lsst::jointcal::SimpleAstrometryModel Class Reference

A model where there is one independent transform per CcdImage. More...

#include <SimpleAstrometryModel.h>

Inheritance diagram for lsst::jointcal::SimpleAstrometryModel:

Public Member Functions
	SimpleAstrometryModel (CcdImageList const &ccdImageList, std::shared_ptr< ProjectionHandler const > projectionHandler, bool initFromWCS, unsigned nNotFit=0, unsigned order=3)
	SimpleAstrometryModel (SimpleAstrometryModel const &)=delete
	No copy or move: there is only ever one instance of a given model (i.e.. per ccd+visit)
	SimpleAstrometryModel (SimpleAstrometryModel &&)=delete
SimpleAstrometryModel &	operator= (SimpleAstrometryModel const &)=delete
SimpleAstrometryModel &	operator= (SimpleAstrometryModel &&)=delete
const AstrometryMapping *	getMapping (CcdImage const &) const override
	Mapping associated to a given CcdImage.
Eigen::Index	assignIndices (std::string const &whatToFit, Eigen::Index firstIndex) override
	Positions the various parameter sets into the parameter vector, starting at firstIndex.
void	offsetParams (Eigen::VectorXd const &delta) override
	Offset the parameters by the provided amounts (by -delta).
const std::shared_ptr< AstrometryTransform const >	getSkyToTangentPlane (CcdImage const &ccdImage) const override
	the mapping of sky coordinates (i.e.
void	freezeErrorTransform () override
std::size_t	getTotalParameters () const override
	Return the total number of parameters in this model.
void	print (std::ostream &out) const override
	Print a string representation of the contents of this mapping, for debugging.
AstrometryTransform const &	getTransform (CcdImage const &ccdImage) const
	Access to mappings.
std::shared_ptr< afw::geom::SkyWcs >	makeSkyWcs (CcdImage const &ccdImage) const override
	Make a SkyWcs that contains this model.
	~SimpleAstrometryModel ()=default
std::size_t	getNpar (CcdImage const &ccdImage) const
	Return the number of parameters in the mapping of CcdImage.
bool	validate (CcdImageList const &ccdImageList, int ndof) const
	Return true if this is a "reasonable" model.

Protected Attributes
LOG_LOGGER	_log
	lsst.logging instance, to be created by a subclass so that messages have consistent name.

Private Member Functions
AstrometryMapping *	findMapping (CcdImage const &ccdImage) const override
	Return a pointer to the mapping associated with this ccdImage.

Detailed Description

A model where there is one independent transform per CcdImage.

This modeling of distortions can even accommodate images set mixing instruments

Parameters

ccdImageList	The exposures that will be fit.
projectionHandler	The projection from "Sky" (where the "true" coordinates live) to "Tangent Plane" (where the fitting occurs).
initFromWCS	Initialize the model parameters from the original exposure Wcs parameters?
nNotFit	How many exposure to hold fixed and not be fit? (the first n will be selected) .
order	The polynomial order of each exposure's pixel-tangent plane mapping.

Definition at line 62 of file SimpleAstrometryModel.h.

Constructor & Destructor Documentation

SimpleAstrometryModel() [1/3]

lsst::jointcal::SimpleAstrometryModel::SimpleAstrometryModel	(	CcdImageList const &	ccdImageList,
		std::shared_ptr< ProjectionHandler const >	projectionHandler,
		bool	initFromWCS,
		unsigned	nNotFit = 0,
		unsigned	order = 3 )

Definition at line 42 of file SimpleAstrometryModel.cc.

        : AstrometryModel(LOG_GET("lsst.jointcal.SimpleAstrometryModel")),
          _skyToTangentPlane(std::move(projectionHandler))
 
{
    std::size_t count = 0;
 
    for (auto i = ccdImageList.cbegin(); i != ccdImageList.cend(); ++i, ++count) {
        const CcdImage &im = **i;
        if (count < nNotFit) {
            std::unique_ptr<SimpleAstrometryMapping> id(
                    new SimpleAstrometryMapping(AstrometryTransformIdentity()));
            id->setIndex(-1);  // non sense, because it has no parameters
            _myMap[im.getHashKey()] = std::move(id);
        } else
        // Given how AssignIndices works, only the SimplePolyMappings
        // will actually be fitted, as nNotFit requests.
        {
            // first check that there are enough measurements for the requested polynomial order.
            size_t nObj = im.getCatalogForFit().size();
            if (nObj == 0) {
                LOGLS_WARN(_log, "Empty catalog from image: " << im.getName());
                continue;
            }
            AstrometryTransformPolynomial pol(order);
            if (pol.getOrder() > 0)  // if not, it cannot be decreased
            {
                while (pol.getNpar() > 2 * nObj) {
                    LOGLS_WARN(_log, "Reducing polynomial order from "
                                             << pol.getOrder() << ", due to too few sources (" << nObj
                                             << " vs. " << pol.getNpar() << " parameters)");
                    pol.setOrder(pol.getOrder() - 1);
                }
            }
            /* We have to center and normalize the coordinates so that
               the fit matrix is not too ill-conditionned. Basically, x
               and y in pixels are mapped to [-1,1]. When the
               transformation of SimplePolyMapping transformation is
               accessed, the combination of the normalization and the
               fitted transformation is returned, so that the trick
               remains hidden
             */
            const Frame &frame = im.getImageFrame();
            AstrometryTransformLinear shiftAndNormalize = normalizeCoordinatesTransform(frame);
            if (initFromWcs) {
                pol = AstrometryTransformPolynomial(im.getPixelToTangentPlane().get(), frame, order);
                pol = pol * shiftAndNormalize.inverted();
            }
            _myMap[im.getHashKey()] =
                    std::unique_ptr<SimpleAstrometryMapping>(new SimplePolyMapping(shiftAndNormalize, pol));
        }
    }
}

SimpleAstrometryModel() [2/3]

lsst::jointcal::SimpleAstrometryModel::SimpleAstrometryModel ( SimpleAstrometryModel const & )

delete

No copy or move: there is only ever one instance of a given model (i.e.. per ccd+visit)

SimpleAstrometryModel() [3/3]

lsst::jointcal::SimpleAstrometryModel::SimpleAstrometryModel ( SimpleAstrometryModel && )

delete

~SimpleAstrometryModel()

lsst::jointcal::SimpleAstrometryModel::~SimpleAstrometryModel ( )

default

Member Function Documentation

assignIndices()

Eigen::Index lsst::jointcal::SimpleAstrometryModel::assignIndices ( std::string const & whatToFit, Eigen::Index firstIndex )

overridevirtual

Positions the various parameter sets into the parameter vector, starting at firstIndex.

Implements lsst::jointcal::AstrometryModel.

Definition at line 102 of file SimpleAstrometryModel.cc.

                                                                                                 {
    if (whatToFit.find("Distortions") == std::string::npos) {
        LOGLS_ERROR(_log, "AssignIndices was called and Distortions is *not* in whatToFit.");
        return 0;
    }
    Eigen::Index index = firstIndex;
    for (auto & i : _myMap) {
        auto *p = dynamic_cast<SimplePolyMapping *>(&*(i.second));
        if (!p) continue;  // it should be AstrometryTransformIdentity
        p->setIndex(index);
        index += p->getNpar();
    }
    return index;
}

findMapping()

AstrometryMapping * lsst::jointcal::SimpleAstrometryModel::findMapping ( CcdImage const & ccdImage ) const

overrideprivatevirtual

Return a pointer to the mapping associated with this ccdImage.

Implements lsst::jointcal::AstrometryModel.

Definition at line 171 of file SimpleAstrometryModel.cc.

                                                                                    {
    auto i = _myMap.find(ccdImage.getHashKey());
    if (i == _myMap.end())
        throw LSST_EXCEPT(pex::exceptions::InvalidParameterError,
                          "SimpleAstrometryModel cannot find CcdImage " + ccdImage.getName());
    return i->second.get();
}

freezeErrorTransform()

void lsst::jointcal::SimpleAstrometryModel::freezeErrorTransform ( )

overridevirtual

Implements lsst::jointcal::AstrometryModel.

Definition at line 124 of file SimpleAstrometryModel.cc.

                                                 {
    for (auto &i : _myMap) i.second->freezeErrorTransform();
}

getMapping()

const AstrometryMapping * lsst::jointcal::SimpleAstrometryModel::getMapping ( CcdImage const & ) const

overridevirtual

Mapping associated to a given CcdImage.

Implements lsst::jointcal::AstrometryModel.

Definition at line 98 of file SimpleAstrometryModel.cc.

                                                                                         {
    return findMapping(ccdImage);
}

getNpar()

std::size_t lsst::jointcal::AstrometryModel::getNpar ( CcdImage const & ccdImage ) const

inlineinherited

Return the number of parameters in the mapping of CcdImage.

Definition at line 56 of file AstrometryModel.h.

{ return findMapping(ccdImage)->getNpar(); }

getSkyToTangentPlane()

const std::shared_ptr< AstrometryTransform const > lsst::jointcal::SimpleAstrometryModel::getSkyToTangentPlane ( CcdImage const & ccdImage ) const

inlineoverridevirtual

the mapping of sky coordinates (i.e.

the coordinate system in which fitted stars are reported) onto the Tangent plane (into which the pixel coordinates are transformed)

Implements lsst::jointcal::AstrometryModel.

Definition at line 87 of file SimpleAstrometryModel.h.

                                                     {
        return _skyToTangentPlane->getSkyToTangentPlane(ccdImage);
    }

getTotalParameters()

std::size_t lsst::jointcal::SimpleAstrometryModel::getTotalParameters ( ) const

overridevirtual

Return the total number of parameters in this model.

Implements lsst::jointcal::AstrometryModel.

Definition at line 128 of file SimpleAstrometryModel.cc.

                                                          {
    std::size_t total = 0;
    for (auto &i : _myMap) {
        total += i.second->getNpar();
    }
    return total;
}

getTransform()

const AstrometryTransform & lsst::jointcal::SimpleAstrometryModel::getTransform

(

CcdImage const &

ccdImage

)

const

Access to mappings.

Definition at line 147 of file SimpleAstrometryModel.cc.

                                                                                             {
    return dynamic_cast<const SimplePolyMapping *>(findMapping(ccdImage))->getTransform();
}

makeSkyWcs()

std::shared_ptr< afw::geom::SkyWcs > lsst::jointcal::SimpleAstrometryModel::makeSkyWcs ( CcdImage const & ccdImage ) const

overridevirtual

Make a SkyWcs that contains this model.

Parameters

ccdImage

The exposure to create the SkyWcs for.

Returns

SkyWcs containing this model.

Implements lsst::jointcal::AstrometryModel.

Definition at line 151 of file SimpleAstrometryModel.cc.

                                                                                             {
    auto proj = std::dynamic_pointer_cast<const TanRaDecToPixel>(getSkyToTangentPlane(ccdImage));
    jointcal::Point tangentPoint(proj->getTangentPoint());
 
    auto polyMap = getTransform(ccdImage).toAstMap(ccdImage.getImageFrame());
    ast::Frame pixelFrame(2, "Domain=PIXELS");
    ast::Frame iwcFrame(2, "Domain=IWC");
 
    // make a basic SkyWcs and extract the IWC portion
    auto iwcToSkyWcs = afw::geom::makeSkyWcs(
            geom::Point2D(0, 0), geom::SpherePoint(tangentPoint.x, tangentPoint.y, geom::degrees),
            afw::geom::makeCdMatrix(1.0 * geom::degrees, 0 * geom::degrees, true));
    auto iwcToSkyMap = iwcToSkyWcs->getFrameDict()->getMapping("PIXELS", "SKY");
    auto skyFrame = iwcToSkyWcs->getFrameDict()->getFrame("SKY");
 
    ast::FrameDict frameDict(pixelFrame, *polyMap, iwcFrame);
    frameDict.addFrame("IWC", *iwcToSkyMap, *skyFrame);
    return std::make_shared<afw::geom::SkyWcs>(frameDict);
}

offsetParams()

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

overridevirtual

Offset the parameters by the provided amounts (by -delta).

The shifts are applied according to the indices given in assignIndices.

Parameters

[in]

delta

vector of offsets to apply

Implements lsst::jointcal::AstrometryModel.

Definition at line 117 of file SimpleAstrometryModel.cc.

                                                                   {
    for (auto &i : _myMap) {
        auto mapping = i.second.get();
        mapping->offsetParams(delta.segment(mapping->getIndex(), mapping->getNpar()));
    }
}

operator=() [1/2]

SimpleAstrometryModel & lsst::jointcal::SimpleAstrometryModel::operator= ( SimpleAstrometryModel && )

delete

operator=() [2/2]

SimpleAstrometryModel & lsst::jointcal::SimpleAstrometryModel::operator= ( SimpleAstrometryModel const & )

delete

print()

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

overridevirtual

Print a string representation of the contents of this mapping, for debugging.

This string representation can be very verbose, as it contains all of the parameters of all of the transforms in this model.

Implements lsst::jointcal::AstrometryModel.

Definition at line 136 of file SimpleAstrometryModel.cc.

                                                       {
    out << "SimpleAstrometryModel: " << _myMap.size() << " mappings" << std::endl;
    out << *_skyToTangentPlane << std::endl;
    out << "Sensor to sky transforms:" << std::endl;
    for (auto &i : _myMap) {
        out << i.first << std::endl;
        out << *(i.second) << std::endl;
        out << std::endl;
    }
}

validate()

bool lsst::jointcal::AstrometryModel::validate ( CcdImageList const & ccdImageList, int ndof ) const

inherited

Return true if this is a "reasonable" model.

Parameters

ccdImageList	The ccdImages to test the model validity on.
ndof	The number of degrees of freedom in the fit, e.g. from Fitterbase.computeChi2().

Returns

True if the model is valid on all ccdImages.

Definition at line 30 of file AstrometryModel.cc.

                                                                               {
    bool check = true;
    if (ndof < 0) {
        check &= false;
        LOGLS_ERROR(_log, "This model only has "
                                  << ndof << " degrees of freedom, with " << getTotalParameters()
                                  << " total parameters. Reduce the model complexity (e.g. polynomial order)"
                                     " to better match the number of measured sources.");
    }
    return check;
}

Member Data Documentation

_log

LOG_LOGGER lsst::jointcal::AstrometryModel::_log

protectedinherited

lsst.logging instance, to be created by a subclass so that messages have consistent name.

Definition at line 117 of file AstrometryModel.h.

---

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

• /j/snowflake/release/lsstsw/stack/lsst-scipipe-9.0.0/Linux64/jointcal/g82479be7b0+e2bd23ab8b/include/lsst/jointcal/SimpleAstrometryModel.h
• /j/snowflake/release/lsstsw/stack/lsst-scipipe-9.0.0/Linux64/jointcal/g82479be7b0+e2bd23ab8b/src/SimpleAstrometryModel.cc