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
|
Class that handles the astrometric least squares problem. More...
#include <AstrometryFit.h>
Public Member Functions | |
AstrometryFit (std::shared_ptr< Associations > associations, std::shared_ptr< AstrometryModel > astrometryModel, double posError) | |
this is the only constructor More... | |
AstrometryFit (AstrometryFit const &)=delete | |
No copy or move: there is only ever one fitter of a given type. More... | |
AstrometryFit (AstrometryFit &&)=delete | |
AstrometryFit & | operator= (AstrometryFit const &)=delete |
AstrometryFit & | operator= (AstrometryFit &&)=delete |
void | assignIndices (std::string const &whatToFit) override |
Set parameters to fit and assign indices in the big matrix. More... | |
void | freezeErrorTransform () |
The transformations used to propagate errors are freezed to the current state. More... | |
void | offsetParams (Eigen::VectorXd const &delta) override |
Offset the parameters by the requested quantities. More... | |
std::shared_ptr< AstrometryModel > | getModel () const |
Return the model being fit. More... | |
void | checkStuff () |
DEBUGGING routine. More... | |
MinimizeResult | minimize (std::string const &whatToFit, double const nSigmaCut=0, double sigmaRelativeTolerance=0, bool const doRankUpdate=true, bool const doLineSearch=false, std::string const &dumpMatrixFile="") |
Does a 1 step minimization, assuming a linear model. More... | |
Chi2Statistic | computeChi2 () const |
Returns the chi2 for the current state. More... | |
void | leastSquareDerivatives (TripletList &tripletList, Eigen::VectorXd &grad) const |
Evaluates the chI^2 derivatives (Jacobian and gradient) for the current whatToFit setting. More... | |
virtual void | saveChi2Contributions (std::string const &baseName) const |
Save the full chi2 term per star that was used in the minimization, for debugging. More... | |
Protected Member Functions | |
void | saveChi2MeasContributions (std::string const &filename) const override |
Save a CSV file containing residuals of measurement terms. More... | |
void | saveChi2RefContributions (std::string const &filename) const override |
Save a CSV file containing residuals of reference terms. More... | |
std::size_t | findOutliers (double nSigmaCut, MeasuredStarList &msOutliers, FittedStarList &fsOutliers, double &cut) const |
Find Measurements and references contributing more than a cut, computed as. More... | |
void | outliersContributions (MeasuredStarList &msOutliers, FittedStarList &fsOutliers, TripletList &tripletList, Eigen::VectorXd &grad) |
Contributions to derivatives from (presumably) outlier terms. More... | |
void | removeMeasOutliers (MeasuredStarList &outliers) |
Remove measuredStar outliers from the fit. No Refit done. More... | |
void | removeRefOutliers (FittedStarList &outliers) |
Remove refStar outliers from the fit. No Refit done. More... | |
Protected Attributes | |
std::shared_ptr< Associations > | _associations |
std::string | _whatToFit |
Eigen::Index | _lastNTrip |
Eigen::Index | _nTotal |
Eigen::Index | _nModelParams |
Eigen::Index | _nStarParams |
LOG_LOGGER | _log |
Class that handles the astrometric least squares problem.
This is the class that actually computes the quantities required to carry out a LS astrometric fit wrt distortion mappings and coordinates of common objects. Namely it computes the Jacobian and gradient of the chi2 (w.r.t. parameters), and the Chi2 itself. It interfaces with the actual modelling of distortions via a mimimum virtual interface AstrometryModel, and the actual mappings via an other virtual interface : Mapping.
In short AstrometryFit aims at computing derivatives of least quares. The terms of the chi2 are of two kinds:
kind 1 -> (T(X_M) - p(F))^T W (T(X_M) - p(F))
with X_M is a measured (2d) position in CCD coordinates, F refers to the position of the object in some space, defined in practise by p. There is one such term per measurement. The default setup would be that p is the projection from sky to some tangent plane and hence T maps the CCD coordinates onto this TP. p is obtained via the DistorsionModel and can be different for all CcdImage's. Depending on what is beeing fitted, one could imagine cases where the projector p is the same for all CcdImages.
Kind 2 -> (p'(F)-p'(R))^T W_R (p'(F)-p'(R)) R refers to some externally-provided reference object position, and p' to some projector from sky to some plane. The reference objects define the overall coordinate frame, which is required when all T and all F are fitted simultaneously. There is one such term per external reference object. There can be more F (fitted) objects than R (reference) objects.
In the same framework, one can fit relative transforms between images by setting p = Identity for all input CcdImages and not fitting T for one of the CcdImage's. One does not need reference object and would then naturally not have any Kind 2 terms.
Definition at line 78 of file AstrometryFit.h.
lsst::jointcal::AstrometryFit::AstrometryFit | ( | std::shared_ptr< Associations > | associations, |
std::shared_ptr< AstrometryModel > | astrometryModel, | ||
double | posError | ||
) |
this is the only constructor
Definition at line 65 of file AstrometryFit.cc.
|
delete |
No copy or move: there is only ever one fitter of a given type.
|
delete |
|
overridevirtual |
Set parameters to fit and assign indices in the big matrix.
[in] | whatToFit | Valid strings: zero or more of "Distortions", "Positions", "PM" which define which parameter set is going to be variable when computing derivatives (leastSquareDerivatives) and minimizing (minimize()). whatToFit="Positions Distortions" will minimize w.r.t mappings and objects positions, and not w.r.t proper motions and refraction modeling. However if proper motions and/or refraction parameters have already been set, then they are accounted for when computing residuals. The string is forwarded to the AstrometryModel, and it can then be used to turn subsets of distortion parameter on or off, if the AstrometryModel implements such a thing. |
Implements lsst::jointcal::FitterBase.
Definition at line 422 of file AstrometryFit.cc.
void lsst::jointcal::AstrometryFit::checkStuff | ( | ) |
DEBUGGING routine.
Definition at line 479 of file AstrometryFit.cc.
|
inherited |
Returns the chi2 for the current state.
Definition at line 42 of file FitterBase.cc.
|
protectedinherited |
Find Measurements and references contributing more than a cut, computed as.
\[ <chi2> + nSigmaCut + rms(chi2). \]
The outliers are NOT removed, and no refit is done.
After returning from here, there are still measurements that contribute above the cut, but their contribution should be evaluated after a refit before discarding them.
[in] | nSigmaCut | Number of sigma to select on. |
[out] | msOutliers | list of MeasuredStar outliers to populate |
[out] | fsOutliers | list of FittedStar outliers to populate |
[out] | cut | value of chi2 that defines which objects are outliers |
Definition at line 52 of file FitterBase.cc.
|
inline |
The transformations used to propagate errors are freezed to the current state.
The routine can be called when the mappings are roughly in place. After the call, the transformations used to propage errors are no longer affected when updating the mappings. This allows to have an exactly linear fit, which can be useful.
Definition at line 117 of file AstrometryFit.h.
|
inline |
Return the model being fit.
Definition at line 122 of file AstrometryFit.h.
|
inherited |
Evaluates the chI^2 derivatives (Jacobian and gradient) for the current whatToFit setting.
The Jacobian is given as triplets in a sparse matrix, the gradient as a dense vector. The parameters which vary, and their indices, are to be set using assignIndices.
tripletList | tripletList of (row,col,value) representing the Jacobian of the chi2. |
grad | The gradient of the chi2. |
Definition at line 344 of file FitterBase.cc.
|
inherited |
Does a 1 step minimization, assuming a linear model.
This is a complete Newton Raphson step. Compute first and second derivatives, solve for the step and apply it, with an optional line search.
It calls assignIndices, leastSquareDerivatives, solves the linear system and calls offsetParams, then removes outliers in a loop if requested. Relies on sparse linear algebra via Eigen's CholmodSupport package.
[in] | whatToFit | See child method assignIndices for valid string values. |
[in] | nSigmaCut | How many sigma to reject outliers at. Outlier rejection ignored for nSigmaCut=0. |
[in] | sigmaRelativeTolerance | Percentage change in the chi2 cut for outliers tolerated for termination. If value is zero, minimization iterations will continue until there are no outliers. |
[in] | doRankUpdate | Use CholmodSimplicialLDLT2.update() to do a fast rank update after outlier removal; otherwise do a slower full recomputation of the matrix. Only matters if nSigmaCut != 0. |
[in] | doLineSearch | Use boost's brent_find_minima to perform a line search after the gradient solution is found, and apply the scale factor to the computed offsets. The line search is done in the domain [-1, 2], but if the scale factor is far from 1.0, then the problem is likely in a significantly non-linear regime. |
[in] | dumpMatrixFile | Write the pre-fit Hessian matrix and gradient to the files with "-mat.txt" and "-grad.txt". Be aware, this requires a large increase in memory usage to create a dense matrix before writing it; the output file may be large. Writing the matrix can be helpful for debugging bad fits. Read it and compute the real eigenvalues (recall that the Hessian is symmetric by construction) with numpy: hessian = np.matrix(np.loadtxt("dumpMatrixFile-mat.txt"))
values, vectors = np.linalg.eigh(hessian)
|
Definition at line 178 of file FitterBase.cc.
|
overridevirtual |
Offset the parameters by the requested quantities.
The used parameter layout is the one from the last call to assignIndices or minimize(). There is no easy way to check that the current setting of whatToFit and the provided Delta vector are compatible: we can only test the size.
[in] | delta | vector of offsets to apply |
Implements lsst::jointcal::FitterBase.
Definition at line 453 of file AstrometryFit.cc.
|
delete |
|
delete |
|
protectedinherited |
Contributions to derivatives from (presumably) outlier terms.
No discarding done.
Definition at line 319 of file FitterBase.cc.
|
protectedinherited |
Remove measuredStar outliers from the fit. No Refit done.
Definition at line 330 of file FitterBase.cc.
|
protectedinherited |
Remove refStar outliers from the fit. No Refit done.
Definition at line 338 of file FitterBase.cc.
|
virtualinherited |
Save the full chi2 term per star that was used in the minimization, for debugging.
Saves results to text files "baseName-meas.csv" and "baseName-ref.csv" for the MeasuredStar and RefStar contributions, respectively. This method is mostly useful for debugging: we will probably want to create a better persistence system for jointcal's internal representations in the future (see DM-12446).
Definition at line 352 of file FitterBase.cc.
|
overrideprotectedvirtual |
Save a CSV file containing residuals of measurement terms.
Implements lsst::jointcal::FitterBase.
Definition at line 495 of file AstrometryFit.cc.
|
overrideprotectedvirtual |
Save a CSV file containing residuals of reference terms.
Implements lsst::jointcal::FitterBase.
Definition at line 568 of file AstrometryFit.cc.
|
protectedinherited |
Definition at line 163 of file FitterBase.h.
|
protectedinherited |
Definition at line 166 of file FitterBase.h.
|
protectedinherited |
Definition at line 172 of file FitterBase.h.
|
protectedinherited |
Definition at line 168 of file FitterBase.h.
|
protectedinherited |
Definition at line 169 of file FitterBase.h.
|
protectedinherited |
Definition at line 167 of file FitterBase.h.
|
protectedinherited |
Definition at line 164 of file FitterBase.h.