Class ConstrainedPhotometryModel

Nested Relationships

Inheritance Relationships

Base Type

Derived Types

Class Documentation

class ConstrainedPhotometryModel : public lsst::jointcal::PhotometryModel

Photometry model with constraints, \(M(x,y) = M_CCD(x,y)*M_visit(u,v)\)

This model consists of the following components:

  • A spatially invariant zero point per CCD, constrained across all visits, \(M_CCD\).

  • A Chebyshev polynomial ( \(a_ij*T_i(x)*T_j(y)\) ) per visit, constrained across all CCDs, \(M_visit\).

Because this model’s parameters are degenerate under multiplication by a constant, \(M=(a*M_CCD)*(1/a*M_visit)\), we hold one CCD’s zero point fixed to remove that degeneracy.

Subclassed by lsst::jointcal::ConstrainedFluxModel, lsst::jointcal::ConstrainedMagnitudeModel

Public Functions

ConstrainedPhotometryModel(CcdImageList const &ccdImageList, geom::Box2D const &focalPlaneBBox, LOG_LOGGER log, int visitOrder = 7, double errorPedestal_ = 0)

Construct a constrained photometry model.

Parameters

  • ccdImageList: The list of CCDImages to construct the model for.

  • focalPlaneBBox: The bounding box of the camera’s focal plane, defining the domain of the visit polynomial.

  • [in] log: An lsst::log::Log instance to log messages to.

  • [in] visitOrder: The order of the visit polynomial.

  • [in] errorPedestal_: A pedestal in flux or magnitude to apply to all MeasuredStar flux errors.

ConstrainedPhotometryModel(ConstrainedPhotometryModel const&)

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

ConstrainedPhotometryModel(ConstrainedPhotometryModel&&)
ConstrainedPhotometryModel &operator=(ConstrainedPhotometryModel const&)
ConstrainedPhotometryModel &operator=(ConstrainedPhotometryModel&&)
Eigen::Index assignIndices(std::string const &whatToFit, Eigen::Index firstIndex)

Assign indices in the full matrix to the parameters being fit in the mappings, starting at firstIndex.

Return

The highest assigned index.

Parameters

  • [in] whatToFit: String containing parameters to fit.

  • [in] firstIndex: Index to start assigning at.

void offsetParams(Eigen::VectorXd const &delta)

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

void freezeErrorTransform()

Once this routine has been called, the error transform is not modified by offsetParams().

The routine can be called when the mappings are roughly in place. After the call, the transformations used to propagate errors are no longer affected when updating the mappings. This allows an exactly linear fit, which can be necessary for some model+data combinations.

void getMappingIndices(CcdImage const &ccdImage, IndexVector &indices) const

Get how this set of parameters (of length Npar()) map into the “grand” fit.

Parameters

  • [in] ccdImage: The ccdImage to look up.

  • [out] indices: The indices of the mapping associated with ccdImage.

std::size_t getTotalParameters() const

Return the total number of parameters in this model.

void computeParameterDerivatives(MeasuredStar const &measuredStar, CcdImage const &ccdImage, Eigen::VectorXd &derivatives) const

Compute the parametric derivatives of this model.

Parameters

  • [in] measuredStar: The measured star with the position and flux to compute at.

  • [in] ccdImage: The ccdImage containing the measured star, to find the correct mapping.

  • [out] derivatives: The computed derivatives. Must be pre-allocated to the correct size.

void dump(std::ostream &stream = std::cout) const

Dump the contents of the transforms, for debugging.

Protected Types

typedef std::unordered_map<CcdImageKey, std::unique_ptr<ChipVisitPhotometryMapping>> MapType
typedef std::map<VisitIdType, std::shared_ptr<PhotometryMapping>> VisitMapType
typedef std::map<CcdIdType, std::shared_ptr<PhotometryMapping>> ChipMapType

Protected Functions

PhotometryMappingBase *findMapping(CcdImage const &ccdImage) const

Return a pointer to the mapping associated with this ccdImage.

template<class ChipTransform, class VisitTransform, class ChipVisitMapping>
void initialize(CcdImageList const &ccdImageList, geom::Box2D const &focalPlaneBBox, int visitOrder)

Initialize the chip, visit, and chipVisit mappings by creating appropriate transforms and mappings.

virtual double initialChipCalibration(std::shared_ptr<afw::image::PhotoCalib const> photoCalib) = 0

Return the initial calibration to use from this photoCalib.

PrepPhotoCalib prepPhotoCalib(CcdImage const &ccdImage) const

Helper for preparing toPhotoCalib()

Protected Attributes

MapType _chipVisitMap
VisitMapType _visitMap
ChipMapType _chipMap
struct PrepPhotoCalib

To hold the return of prepPhotoCalib.

Public Members

double chipConstant
afw::geom::TransformPoint2ToGeneric visitTransform
std::shared_ptr<afw::geom::TransformPoint2ToPoint2> pixToFocal
double visitMean