File simpleShape.h¶
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namespace
lsst Class for a simple mapping implementing a generic AstrometryTransform.
Remove all non-astronomical counts from the Chunk Exposure’s pixels.
Forward declarations for lsst::utils::Cache
For details on the Cache class, see the Cache.h file.
It uses a template rather than a pointer so that the derived classes can use the specifics of the transform. The class simplePolyMapping overloads a few routines.
A base class for image defects
Numeric constants used by the Integrate.h integrator routines.
Compute Image Statistics
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Gauss-Kronrod-Patterson quadrature coefficients for use in quadpack routine qng. These coefficients were calculated with 101 decimal digit arithmetic by L. W. Fullerton, Bell Labs, Nov 1981.
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The Statistics class itself can only handle lsst::afw::image::MaskedImage() types. The philosophy has been to handle other types by making them look like lsst::afw::image::MaskedImage() and reusing that code. Users should have no need to instantiate a Statistics object directly, but should use the overloaded makeStatistics() factory functions.
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namespace
meas -
namespace
extensions -
namespace
simpleShape¶ -
class
SimpleShape: public lsst::meas::base::SimpleAlgorithm Public Types
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typedef SimpleShapeControl
Control
Public Functions
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virtual void
measure(afw::table::SourceRecord &measRecord, afw::image::Exposure<float> const &exposure) const Called to measure a single child source in an image.
Before this method is called, all neighbors will be replaced with noise, using the outputs of the deblender. Outputs should be saved in the given SourceRecord, which can also be used to obtain centroid (see SafeCentroidExtractor) and shape (see SafeShapeExtractor) information.
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virtual void
fail(afw::table::SourceRecord &measRecord, lsst::meas::base::MeasurementError *error = NULL) const Handle an exception thrown by the current algorithm by setting flags in the given record.
fail() is called by the measurement framework when an exception is allowed to propagate out of one the algorithm’s measure() methods. It should generally set both a general failure flag for the algorithm as well as a specific flag indicating the error condition, if possible. To aid in this, if the exception was an instance of MeasurementError, it will be passed in, carrying information about what flag to set.
An algorithm can also to chose to set flags within its own measure() methods, and then just return, rather than throw an exception. However, fail() should be implemented even when all known failure modes do not throw exceptions, to ensure that unexpected exceptions thrown in lower-level code are properly handled.
Public Static Functions
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static base::FlagDefinitionList const &
getFlagDefinitions()
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template<typename
T>
static SimpleShapeResultcomputeMoments(afw::geom::ellipses::Ellipse const &weight, afw::image::MaskedImage<T> const &image, double nSigmaRegion = 3.0) Compute the Gaussian-weighted moments of an image.
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[in] weight: An ellipse object of Gaussian weights to apply to the measurement.[in] image: A Masked image instance with int float or double pixels.[in] nSigmaRegion: Maximum radius for pixels to include, in units of sigma
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static Eigen::Matrix<double, 5, 6>
convertRawMoments(Eigen::Matrix<double, 6, 1> const &q, afw::geom::ellipses::Quadrupole &quadrupole, geom::Point2D ¢er) Convert linear raw moments into an ellipse and centroid, and return the derivative of the conversion.
For weight function
\(w\) and data \(p\), the “raw” moments \(Q\) are defined as:\[\begin{split}\begin{eqnarray*} Q_0 &=& \sum_n w(x_n, y_n) p_n \\ Q_{xx} &=& \sum_n w(x_n, y_n) x_n^2 p_n \\ Q_{yy} &=& \sum_n w(x_n, y_n) y_n^2 p_n \\ Q_{xy} &=& \sum_n w(x_n, y_n) x_n y_n p_n \\ Q_x &=& \sum_n w(x_n, y_n) x_n p_n \\ Q_y &=& \sum_n w(x_n, y_n) y_n p_n \end{eqnarray*}\end{split}\]whereas the converted ellipse and centroid moments are:\[\begin{split}\begin{eqnarray*} M_{xx} &=& Q_{xx} / Q_0 - Q_x^2 \\ M_{xx} &=& Q_{yy} / Q_0 - Q_y^2 \\ M_{xx} &=& Q_{xy} / Q_0 - Q_x Q_y \\ M_x &=& Q_x / Q_0 \\ M_y &=& Q_y / Q_0 \end{eqnarray*}\end{split}\]- Note
This function is mainly intended for internal use, and is only exposed publically so it can be unit-tested in Python.
Note the slightly unusual ordering; this is for consistency with afw::geom::ellipses::Ellipse.
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static Eigen::Matrix<double, 5, 5>
correctWeightedMoments(afw::geom::ellipses::Quadrupole const &weight, afw::geom::ellipses::Quadrupole &ellipse, geom::Point2D ¢er) Correct moments measured with a Gaussian weight function by assuming the data was also an elliptical Gaussian, and return the derivative of the correction.
If we naively measure Gaussian-weighted moments, we’ll measure the moments of the product of the weight function and the data. What we want is the moments of the data, as if we had measured them with no weight function (but without sacrificing the S/N benefit that comes from using a weight function). To do that, we assume the data is also an elliptical Gaussian, and “divide” the weight function from the measured moments to compute it.
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This function is mainly intended for internal use, and is only exposed publically so it can be unit-tested in Python.
If \(W\) and \(M\) are the quadruple matrices of the weight function and measurement, and \(\eta\) is the measured centroid (we work in a coordinate system where the weight function is centered at the origin), then the corrected quadrupole matrix \(C\) and centroid are \(\nu\) are:
\[\begin{split}\begin{eqnarray*} C &=& \left(M^{-1} - W^{-1}\right)^{-1} \\ \nu &=& C M^{-1} \eta \end{eqnarray*}\end{split}\]
Private Members
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SimpleShapeResultKey
_resultKey¶
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lsst::meas::base::SafeCentroidExtractor
_centroidExtractor¶
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typedef SimpleShapeControl
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class
SimpleShapeControl - #include <simpleShape.h>
A C++ control class to handle SdssShapeAlgorithm’s configuration.
Public Functions
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lsst::meas::extensions::simpleShape::SimpleShapeControl::LSST_CONTROL_FIELD(sigma, double, "Sigma of circular Gaussian used as weight function, in pixels")
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lsst::meas::extensions::simpleShape::SimpleShapeControl::LSST_CONTROL_FIELD(nSigmaRegion, double, "Maximum radius for pixels to include, in units of sigma")
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SimpleShapeControl()
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class
SimpleShapeResult - #include <simpleShape.h>
Struct to hold the results of SimpleShape when we don’t run it as a plugin.
Public Functions
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bool
getFlag(int index) const
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SimpleShapeResult() Constructor; initializes everything to Nan.
Public Members
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afw::geom::ellipses::Quadrupole
ellipse Measured second moments.
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geom::Point2D
center Measured first moments, or the input center if !recentroid.
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Eigen::Matrix<double, 5, 5>
covariance Matrix of uncertainties; ordered Ixx, Iyy, Ixy, Ix, Iy.
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std::bitset<SimpleShape::N_FLAGS>
flags
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bool
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class
SimpleShapeResultKey: public lsst::afw::table::FunctorKey<SimpleShapeResult> Unnamed Group
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bool
operator==(SimpleShapeResultKey const &other) const Compare the FunctorKey for equality with another, using the underlying Keys.
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bool
operator!=(SimpleShapeResultKey const &other) const
Public Functions
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SimpleShapeResultKey()
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SimpleShapeResultKey(lsst::afw::table::SubSchema const &s) Construct from a subschema, assuming _xx, _yy, etc. subfields.
If a schema has “a_xx”, “a_yy”, etc. fields, this constructor allows you to construct a SimpleShapeResultKey via:
SimpleShapeResultKey k(schema["a"]);
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virtual SimpleShapeResult
get(afw::table::BaseRecord const &record) const
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virtual void
set(afw::table::BaseRecord &record, SimpleShapeResult const &value) const
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bool
isValid() const Return True if the key is valid.
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lsst::meas::base::FlagHandler const &
getFlagHandler() const
Public Static Functions
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static SimpleShapeResultKey
addFields(afw::table::Schema &schema, std::string const &name)
Private Members
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lsst::afw::table::QuadrupoleKey
_shapeResult¶
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lsst::afw::table::Point2DKey
_centroidResult¶
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lsst::afw::table::CovarianceMatrixKey<double, 5>
_uncertantyResult¶
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lsst::meas::base::FlagHandler
_flagHandler¶
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bool
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class
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namespace
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namespace