lsst::meas::algorithms::SizeMagnitudeStarSelector Class Reference

#include <SizeMagnitudeStarSelector.h>

Public Types
typedef float	PixelT
typedef lsst::afw::image::Exposure < PixelT >	Exposure
typedef lsst::afw::geom::PointD	PointD
typedef lsst::pex::policy::Policy	Policy
typedef lsst::afw::table::SourceRecord	SourceRecord
typedef lsst::afw::table::SourceTable	SourceTable
typedef lsst::afw::table::SourceCatalog	SourceCatalog
typedef lsst::meas::algorithms::PsfCandidate < PixelT >	PsfCandidateT
typedef PsfCandidateT::PtrList	PsfCandidateList

Public Member Functions
	SizeMagnitudeStarSelector (const Policy &policy)
	Create a size-magnitude star selector from a policy. More...
	~SizeMagnitudeStarSelector ()
	Destructor. More...
PsfCandidateList	selectStars (const Exposure &exposure, const SourceCatalog &sourceList, boost::shared_ptr< afw::table::ReferenceMatchVector const > matches=boost::shared_ptr< afw::table::ReferenceMatchVector const >()) const
	Find a set of stars from an input list of Sources. More...

Private Member Functions
double	calculateSourceSize (const SourceRecord &source, const Exposure &exposure) const
	Calculates a robust size measurement for a source. More...
	SizeMagnitudeStarSelector (const SizeMagnitudeStarSelector &rhs)
	This class is not intended to be copied. More...
void	operator= (const SizeMagnitudeStarSelector &rhs)

Private Attributes
boost::shared_ptr < SizeMagnitudeStarSelectorImpl >	pImpl

Detailed Description

Definition at line 49 of file SizeMagnitudeStarSelector.h.

Member Typedef Documentation

typedef lsst::afw::image::Exposure<PixelT> lsst::meas::algorithms::SizeMagnitudeStarSelector::Exposure

Definition at line 53 of file SizeMagnitudeStarSelector.h.

typedef float lsst::meas::algorithms::SizeMagnitudeStarSelector::PixelT

Definition at line 52 of file SizeMagnitudeStarSelector.h.

typedef lsst::afw::geom::PointD lsst::meas::algorithms::SizeMagnitudeStarSelector::PointD

Definition at line 54 of file SizeMagnitudeStarSelector.h.

typedef lsst::pex::policy::Policy lsst::meas::algorithms::SizeMagnitudeStarSelector::Policy

Definition at line 55 of file SizeMagnitudeStarSelector.h.

typedef PsfCandidateT::PtrList lsst::meas::algorithms::SizeMagnitudeStarSelector::PsfCandidateList

Definition at line 61 of file SizeMagnitudeStarSelector.h.

typedef lsst::meas::algorithms::PsfCandidate<PixelT> lsst::meas::algorithms::SizeMagnitudeStarSelector::PsfCandidateT

Definition at line 59 of file SizeMagnitudeStarSelector.h.

typedef lsst::afw::table::SourceCatalog lsst::meas::algorithms::SizeMagnitudeStarSelector::SourceCatalog

Definition at line 58 of file SizeMagnitudeStarSelector.h.

typedef lsst::afw::table::SourceRecord lsst::meas::algorithms::SizeMagnitudeStarSelector::SourceRecord

Definition at line 56 of file SizeMagnitudeStarSelector.h.

typedef lsst::afw::table::SourceTable lsst::meas::algorithms::SizeMagnitudeStarSelector::SourceTable

Definition at line 57 of file SizeMagnitudeStarSelector.h.

Constructor & Destructor Documentation

lsst::meas::algorithms::SizeMagnitudeStarSelector::SizeMagnitudeStarSelector

(

const Policy &

policy

)

Create a size-magnitude star selector from a policy.

Parameters

[in]

policy:

see policy/SizeMagnitudeStarSelectorDictionary.paf

Definition at line 58 of file SizeMagnitudeStarSelector.cc.

{
    using shapelet::ConfigFile;

    // Convert Policy info into my ConfigFile format:
    ConfigFile params;
    params["minsize"] = policy.getDouble("minsize");
    params["maxsize"] = policy.getDouble("maxsize");
    params["logsize"] = policy.getBool("logsize");
    params["minmag"] = policy.getDouble("minmag");
    params["maxmag"] = policy.getDouble("maxmag");
    params["starfrac"] = policy.getDouble("starfrac");
    params["startn1"] = policy.getDouble("startn1");
    params["fitorder"] = policy.getInt("fitorder");
    params["fitsigclip"] = policy.getDouble("fitsigclip");
    params["starsperbin"] = policy.getInt("starsperbin");
    params["purityratio"] = policy.getDouble("purityratio");

    // The rest of these are just given defaults.  
    // In my experience, there is not much reason to make these
    // run-time modifiable.
    params["maxoutmag"] = params["maxmag"];
    params["ndivx"] = 1;
    params["ndivy"] = 1;
    params["magstep1"] = 0.25;
    params["magstep2"] = 0.1;
    params["reject1"] = params["fitsigclip"];
    params["reject2"] = params["fitsigclip"];
    params["maxratio1"] = 3.0 * double(params["purityratio"]);
    params["binsize1"] = 0.1;
    params["minbinsize"] = 0.01;
    params["miniter1"] = 3;
    params["miniter2"] = 2;
    params["startn2"] = 3 * int(params["startn1"]);
    params["okvalcount"] = 2;
    params["maxrms"] = 0.05;
    params["maxrefititer"] = 5;

    pImpl = boost::shared_ptr<SizeMagnitudeStarSelectorImpl>(new SizeMagnitudeStarSelectorImpl(params, policy));
}

lsst::meas::algorithms::SizeMagnitudeStarSelector::~SizeMagnitudeStarSelector ( )

inline

Destructor.

Definition at line 73 of file SizeMagnitudeStarSelector.h.

{};

lsst::meas::algorithms::SizeMagnitudeStarSelector::SizeMagnitudeStarSelector ( const SizeMagnitudeStarSelector &  rhs )

private

This class is not intended to be copied.

Member Function Documentation

double lsst::meas::algorithms::SizeMagnitudeStarSelector::calculateSourceSize ( const SourceRecord &  source, const Exposure &  exposure  ) const

private

Calculates a robust size measurement for a source.

This measures the 2nd order shapelet decomposition of the object, allowing the sigma to vary until the b11 term goes to zero. When this happens, the sigma is basically the best-fit Gaussian sigma. Also, this value of sigma gives the best S/N properties for the rest of the shapelet vector.

This size measurement has proven to be a good one to use for the size-magnitude star finder algorithm, since the size is very stable with stellar magnitude.

Note

This may not be necessary. Lupton says that there is already a similar measurement being done in the LSST stack. Should check if the existing values are ok for star finder algorithm. (I'm not sure which entry in Source they would be...) Therefore, this function may be a good candidate for a having its action be specifiable by a Policy parameter.

Definition at line 99 of file SizeMagnitudeStarSelector.cc.

{
    double sigma = sqrt(source.getIxx() + source.getIyy());
    if (!(sigma > 0.)) return -1.;
    Shapelet shape(4, sigma);
    double x = source.getX();
    double y = source.getY();
    PointD pos(x, y);
    if (shape.measureFromImage(
            source, pos, false, false, pImpl->getAperture(), exposure)) {
        return shape.getSigma();
    } else {
        return -1.;
    }
}

void lsst::meas::algorithms::SizeMagnitudeStarSelector::operator= ( const SizeMagnitudeStarSelector &  rhs )

private

SizeMagnitudeStarSelector::PsfCandidateList lsst::meas::algorithms::SizeMagnitudeStarSelector::selectStars	(	const Exposure &	exposure,
		const SourceCatalog &	sourceList,
		boost::shared_ptr< afw::table::ReferenceMatchVector const >	matches = boost::shared_ptr< afw::table::ReferenceMatchVector const>()
	)		const

Find a set of stars from an input list of Sources.

This function uses an algorithm based on looking for a stellar locus in the size-magnitude diagram that has constant size.

It basically construct a histogram of counts with respect to size, starting with just the bright objects and then pushing down in magnitude until the stellar peak starts to bleed into the galaxies, at which point it stops.

Parameters

exposure	the exposure on which the sources are found
sourceList	The input list of sources to consider
matches	astrometric matches (ignored by this algorithm)

Definition at line 133 of file SizeMagnitudeStarSelector.cc.

        {
    pexLogging::Debug traceLog("meas.algorithms.SizeMagnitudeStarSelector"); // trace output goes here
    const unsigned int MIN_OBJ_TO_TRY = 30;

    typedef Exposure::MaskedImageT MaskedImage;
    std::vector<shapelet::PotentialStar*> maybeStars;

    // First get a list of potential stars
    const int nSources = sourceList.size();
    traceLog.debug<4>("%d candidate stars", nSources);
    for (int i=0; i<nSources; ++i) {
        double const x = sourceList[i].getX();
        double const y = sourceList[i].getY();
        double const size = calculateSourceSize(sourceList[i], exposure);
        double const mag = calculateSourceMagnitude(sourceList[i], exposure);

        shapelet::Position pos(x, y);

        // Range checking
        bool ok = true;
        if (!pImpl->isOkSize(size)) {
            ok = false;
        }
        if (ok && !pImpl->isOkMag(mag)) {
            ok = false;
        }
        traceLog.debug<5>("i, x, y, size, mag = %d %.1f, %.1f %g %g: %d", i, x, y, size, mag, ok);

        if (ok) {
            double logSize = pImpl->convertToLogSize(size);
            maybeStars.push_back(new shapelet::PotentialStar(pos, mag, logSize, i, ""));
        }
    }
    traceLog.debug<4>("Total potential stars = %d", maybeStars.size());
    if (maybeStars.size() < MIN_OBJ_TO_TRY) {
        // Too few objects for algorithm to have any chance of producing reasonable output.
         pex::logging::Log::getDefaultLog().log(pexLogging::Log::WARN,
                  str(boost::format("Only %d viable objects for star selection. "
                                    "This algorithm needs at least %d objects to try to find stars")
                      % maybeStars.size() % MIN_OBJ_TO_TRY));
                                                                
        return PsfCandidateList();
    }

    // Run the actual algorithm
    std::vector<shapelet::PotentialStar*> stars = pImpl->findStars(maybeStars);
    traceLog.debug<4>("Identified %d stars", stars.size());

    // Convert the results into a PsfCandidateList
    //MaskedImage::ConstPtr imagePtr = MaskedImage::ConstPtr(new MaskedImage(exposure.getMaskedImage(), false));
    CONST_PTR(Exposure) expPtr = CONST_PTR(Exposure)(new Exposure(exposure, false));
    PsfCandidateList psfCandidateList;
    const int nStars = stars.size();
    for (int k=0; k<nStars; ++k) {
        if (pImpl->isOkOutputMag(stars[k]->getMag())) {
            int i=stars[k]->getIndex();
            PTR(PsfCandidateT) psfCandidate(new PsfCandidateT(
                sourceList.get(i),
                expPtr,
                stars[k]->getPos().getX(),
                stars[k]->getPos().getY()));
            psfCandidateList.push_back(psfCandidate);
        }
    }

    return psfCandidateList;
}

Member Data Documentation

boost::shared_ptr<SizeMagnitudeStarSelectorImpl> lsst::meas::algorithms::SizeMagnitudeStarSelector::pImpl

private

Definition at line 126 of file SizeMagnitudeStarSelector.h.

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

• /home/lsstsw/stack/Linux64/meas_algorithms/11.0-2-gb8b8ce7/include/lsst/meas/algorithms/SizeMagnitudeStarSelector.h
• /home/lsstsw/stack/Linux64/meas_algorithms/11.0-2-gb8b8ce7/src/SizeMagnitudeStarSelector.cc