LSST Applications  21.0.0-172-gfb10e10a+18fedfabac,22.0.0+297cba6710,22.0.0+80564b0ff1,22.0.0+8d77f4f51a,22.0.0+a28f4c53b1,22.0.0+dcf3732eb2,22.0.1-1-g7d6de66+2a20fdde0d,22.0.1-1-g8e32f31+297cba6710,22.0.1-1-geca5380+7fa3b7d9b6,22.0.1-12-g44dc1dc+2a20fdde0d,22.0.1-15-g6a90155+515f58c32b,22.0.1-16-g9282f48+790f5f2caa,22.0.1-2-g92698f7+dcf3732eb2,22.0.1-2-ga9b0f51+7fa3b7d9b6,22.0.1-2-gd1925c9+bf4f0e694f,22.0.1-24-g1ad7a390+a9625a72a8,22.0.1-25-g5bf6245+3ad8ecd50b,22.0.1-25-gb120d7b+8b5510f75f,22.0.1-27-g97737f7+2a20fdde0d,22.0.1-32-gf62ce7b1+aa4237961e,22.0.1-4-g0b3f228+2a20fdde0d,22.0.1-4-g243d05b+871c1b8305,22.0.1-4-g3a563be+32dcf1063f,22.0.1-4-g44f2e3d+9e4ab0f4fa,22.0.1-42-gca6935d93+ba5e5ca3eb,22.0.1-5-g15c806e+85460ae5f3,22.0.1-5-g58711c4+611d128589,22.0.1-5-g75bb458+99c117b92f,22.0.1-6-g1c63a23+7fa3b7d9b6,22.0.1-6-g50866e6+84ff5a128b,22.0.1-6-g8d3140d+720564cf76,22.0.1-6-gd805d02+cc5644f571,22.0.1-8-ge5750ce+85460ae5f3,master-g6e05de7fdc+babf819c66,master-g99da0e417a+8d77f4f51a,w.2021.48
LSST Data Management Base Package
Classes | Public Member Functions | List of all members
lsst::afw::geom::SipApproximation Class Referencefinal

A fitter and results class for approximating a general Transform in a form compatible with FITS WCS persistence. More...

#include <SipApproximation.h>

Classes

struct  Grid
 
struct  Solution
 

Public Member Functions

 SipApproximation (std::shared_ptr< TransformPoint2ToPoint2 > pixelToIwc, lsst::geom::Point2D const &crpix, Eigen::Matrix2d const &cd, lsst::geom::Box2D const &bbox, lsst::geom::Extent2I const &gridShape, int order, bool useInverse=true, double svdThreshold=-1)
 Construct a new approximation by fitting on a grid of points. More...
 
 SipApproximation (std::shared_ptr< TransformPoint2ToPoint2 > pixelToIwc, lsst::geom::Point2D const &crpix, Eigen::Matrix2d const &cd, lsst::geom::Box2D const &bbox, lsst::geom::Extent2I const &gridShape, ndarray::Array< double const, 2 > const &a, ndarray::Array< double const, 2 > const &b, ndarray::Array< double const, 2 > const &ap, ndarray::Array< double const, 2 > const &bp, bool useInverse=true)
 Construct from existing SIP coefficients. More...
 
 SipApproximation (SipApproximation const &)=delete
 
SipApproximationoperator= (SipApproximation const &)=delete
 
 SipApproximation (SipApproximation &&) noexcept=default
 
SipApproximationoperator= (SipApproximation &&) noexcept=default
 
 ~SipApproximation () noexcept
 
int getOrder () const noexcept
 Return the polynomial order of the current solution (same for forward and reverse). More...
 
double getA (int p, int q) const
 Return a coefficient of the forward transform polynomial. More...
 
double getB (int p, int q) const
 Return a coefficient of the forward transform polynomial. More...
 
double getAP (int p, int q) const
 Return a coefficient of the reverse transform polynomial. More...
 
double getBP (int p, int q) const
 Return a coefficient of the reverse transform polynomial. More...
 
Eigen::MatrixXd getA () const noexcept
 Return the coefficients of the forward transform polynomial. More...
 
Eigen::MatrixXd getB () const noexcept
 Return the coefficients of the forward transform polynomial. More...
 
Eigen::MatrixXd getAP () const noexcept
 Return the coefficients of the reverse transform polynomial. More...
 
Eigen::MatrixXd getBP () const noexcept
 Return the coefficients of the reverse transform polynomial. More...
 
lsst::geom::Point2D applyForward (lsst::geom::Point2D const &pix) const
 Convert a point from pixels to intermediate world coordinates. More...
 
std::vector< lsst::geom::Point2DapplyForward (std::vector< lsst::geom::Point2D > const &pix) const
 Convert an array of points from pixels to intermediate world coordinates. More...
 
lsst::geom::Point2D applyInverse (lsst::geom::Point2D const &iwcs) const
 Convert a point from intermediate world coordinates to pixels. More...
 
std::vector< lsst::geom::Point2DapplyInverse (std::vector< lsst::geom::Point2D > const &iwcs) const
 Convert an array of points from intermediate world coordinates to pixels. More...
 
lsst::geom::Extent2D getGridStep () const noexcept
 Return the distance between grid points in pixels. More...
 
lsst::geom::Extent2I getGridShape () const noexcept
 Return the number of grid points in x and y. More...
 
lsst::geom::Box2D getBBox () const noexcept
 Return the pixel-coordinate bounding box over which the approximation should be valid. More...
 
lsst::geom::Point2D getPixelOrigin () const noexcept
 Return the pixel origin of the WCS being approximated. More...
 
Eigen::Matrix2d getCdMatrix () const noexcept
 Return the CD matrix of the WCS being approximated. More...
 
void updateGrid (lsst::geom::Extent2I const &shape)
 Update the grid to the given number of points in x and y. More...
 
void refineGrid (int factor=2)
 Update the grid by making it finer by a given integer factor. More...
 
void fit (int order, double svdThreshold=-1)
 Obtain a new solution at the given order with the current grid. More...
 
std::pair< double, double > computeMaxDeviation () const noexcept
 Return the maximum deviation of the solution from the exact transform on the current grid. More...
 

Detailed Description

A fitter and results class for approximating a general Transform in a form compatible with FITS WCS persistence.

The Simple Imaging Polynomial (SIP) convention (Shupe et al 2005) adds forward and reverse polynomial mappings to a standard projection FITS WCS projection (e.g. "TAN" for gnomonic) that relate Intermediate World Coordinates (see Calabretta & Greisen 2002) to image pixel coordinates. The SIP "forward" transform is defined by polynomial coeffients \(A\) and \(B\) that map pixel coordinates \((u, v)\) to Intermediate World Coordinates \((x, y)\) via

\[ \boldsymbol{S}\left[\begin{array}{c} x \\ y \end{array}\right] \equiv \left[\begin{array}{c} x_s \\ y_s \end{array}\right] = \left[\begin{array}{c} (u - u_0) + \displaystyle\sum_{p,q}^{0 \le p + q \le N} \mathrm{A}_{p,q} (u - u_0)^p (v - v_0)^q \\ (v - v_0) + \displaystyle\sum_{p,q}^{0 \le p + q \le N} \mathrm{B}_{p,q} (u - u_0)^p (v - v_0)^q \end{array}\right] \]

The reverse transform has essentially the same form:

\[ \left[\begin{array}{c} u - u_0 \\ v - v_0 \end{array}\right] = \left[\begin{array}{c} x_s + \displaystyle\sum_{p,q}^{0 \le p + q \le N} \mathrm{AP}_{p,q} x_s^p y_s^q \\ y_s + \displaystyle\sum_{p,q}^{0 \le p + q \le N} \mathrm{BP}_{p,q} x_s^p y_s^q \end{array}\right] \]

In both cases, \((u_0, v_0)\) is the pixel origin (CRPIX in FITS WCS) and \(\boldsymbol{S}\) is the inverse of the Jacobian "CD" matrix. Both CRPIX and CD are considered fixed inputs, and we do not attempt to null the zeroth- and first-order terms of \(A\) and \(B\) (as some SIP fitters do); together, these conventions make solving for the coefficients a much simpler linear problem.

Note
In the implementation, we typically refer to \((u-u_0, v-v_0)\) as dpix (for "pixel delta"), and \((x_s, y_s)\) as siwc (for "scaled intermediate world coordinates").

While LSST WCSs are in general too complex to be described exactly in FITS WCS, they can generally be closely approximated by standard FITS WCS projection with additional SIP distortions. This class fits such an approximation, given a TransformPoint2ToPoint2 object that represents the exact mapping from pixels to Intermediate World Coordinates with a SIP distortion.

Definition at line 94 of file SipApproximation.h.

Constructor & Destructor Documentation

◆ SipApproximation() [1/4]

lsst::afw::geom::SipApproximation::SipApproximation ( std::shared_ptr< TransformPoint2ToPoint2 pixelToIwc,
lsst::geom::Point2D const &  crpix,
Eigen::Matrix2d const &  cd,
lsst::geom::Box2D const &  bbox,
lsst::geom::Extent2I const &  gridShape,
int  order,
bool  useInverse = true,
double  svdThreshold = -1 
)

Construct a new approximation by fitting on a grid of points.

Parameters
[in]pixelToIwcThe true Transform to approximate. Should go from pixels to Intermediate World Coordinates when applyForward is called.
[in]crpixPixel origin, using the LSST 0-indexed convention rather than the FITS 1-indexed convention; equal to (CRPIX1 - 1, CRPIX2 - 1).
[in]cdNominal Jacobian ("CD" in FITS WCS).
[in]bboxPixel-coordinate bounding box over which the approximation should be valid. Used to construct the grid of points to fit.
[in]gridShapeNumber of points in x and y for the grid of points.
[in]orderOrder of the polynomial (same for forward and reverse transforms).
[in]useInverseIf true, the inverse SIP transform will be fit and compared to data points generated by calls to pixelToIwc.applyInverse instead of pixelToIwc.applyForward.
[in]svdThresholdFraction of the largest singular value at which to declare smaller singular values zero in the least squares solution. Negative values use Eigen's internal default.
Exceptions
lsst::pex::exceptions::InvalidParameterErrorThrown if order is negative or gridShape is non-positive.
Exception Safety
strong

Definition at line 209 of file SipApproximation.cc.

218  :
219  _useInverse(useInverse),
220  _pixelToIwc(std::move(pixelToIwc)),
221  _bbox(bbox),
222  _crpix(crpix),
223  _cdInv(lsst::geom::LinearTransform(cd).inverted()),
224  _grid(new Grid(gridShape, *this)),
225  _solution(Solution::fit(order, svdThreshold, *this))
226 {}
AmpInfoBoxKey bbox
Definition: Amplifier.cc:117
table::PointKey< double > crpix
Definition: OldWcs.cc:129
table::Key< table::Array< double > > cd
Definition: OldWcs.cc:130
A 2D linear coordinate transformation.
T move(T... args)
static std::unique_ptr< Solution > fit(int order_, double svdThreshold, SipApproximation const &parent)
table::Key< int > order

◆ SipApproximation() [2/4]

lsst::afw::geom::SipApproximation::SipApproximation ( std::shared_ptr< TransformPoint2ToPoint2 pixelToIwc,
lsst::geom::Point2D const &  crpix,
Eigen::Matrix2d const &  cd,
lsst::geom::Box2D const &  bbox,
lsst::geom::Extent2I const &  gridShape,
ndarray::Array< double const, 2 > const &  a,
ndarray::Array< double const, 2 > const &  b,
ndarray::Array< double const, 2 > const &  ap,
ndarray::Array< double const, 2 > const &  bp,
bool  useInverse = true 
)

Construct from existing SIP coefficients.

This constructor is primarily intended for testing purposes.

Parameters
[in]pixelToIwcThe true Transform to approximate. Should go from pixels to Intermediate World Coordinates when applyForward is called.
[in]crpixPixel origin, using the LSST 0-indexed convention rather than the FITS 1-indexed convention; equal to (CRPIX1 - 1, CRPIX - 1).
[in]cdNominal Jacobian ("CD" in FITS WCS).
[in]bboxPixel-coordinate bounding box over which the approximation should be valid. Used to construct the grid of points to fit.
[in]gridShapeNumber of points in x and y for the grid of points.
[in]aMatrix of A coefficients, with the first dimension corresponding to powers of \((u - u_0)\) and the second corresponding to powers of \((v - v_0)\).
[in]bMatrix of B coefficients, with the first dimension corresponding to powers of \((u - u_0)\) and the second corresponding to powers of \((v - v_0)\).
[in]apMatrix of AP coefficients, with the first dimension corresponding to powers of \(x_s\) and the second corresponding to powers of \(y_s\).
[in]bpMatrix of BP coefficients, with the first dimension corresponding to powers of \(x_s\) and the second corresponding to powers of \(y_s\).
[in]useInverseIf true, the inverse SIP transform will be compared to data points generated by calls to pixelToIwc.applyInverse instead of pixelToIwc.applyForward.
Exceptions
lsst::pex::exceptions::InvalidParameterErrorThrown if gridShape is non-positive, or any matrix argument is non-square.
Exception Safety
strong

Definition at line 228 of file SipApproximation.cc.

239  :
240  _useInverse(useInverse),
241  _pixelToIwc(std::move(pixelToIwc)),
242  _bbox(bbox),
243  _crpix(crpix),
244  _cdInv(lsst::geom::LinearTransform(cd).inverted()),
245  _grid(new Grid(gridShape, *this)),
246  _solution(
247  new Solution(
248  makePolynomialFromCoeffMatrix(a),
249  makePolynomialFromCoeffMatrix(b),
250  makePolynomialFromCoeffMatrix(ap),
251  makePolynomialFromCoeffMatrix(bp)
252  )
253  )
254 {}
table::Key< int > b
table::Key< int > a

◆ SipApproximation() [3/4]

lsst::afw::geom::SipApproximation::SipApproximation ( SipApproximation const &  )
delete

◆ SipApproximation() [4/4]

lsst::afw::geom::SipApproximation::SipApproximation ( SipApproximation &&  )
defaultnoexcept

◆ ~SipApproximation()

lsst::afw::geom::SipApproximation::~SipApproximation ( )
defaultnoexcept

Member Function Documentation

◆ applyForward() [1/2]

lsst::geom::Point2D lsst::afw::geom::SipApproximation::applyForward ( lsst::geom::Point2D const &  pix) const

Convert a point from pixels to intermediate world coordinates.

This method is inefficient and should only be used for diagnostic purposes.

Exception Safety
strong

Definition at line 321 of file SipApproximation.cc.

321  {
322  auto cd = _cdInv.inverted();
323  auto ws = _solution->makeWorkspace();
324  return cd(_solution->applyForward(pix - _crpix, ws));
325 }
LinearTransform const inverted() const
Return the inverse transform.
T ws(T... args)

◆ applyForward() [2/2]

std::vector< lsst::geom::Point2D > lsst::afw::geom::SipApproximation::applyForward ( std::vector< lsst::geom::Point2D > const &  pix) const

Convert an array of points from pixels to intermediate world coordinates.

Exception Safety
strong

Definition at line 327 of file SipApproximation.cc.

328  {
329  auto ws = _solution->makeWorkspace();
331  iwc.reserve(pix.size());
332  auto cd = _cdInv.inverted();
333  for (auto const & point : pix) {
334  iwc.push_back(cd(_solution->applyForward(point - _crpix, ws)));
335  }
336  return iwc;
337 }
T push_back(T... args)
T reserve(T... args)
T size(T... args)

◆ applyInverse() [1/2]

lsst::geom::Point2D lsst::afw::geom::SipApproximation::applyInverse ( lsst::geom::Point2D const &  iwcs) const

Convert a point from intermediate world coordinates to pixels.

This method is inefficient and should only be used for diagnostic purposes.

Exception Safety
strong

Definition at line 339 of file SipApproximation.cc.

339  {
340  auto ws = _solution->makeWorkspace();
341  return _solution->applyInverse(_cdInv(iwc), ws) + _crpix;
342 }

◆ applyInverse() [2/2]

std::vector< lsst::geom::Point2D > lsst::afw::geom::SipApproximation::applyInverse ( std::vector< lsst::geom::Point2D > const &  iwcs) const

Convert an array of points from intermediate world coordinates to pixels.

Exception Safety
strong

Definition at line 344 of file SipApproximation.cc.

345  {
346  auto ws = _solution->makeWorkspace();
348  pix.reserve(iwc.size());
349  for (auto const & point : iwc) {
350  pix.push_back(_solution->applyInverse(_cdInv(point), ws) + _crpix);
351  }
352  return pix;
353 }

◆ computeMaxDeviation()

std::pair< double, double > lsst::afw::geom::SipApproximation::computeMaxDeviation ( ) const
noexcept

Return the maximum deviation of the solution from the exact transform on the current grid.

The deviations are in scaled intermediate world coordinates \(\sqrt{\delta x_s^2 \delta y_s^2}\) for the forward transform and in pixels \((\delta u^2, \delta v^2)\) for the reverse transform (respectively). Note that in the common case where the CD matrix includes the scaling from angle units to pixel units, the scaled intermediate world coordinate values are also in (nominal) pixel units.

Definition at line 380 of file SipApproximation.cc.

380  {
381  std::pair<double, double> maxDiff(0.0, 0.0);
382  auto ws = _solution->makeWorkspace();
383  for (std::size_t i = 0; i < _grid->dpix1.size(); ++i) {
384  auto siwc2 = _solution->applyForward(_grid->dpix1[i], ws);
385  auto dpix2 = _solution->applyInverse(_grid->siwc[i], ws);
386  maxDiff.first = std::max(maxDiff.first, (_grid->siwc[i] - siwc2).computeNorm());
387  maxDiff.second = std::max(maxDiff.second, (_grid->dpix2[i] - dpix2).computeNorm());
388  }
389  return maxDiff;
390 }
T max(T... args)

◆ fit()

void lsst::afw::geom::SipApproximation::fit ( int  order,
double  svdThreshold = -1 
)

Obtain a new solution at the given order with the current grid.

Parameters
[in]orderPolynomial order to fit.
[in]svdThresholdFraction of the largest singular value at which to declare smaller singular values zero in the least squares solution. Negative values use Eigen's internal default.
Exceptions
pex::exceptions::LogicErrorThrown if the number of free parameters implied by order is larger than the number of data points defined by the grid.
Exception Safety
strong

Definition at line 376 of file SipApproximation.cc.

376  {
377  _solution = Solution::fit(order, svdThreshold, *this);
378 }

◆ getA() [1/2]

Eigen::MatrixXd lsst::afw::geom::SipApproximation::getA ( ) const
noexcept

Return the coefficients of the forward transform polynomial.

Definition at line 293 of file SipApproximation.cc.

293  {
294  return makeCoefficientMatrix(
295  getOrder(),
296  [this](int p, int q) { return getA(p, q); }
297  );
298 }
Eigen::MatrixXd getA() const noexcept
Return the coefficients of the forward transform polynomial.
int getOrder() const noexcept
Return the polynomial order of the current solution (same for forward and reverse).

◆ getA() [2/2]

double lsst::afw::geom::SipApproximation::getA ( int  p,
int  q 
) const

Return a coefficient of the forward transform polynomial.

Out-of-bounds arguments yields undefined behavior.

Exception Safety
strong

Definition at line 262 of file SipApproximation.cc.

262  {
263  return _solution->a[_solution->a.getBasis().index(p, q)];
264 }

◆ getAP() [1/2]

Eigen::MatrixXd lsst::afw::geom::SipApproximation::getAP ( ) const
noexcept

Return the coefficients of the reverse transform polynomial.

Definition at line 307 of file SipApproximation.cc.

307  {
308  return makeCoefficientMatrix(
309  getOrder(),
310  [this](int p, int q) { return getAP(p, q); }
311  );
312 }
Eigen::MatrixXd getAP() const noexcept
Return the coefficients of the reverse transform polynomial.

◆ getAP() [2/2]

double lsst::afw::geom::SipApproximation::getAP ( int  p,
int  q 
) const

Return a coefficient of the reverse transform polynomial.

Out-of-bounds arguments yields undefined behavior.

Exception Safety
strong

Definition at line 270 of file SipApproximation.cc.

270  {
271  return _solution->ap[_solution->ap.getBasis().index(p, q)];
272 }

◆ getB() [1/2]

Eigen::MatrixXd lsst::afw::geom::SipApproximation::getB ( ) const
noexcept

Return the coefficients of the forward transform polynomial.

Definition at line 300 of file SipApproximation.cc.

300  {
301  return makeCoefficientMatrix(
302  getOrder(),
303  [this](int p, int q) { return getB(p, q); }
304  );
305 }
Eigen::MatrixXd getB() const noexcept
Return the coefficients of the forward transform polynomial.

◆ getB() [2/2]

double lsst::afw::geom::SipApproximation::getB ( int  p,
int  q 
) const

Return a coefficient of the forward transform polynomial.

Out-of-bounds arguments yields undefined behavior.

Exception Safety
strong

Definition at line 266 of file SipApproximation.cc.

266  {
267  return _solution->b[_solution->b.getBasis().index(p, q)];
268 }

◆ getBBox()

lsst::geom::Box2D lsst::afw::geom::SipApproximation::getBBox ( ) const
inlinenoexcept

Return the pixel-coordinate bounding box over which the approximation should be valid.

Definition at line 291 of file SipApproximation.h.

291 { return _bbox; }

◆ getBP() [1/2]

Eigen::MatrixXd lsst::afw::geom::SipApproximation::getBP ( ) const
noexcept

Return the coefficients of the reverse transform polynomial.

Definition at line 314 of file SipApproximation.cc.

314  {
315  return makeCoefficientMatrix(
316  getOrder(),
317  [this](int p, int q) { return getBP(p, q); }
318  );
319 }
Eigen::MatrixXd getBP() const noexcept
Return the coefficients of the reverse transform polynomial.

◆ getBP() [2/2]

double lsst::afw::geom::SipApproximation::getBP ( int  p,
int  q 
) const

Return a coefficient of the reverse transform polynomial.

Out-of-bounds arguments yields undefined behavior.

Exception Safety
strong

Definition at line 274 of file SipApproximation.cc.

274  {
275  return _solution->bp[_solution->bp.getBasis().index(p, q)];
276 }

◆ getCdMatrix()

Eigen::Matrix2d lsst::afw::geom::SipApproximation::getCdMatrix ( ) const
inlinenoexcept

Return the CD matrix of the WCS being approximated.

Definition at line 297 of file SipApproximation.h.

297 { return _cdInv.inverted().getMatrix(); }
Matrix const & getMatrix() const noexcept

◆ getGridShape()

lsst::geom::Extent2I lsst::afw::geom::SipApproximation::getGridShape ( ) const
noexcept

Return the number of grid points in x and y.

Definition at line 360 of file SipApproximation.cc.

360  {
361  return _grid->shape;
362 }

◆ getGridStep()

lsst::geom::Extent2D lsst::afw::geom::SipApproximation::getGridStep ( ) const
noexcept

Return the distance between grid points in pixels.

Definition at line 355 of file SipApproximation.cc.

355  {
356  return lsst::geom::Extent2D(_bbox.getWidth()/_grid->shape.getX(),
357  _bbox.getHeight()/_grid->shape.getY());
358 }
double getWidth() const noexcept
1-d interval accessors
Definition: Box.h:529
double getHeight() const noexcept
1-d interval accessors
Definition: Box.h:530
Extent< double, 2 > Extent2D
Definition: Extent.h:400

◆ getOrder()

int lsst::afw::geom::SipApproximation::getOrder ( ) const
noexcept

Return the polynomial order of the current solution (same for forward and reverse).

Definition at line 258 of file SipApproximation.cc.

258  {
259  return _solution->a.getBasis().getOrder();
260 }

◆ getPixelOrigin()

lsst::geom::Point2D lsst::afw::geom::SipApproximation::getPixelOrigin ( ) const
inlinenoexcept

Return the pixel origin of the WCS being approximated.

Definition at line 294 of file SipApproximation.h.

294 { return lsst::geom::Point2D(_crpix); }
Point< double, 2 > Point2D
Definition: Point.h:324

◆ operator=() [1/2]

SipApproximation& lsst::afw::geom::SipApproximation::operator= ( SipApproximation &&  )
defaultnoexcept

◆ operator=() [2/2]

SipApproximation& lsst::afw::geom::SipApproximation::operator= ( SipApproximation const &  )
delete

◆ refineGrid()

void lsst::afw::geom::SipApproximation::refineGrid ( int  factor = 2)

Update the grid by making it finer by a given integer factor.

Exceptions
lsst::pex::exceptions::InvalidParameterErrorThrown if factor is non-positive.
Exception Safety
strong

Definition at line 368 of file SipApproximation.cc.

368  {
369  // We shrink the grid spacing by the given factor, which is not the same
370  // as increasing the number of grid points by that factor, because there
371  // is one more grid point that step in each dimension.
372  lsst::geom::Extent2I unit(1);
373  updateGrid((_grid->shape - unit)*f + unit);
374 }
void updateGrid(lsst::geom::Extent2I const &shape)
Update the grid to the given number of points in x and y.

◆ updateGrid()

void lsst::afw::geom::SipApproximation::updateGrid ( lsst::geom::Extent2I const &  shape)

Update the grid to the given number of points in x and y.

This does not invalidate or modify the current solution; this allows the user to fit with a coarse grid and then check whether the solution still works well on a finer grid.

Exceptions
lsst::pex::exceptions::InvalidParameterErrorThrown if shape is non-positive.
Exception Safety
strong

Definition at line 364 of file SipApproximation.cc.

364  {
365  _grid = std::make_unique<Grid>(shape, *this);
366 }

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