryTransform.h.

94  {
96  print(s);
97  return s.str();
98  }
virtual void print(std::ostream &out) const =0
prints the transform coefficients to stream.
T str(T... args)

◆ apply() [1/8]

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

Implements lsst::jointcal::AstrometryTransform.

Definition at line 1737 of file AstrometryTransform.cc.

1737  {
1738  double ra = deg2rad(xIn);
1739  double dec = deg2rad(yIn);
1740  if (ra - ra0 > M_PI) ra -= (2. * M_PI);
1741  if (ra - ra0 < -M_PI) ra += (2. * M_PI);
1742  // Code inspired from worldpos.c in wcssubs (ancestor of the wcslib)
1743  // The same code is copied in ::transformPosAndErrors()
1744  double coss = std::cos(dec);
1745  double sins = std::sin(dec);
1746  double l = std::sin(ra - ra0) * coss;
1747  double m = sins * sin0 + coss * cos0 * std::cos(ra - ra0);
1748  l = l / m;
1749  m = (sins * cos0 - coss * sin0 * std::cos(ra - ra0)) / m;
1750  // l and m are now coordinates in the tangent plane, in radians.
1751  l = rad2deg(l);
1752  m = rad2deg(m);
1753  linTan2Pix.apply(l, m, xOut, yOut);
1754 }
#define M_PI
Definition: ListMatch.cc:31
double dec
Definition: Match.cc:41
int m
Definition: SpanSet.cc:48
void apply(const double xIn, const double yIn, double &xOut, double &yOut) const override
T cos(T... args)
T sin(T... args)

◆ apply() [2/8]

virtual void lsst::jointcal::AstrometryTransform::apply

◆ apply() [3/8]

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]inputframeThe frame to be transformed.
[in]inscribedReturn the inscribed (true) or circumscribed (false) box.
Returns
The transformed frame.

Definition at line 76 of file AstrometryTransform.cc.

76  {
77  // 2 opposite corners
78  double xtmin1, xtmax1, ytmin1, ytmax1;
79  apply(inputframe.xMin, inputframe.yMin, xtmin1, ytmin1);
80  apply(inputframe.xMax, inputframe.yMax, xtmax1, ytmax1);
81  Frame fr1(std::min(xtmin1, xtmax1), std::min(ytmin1, ytmax1), std::max(xtmin1, xtmax1),
82  std::max(ytmin1, ytmax1));
83  // 2 other corners
84  double xtmin2, xtmax2, ytmin2, ytmax2;
85  apply(inputframe.xMin, inputframe.yMax, xtmin2, ytmax2);
86  apply(inputframe.xMax, inputframe.yMin, xtmax2, ytmin2);
87  Frame fr2(std::min(xtmin2, xtmax2), std::min(ytmin2, ytmax2), std::max(xtmin2, xtmax2),
88  std::max(ytmin2, ytmax2));
89 
90  if (inscribed) return fr1 * fr2;
91  return fr1 + fr2;
92 }
virtual void apply(const double xIn, const double yIn, double &xOut, double &yOut) const =0
T max(T... args)
T min(T... args)

◆ apply() [4/8]

Frame lsst::jointcal::AstrometryTransform::apply

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

Parameters
[in]inputframeThe frame to be transformed.
[in]inscribedReturn the inscribed (true) or circumscribed (false) box.
Returns
The transformed frame.

Definition at line 89 of file AstrometryTransform.cc.

76  {
77  // 2 opposite corners
78  double xtmin1, xtmax1, ytmin1, ytmax1;
79  apply(inputframe.xMin, inputframe.yMin, xtmin1, ytmin1);
80  apply(inputframe.xMax, inputframe.yMax, xtmax1, ytmax1);
81  Frame fr1(std::min(xtmin1, xtmax1), std::min(ytmin1, ytmax1), std::max(xtmin1, xtmax1),
82  std::max(ytmin1, ytmax1));
83  // 2 other corners
84  double xtmin2, xtmax2, ytmin2, ytmax2;
85  apply(inputframe.xMin, inputframe.yMax, xtmin2, ytmax2);
86  apply(inputframe.xMax, inputframe.yMin, xtmax2, ytmin2);
87  Frame fr2(std::min(xtmin2, xtmax2), std::min(ytmin2, ytmax2), std::max(xtmin2, xtmax2),
88  std::max(ytmin2, ytmax2));
89 
90  if (inscribed) return fr1 * fr2;
91  return fr1 + fr2;
92 }
virtual void apply(const double xIn, const double yIn, double &xOut, double &yOut) const=0

◆ apply() [5/8]

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.

75  {
76  double xout, yout;
77  apply(in.x, in.y, xout, yout);
78  return Point(xout, yout);
79  }

◆ apply() [6/8]

Point lsst::jointcal::AstrometryTransform::apply
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.

75  {
76  double xout, yout;
77  apply(in.x, in.y, xout, yout);
78  return Point(xout, yout);
79  }

◆ apply() [7/8]

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.

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

◆ apply() [8/8]

void lsst::jointcal::AstrometryTransform::apply
inline

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

Definition at line 71 of file AstrometryTransform.h.

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

◆ 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 1776 of file AstrometryTransform.cc.

◆ 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
rightThe 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.

95  { // by default no way to compose
97 }

◆ 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 118 of file AstrometryTransform.cc.

119  {
120  double x = where.x;
121  double y = where.y;
122  double xp0, yp0;
123  apply(x, y, xp0, yp0);
124 
125  double xp, yp;
126  apply(x + step, y, xp, yp);
127  derivative.a11() = (xp - xp0) / step;
128  derivative.a21() = (yp - yp0) / step;
129  apply(x, y + step, xp, yp);
130  derivative.a12() = (xp - xp0) / step;
131  derivative.a22() = (yp - yp0) / step;
132  derivative.dx() = 0;
133  derivative.dy() = 0;
134 }
int const step
double x
int y
Definition: SpanSet.cc:48

◆ 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 1780 of file AstrometryTransform.cc.

1780  {
1781  throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
1782  "TanRaDecToPixel::fit is NOT implemented (although it is doable)) ");
1783  return -1;
1784 }
#define LSST_EXCEPT(type,...)
Create an exception with a given type.
Definition: Exception.h:48

◆ getJacobian() [1/2]

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

returns the local jacobian.

Definition at line 99 of file AstrometryTransform.cc.

99  {
100  double x2, y2;
101  double eps = x * 0.01;
102  if (eps == 0) eps = 0.01;
103  apply(x, y, x2, y2);
104  double dxdx, dydx;
105  apply(x + eps, y, dxdx, dydx);
106  dxdx -= x2;
107  dydx -= y2;
108  double dxdy, dydy;
109  apply(x, y + eps, dxdy, dydy);
110  dxdy -= x2;
111  dydy -= y2;
112  return ((dxdx * dydy - dxdy * dydx) / (eps * eps));
113 }

◆ getJacobian() [2/2]

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

returns the local jacobian.

Definition at line 110 of file AstrometryTransform.h.

110 { return getJacobian(point.x, point.y); }
virtual double getJacobian(Point const &point) const
returns the local jacobian.

◆ getLinPart()

AstrometryTransformLinear lsst::jointcal::TanRaDecToPixel::getLinPart ( ) const

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

Definition at line 1682 of file AstrometryTransform.cc.

1682 { return linTan2Pix; }

◆ getNpar()

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

◆ getParams()

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

params should be at least Npar() long

Definition at line 216 of file AstrometryTransform.cc.

216  {
217  std::size_t npar = getNpar();
218  for (std::size_t i = 0; i < npar; ++i) params[i] = paramRef(i);
219 }
virtual double paramRef(Eigen::Index const i) const
virtual std::size_t getNpar() const
returns the number of parameters (to compute chi2's)

◆ getTangentPoint()

Point lsst::jointcal::TanRaDecToPixel::getTangentPoint ( ) const

tangent point coordinates (degrees)

Definition at line 1680 of file AstrometryTransform.cc.

1680 { 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 1771 of file AstrometryTransform.cc.

1771  {
1773  new TanPixelToRaDec(getLinPart().inverted(), getTangentPoint()));
1774 }
Point getTangentPoint() const
tangent point coordinates (degrees)
TanPixelToRaDec inverted() const
exact typed inverse:
AstrometryTransformLinear getLinPart() const
The Linear part (corresponding to CD's and CRPIX's)

◆ inverted()

TanPixelToRaDec lsst::jointcal::TanRaDecToPixel::inverted ( ) const

exact typed inverse:

Definition at line 1756 of file AstrometryTransform.cc.

1756  {
1757  return TanPixelToRaDec(getLinPart().inverted(), getTangentPoint());
1758 }

◆ 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 136 of file AstrometryTransform.cc.

137  {
138  Point outwhere = apply(where);
139  AstrometryTransformLinear der;
140  computeDerivative(where, der, step);
141  return AstrometryTransformLinearShift(outwhere.x, outwhere.y) * der *
142  AstrometryTransformLinearShift(-where.x, -where.y);
143 }
virtual void computeDerivative(Point const &where, AstrometryTransformLinear &derivative, const double step=0.01) const
Computes the local Derivative of a transform, w.r.t.

◆ offsetParams()

void lsst::jointcal::AstrometryTransform::offsetParams ( Eigen::VectorXd const &  delta)
inherited

Definition at line 221 of file AstrometryTransform.cc.

221  {
222  std::size_t npar = getNpar();
223  for (std::size_t i = 0; i < npar; ++i) paramRef(i) += delta[i];
224 }

◆ 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 236 of file AstrometryTransform.cc.

236  {
237  throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
238  "AstrometryTransform::paramDerivatives() should never be called ");
239 }

◆ paramRef() [1/2]

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

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial.

Definition at line 231 of file AstrometryTransform.cc.

231  {
232  throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
233  "AstrometryTransform::paramRef should never be called ");
234 }

◆ paramRef() [2/2]

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

Reimplemented in lsst::jointcal::AstrometryTransformPolynomial.

Definition at line 226 of file AstrometryTransform.cc.

226  {
227  throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
228  std::string("AstrometryTransform::paramRef should never be called "));
229 }

◆ print()

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

prints the transform coefficients to stream.

Implements lsst::jointcal::AstrometryTransform.

Definition at line 1760 of file AstrometryTransform.cc.

1760  {
1761  Point tp = getTangentPoint();
1762  stream << "tan2pix " << linTan2Pix << std::endl;
1763  stream << "tangent point " << tp.x << ' ' << tp.y << endl;
1764 }
T endl(T... args)

◆ 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 1766 of file AstrometryTransform.cc.

1766  {
1768  new TanPixelToRaDec(getLinPart().inverted(), getTangentPoint()));
1769 }

◆ setTangentPoint()

void lsst::jointcal::TanRaDecToPixel::setTangentPoint ( Point const &  tangentPoint)

Resets the projection (or tangent) point.

Definition at line 1665 of file AstrometryTransform.cc.

1665  {
1666  /* the radian to degrees conversion after projection
1667  is handled in apply */
1668  ra0 = deg2rad(tangentPoint.x);
1669  dec0 = deg2rad(tangentPoint.y);
1670  cos0 = std::cos(dec0);
1671  sin0 = std::sin(dec0);
1672 }

◆ 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
domainThe 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.

189  {
190  throw std::logic_error("toAstMap is not implemented for this class.");
191  }

◆ 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 162 of file AstrometryTransform.cc.

162  {
163  AstrometryTransformLinear der;
164  computeDerivative(where, der, 0.01);
165  double a11 = der.A11();
166  double a22 = der.A22();
167  double a21 = der.A21();
168  double a12 = der.A12();
169 
170  /* (a11 a12) (vxx vxy)
171  M = ( ) and V = ( )
172  (a21 a22) (xvy vyy)
173 
174  Vxx = Vin[0], vyy = Vin[1], Vxy = Vin[2];
175  we want to compute M*V*tp(M)
176  A lin alg light package would be perfect...
177  */
178  int xx = 0;
179  int yy = 1;
180  int xy = 2;
181  // M*V :
182 
183  double b11 = a11 * vIn[xx] + a12 * vIn[xy];
184  double b22 = a21 * vIn[xy] + a22 * vIn[yy];
185  double b12 = a11 * vIn[xy] + a12 * vIn[yy];
186  double b21 = a21 * vIn[xx] + a22 * vIn[xy];
187 
188  // (M*V) * tp(M)
189 
190  vOut[xx] = b11 * a11 + b12 * a12;
191  vOut[xy] = b11 * a21 + b12 * a22;
192  vOut[yy] = b21 * a21 + b22 * a22;
193 }

◆ 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 1685 of file AstrometryTransform.cc.

1685  {
1686  /* this routine is very similar to apply, but also propagates errors.
1687  The deg2rad and rad2deg are ignored for errors because they act as
1688  2 global scalings that cancel each other.
1689  Derivatives were computed using maple:
1690 
1691  l1 := sin(a - a0)*cos(d);
1692  m1 := sin(d)*sin(d0)+cos(d)*cos(d0)*cos(a-a0);
1693  l2 := sin(d)*cos(d0)-cos(d)*sin(d0)*cos(a-a0);
1694  simplify(diff(l1/m1,a));
1695  simplify(diff(l1/m1,d));
1696  simplify(diff(l2/m1,a));
1697  simplify(diff(l2/m1,d));
1698 
1699  Checked against AstrometryTransform::transformPosAndErrors (dec 09)
1700  */
1701  double ra = deg2rad(in.x);
1702  double dec = deg2rad(in.y);
1703  if (ra - ra0 > M_PI) ra -= (2. * M_PI);
1704  if (ra - ra0 < -M_PI) ra += (2. * M_PI);
1705  // Code inspired from worldpos.c in wcssubs (ancestor of the wcslib)
1706  // The same code is copied in ::apply()
1707 
1708  double coss = std::cos(dec);
1709  double sins = std::sin(dec);
1710  double sinda = std::sin(ra - ra0);
1711  double cosda = std::cos(ra - ra0);
1712  double l = sinda * coss;
1713  double m = sins * sin0 + coss * cos0 * cosda;
1714  l = l / m;
1715  m = (sins * cos0 - coss * sin0 * cosda) / m;
1716 
1717  // derivatives
1718  double deno =
1719  sq(sin0) - sq(coss) + sq(coss * cos0) * (1 + sq(cosda)) + 2 * sins * sin0 * coss * cos0 * cosda;
1720  double a11 = coss * (cosda * sins * sin0 + coss * cos0) / deno;
1721  double a12 = -sinda * sin0 / deno;
1722  double a21 = coss * sinda * sins / deno;
1723  double a22 = cosda / deno;
1724 
1725  FatPoint tmp;
1726  tmp.vx = a11 * (a11 * in.vx + 2 * a12 * in.vxy) + a12 * a12 * in.vy;
1727  tmp.vy = a21 * a21 * in.vx + a22 * a22 * in.vy + 2. * a21 * a22 * in.vxy;
1728  tmp.vxy = a21 * a11 * in.vx + a22 * a12 * in.vy + (a21 * a12 + a11 * a22) * in.vxy;
1729 
1730  // l and m are now coordinates in the tangent plane, in radians.
1731  tmp.x = rad2deg(l);
1732  tmp.y = rad2deg(m);
1733 
1734  linTan2Pix.transformPosAndErrors(tmp, out);
1735 }
virtual void transformPosAndErrors(const FatPoint &in, FatPoint &out) const override
a mix of apply and Derivative

◆ transformStar()

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

Definition at line 107 of file AstrometryTransform.h.

107 { transformPosAndErrors(in, in); }
virtual void transformPosAndErrors(const FatPoint &in, FatPoint &out) const

◆ write() [1/2]

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

Definition at line 246 of file AstrometryTransform.cc.

246  {
247  ofstream s(fileName.c_str());
248  write(s);
249  bool ok = !s.fail();
250  s.close();
251  if (!ok)
252  throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
253  "AstrometryTransform::write, something went wrong for file " + fileName);
254 }
T c_str(T... args)
void write(const std::string &fileName) const

◆ 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 256 of file AstrometryTransform.cc.

256  {
257  throw LSST_EXCEPT(
258  pex::exceptions::InvalidParameterError,
259  "AstrometryTransform::write(ostream), should never be called. MEans that it is missing in some "
260  "derived class ");
261 }

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