lsst::afw::math::Kernel Class Reference

Kernels are used for convolution with MaskedImages and (eventually) Images. More...

#include <Kernel.h>

Inheritance diagram for lsst::afw::math::Kernel:

Classes
struct	PersistenceHelper

Public Types
using	Pixel = double
using	SpatialFunctionPtr = std::shared_ptr< lsst::afw::math::Function2< double > >
using	SpatialFunction = lsst::afw::math::Function2< double >
using	NullSpatialFunction = lsst::afw::math::NullFunction2< double >
using	kernel_fill_factor = generic_kernel_tag

Public Member Functions
	Kernel ()
	Construct a null Kernel of size 0,0. More...
	Kernel (int width, int height, unsigned int nKernelParams, SpatialFunction const &spatialFunction=NullSpatialFunction())
	Construct a spatially invariant Kernel or a spatially varying Kernel with one spatial function that is duplicated as needed. More...
	Kernel (int width, int height, const std::vector< SpatialFunctionPtr > spatialFunctionList)
	Construct a spatially varying Kernel with a list of spatial functions (one per kernel parameter) More...
	Kernel (const Kernel &)=delete
	Kernel (Kernel &&)=delete
Kernel &	operator= (const Kernel &)=delete
Kernel &	operator= (Kernel &&)=delete
	~Kernel () override=default
virtual std::shared_ptr< Kernel >	clone () const =0
	Return a pointer to a deep copy of this kernel. More...
virtual std::shared_ptr< Kernel >	resized (int width, int height) const =0
	Return a pointer to a clone with specified kernel dimensions. More...
double	computeImage (lsst::afw::image::Image< Pixel > &image, bool doNormalize, double x=0.0, double y=0.0) const
	Compute an image (pixellized representation of the kernel) in place. More...
lsst::geom::Extent2I const	getDimensions () const
	Return the Kernel's dimensions (width, height) More...
void	setDimensions (lsst::geom::Extent2I dims)
void	setWidth (int width)
void	setHeight (int height)
int	getWidth () const
	Return the Kernel's width. More...
int	getHeight () const
	Return the Kernel's height. More...
lsst::geom::Point2I	getCtr () const
	Return index of kernel's center. More...
lsst::geom::Box2I	getBBox () const
	return parent bounding box, with XY0 = -center More...
unsigned int	getNKernelParameters () const
	Return the number of kernel parameters (0 if none) More...
int	getNSpatialParameters () const
	Return the number of spatial parameters (0 if not spatially varying) More...
SpatialFunctionPtr	getSpatialFunction (unsigned int index) const
	Return a clone of the specified spatial function (one component of the spatial model) More...
std::vector< SpatialFunctionPtr >	getSpatialFunctionList () const
	Return a list of clones of the spatial functions. More...
virtual double	getKernelParameter (unsigned int i) const
	Return a particular Kernel Parameter (no bounds checking). More...
virtual std::vector< double >	getKernelParameters () const
	Return the current kernel parameters. More...
lsst::geom::Box2I	growBBox (lsst::geom::Box2I const &bbox) const
	Given a bounding box for pixels one wishes to compute by convolving an image with this kernel, return the bounding box of pixels that must be accessed on the image to be convolved. More...
lsst::geom::Box2I	shrinkBBox (lsst::geom::Box2I const &bbox) const
	Given a bounding box for an image one wishes to convolve with this kernel, return the bounding box for the region of pixels that can be computed. More...
void	setCtr (lsst::geom::Point2I ctr)
	Set index of kernel's center. More...
std::vector< std::vector< double > >	getSpatialParameters () const
	Return the spatial parameters parameters (an empty vector if not spatially varying) More...
bool	isSpatiallyVarying () const
	Return true iff the kernel is spatially varying (has a spatial function) More...
void	setKernelParameters (std::vector< double > const &params)
	Set the kernel parameters of a spatially invariant kernel. More...
void	setKernelParameters (std::pair< double, double > const &params)
	Set the kernel parameters of a 2-component spatially invariant kernel. More...
void	setSpatialParameters (const std::vector< std::vector< double >> params)
	Set the parameters of all spatial functions. More...
void	computeKernelParametersFromSpatialModel (std::vector< double > &kernelParams, double x, double y) const
	Compute the kernel parameters at a specified point. More...
virtual std::string	toString (std::string const &prefix="") const
	Return a string representation of the kernel. More...
virtual void	computeCache (int const)
	Compute a cache of Kernel values, if desired. More...
virtual int	getCacheSize () const
	Get the current size of the kernel cache (0 if none or if caches not supported) More...
void	writeFits (std::string const &fileName, std::string const &mode="w") const
	Write the object to a regular FITS file. More...
void	writeFits (fits::MemFileManager &manager, std::string const &mode="w") const
	Write the object to a FITS image in memory. More...
void	writeFits (fits::Fits &fitsfile) const
	Write the object to an already-open FITS object. More...
virtual bool	isPersistable () const noexcept
	Return true if this particular object can be persisted using afw::table::io. More...

Static Public Member Functions
static std::shared_ptr< Kernel >	readFits (fits::Fits &fitsfile)
	Read an object from an already open FITS object. More...
static std::shared_ptr< Kernel >	readFits (std::string const &fileName, int hdu=fits::DEFAULT_HDU)
	Read an object from a regular FITS file. More...
static std::shared_ptr< Kernel >	readFits (fits::MemFileManager &manager, int hdu=fits::DEFAULT_HDU)
	Read an object from a FITS file in memory. More...
static std::shared_ptr< Kernel >	dynamicCast (std::shared_ptr< Persistable > const &ptr)
	Dynamically cast a shared_ptr. More...

Protected Types
using	OutputArchiveHandle = io::OutputArchiveHandle

Protected Member Functions
std::string	getPythonModule () const override
	Return the fully-qualified Python module that should be imported to guarantee that its factory is registered. More...
virtual void	setKernelParameter (unsigned int ind, double value) const
	Set one kernel parameter. More...
void	setKernelParametersFromSpatialModel (double x, double y) const
	Set the kernel parameters from the spatial model (if any). More...
virtual double	doComputeImage (lsst::afw::image::Image< Pixel > &image, bool doNormalize) const =0
	Low-level version of computeImage. More...
virtual std::string	getPersistenceName () const
	Return the unique name used to persist this object and look up its factory. More...
virtual void	write (OutputArchiveHandle &handle) const
	Write the object to one or more catalogs. More...

Protected Attributes
std::vector< SpatialFunctionPtr >	_spatialFunctionList

Private Member Functions
virtual void	_setKernelXY ()

Detailed Description

Kernels are used for convolution with MaskedImages and (eventually) Images.

Kernel is a virtual base class; it cannot be instantiated. The following notes apply to Kernel and to its subclasses.

The template type should usually be float or double; integer kernels should be used with caution because they do not normalize well.

The center pixel of a Kernel is at index: (width-1)/2, (height-1)/2. Thus it is centered along columns/rows if the kernel has an odd number of columns/rows and shifted 1/2 pixel towards 0 otherwise. A kernel should have an odd number of columns and rows unless it is intended to shift an image.

Spatially Varying Kernels

Kernels may optionally vary spatially (so long as they have any kernel parameters). To make a spatially varying kernel, specify a spatial function at construction (you cannot change your mind once the kernel is constructed). You must also specify a set of spatial parameters, and you may do this at construction and/or later by calling setSpatialParameters. The spatial parameters are a vector (one per kernel function parameter) of spatial function parameters. In other words the spatial parameters are a vector of vectors indexed as [kernel parameter][spatial parameter]. The one spatial function is used to compute the kernel parameters at a given spatial position by computing each kernel parameter using its associated vector of spatial function parameters.

The convolve function computes the spatial function at the pixel position (not index) of the image. See the convolve function for details.

Note that if a kernel is spatially varying then you may not set the kernel parameters directly; that is the job of the spatial function! However, you may change the spatial parameters at any time.

Design Notes

The basic design is to use the same kernel class for both spatially varying and spatially invariant kernels. The user either does or does not supply a function describing the spatial variation at creation time. In addition, analytic kernels are described by a user-supplied function of the same basic type as the spatial variation function.

Several other designs were considered, including: A) Use different classes for spatially varying and spatially invariant versions of each kernel. Thus instead of three basic kernel classes (FixedKernel, AnalyticKernel and LinearCombinationKernel) we would have five (since FixedKernel cannot be spatially varying). Robert Lupton argued that was a needless expansion of the class hiearchy and I agreed. B) Construct analytic kernels by defining a subclass of AnalyticKernel that is specific to the desired functional (e.g. GaussianAnalyticKernel). If spatial models are handled the same way then this creates a serious proliferation of kernel classes (even if we only have two different spatial models, e.g. polynomial and Chebyshev polynomial). I felt it made more sense to define the spatial model by some kind of function class (often called a "functor"), and since we needed such a class, I chose to use it for the analytic kernel as well.

However, having a separate function class does introduce some potential inefficiencies. If a function is part of the class it can potentially be evaluated more quickly than calling a function for each pixel or spatial position.

A possible variant on the current design is to define the spatial model and analytic kernel by specifying the functions as template parameters. This has the potential to regain some efficiency in evaluating the functions. However, it would be difficult or impossible to pre-instantiate the desired template classes, a requirement of the LSST coding standards.

Definition at line 110 of file Kernel.h.

Member Typedef Documentation

kernel_fill_factor

using lsst::afw::math::Kernel::kernel_fill_factor = generic_kernel_tag

Definition at line 118 of file Kernel.h.

NullSpatialFunction

using lsst::afw::math::Kernel::NullSpatialFunction = lsst::afw::math::NullFunction2<double>

Definition at line 115 of file Kernel.h.

OutputArchiveHandle

using lsst::afw::table::io::Persistable::OutputArchiveHandle = io::OutputArchiveHandle

protectedinherited

Definition at line 108 of file Persistable.h.

Pixel

using lsst::afw::math::Kernel::Pixel = double

Definition at line 112 of file Kernel.h.

SpatialFunction

using lsst::afw::math::Kernel::SpatialFunction = lsst::afw::math::Function2<double>

Definition at line 114 of file Kernel.h.

SpatialFunctionPtr

using lsst::afw::math::Kernel::SpatialFunctionPtr = std::shared_ptr<lsst::afw::math::Function2<double> >

Definition at line 113 of file Kernel.h.

Constructor & Destructor Documentation

Kernel() [1/5]

lsst::afw::math::Kernel::Kernel ( )

explicit

Construct a null Kernel of size 0,0.

A null constructor is primarily intended for persistence.

Definition at line 49 of file Kernel.cc.

: _spatialFunctionList(), _width(0), _height(0), _ctrX(0), _ctrY(0), _nKernelParams(0) {}

Kernel() [2/5]

lsst::afw::math::Kernel::Kernel ( int  width, int  height, unsigned int  nKernelParams, SpatialFunction const &  spatialFunction = NullSpatialFunction()  )

explicit

Construct a spatially invariant Kernel or a spatially varying Kernel with one spatial function that is duplicated as needed.

Parameters

width	number of columns
height	number of height
nKernelParams	number of kernel parameters
spatialFunction	spatial function, or NullSpatialFunction() if none specified

Exceptions

lsst::pex::exceptions::InvalidParameterError	if a spatial function is specified and the kernel has no parameters.
lsst::pex::exceptions::InvalidParameterError	if a width or height < 1

Definition at line 51 of file Kernel.cc.

        : _spatialFunctionList(),
          _width(width),
          _height(height),
          _ctrX((width - 1) / 2),
          _ctrY((height - 1) / 2),
          _nKernelParams(nKernelParams) {
    if ((width < 1) || (height < 1)) {
        std::ostringstream os;
        os << "kernel height = " << height << " and/or width = " << width << " < 1";
        throw LSST_EXCEPT(pexExcept::InvalidParameterError, os.str());
    }
    if (dynamic_cast<const NullSpatialFunction *>(&spatialFunction)) {
        // spatialFunction is not really present
    } else {
        if (nKernelParams == 0) {
            throw LSST_EXCEPT(pexExcept::InvalidParameterError, "Kernel function has no parameters");
        }
        for (unsigned int ii = 0; ii < nKernelParams; ++ii) {
            SpatialFunctionPtr spatialFunctionCopy = spatialFunction.clone();
            this->_spatialFunctionList.push_back(spatialFunctionCopy);
        }
    }
}

Kernel() [3/5]

lsst::afw::math::Kernel::Kernel ( int  width, int  height, const std::vector< SpatialFunctionPtr >  spatialFunctionList  )

explicit

Construct a spatially varying Kernel with a list of spatial functions (one per kernel parameter)

Note: if the list of spatial functions is empty then the kernel is not spatially varying.

Parameters

width	number of columns
height	number of height
spatialFunctionList	list of spatial function, one per kernel parameter

Exceptions

lsst::pex::exceptions::InvalidParameterError

if a width or height < 1

Definition at line 90 of file Kernel.cc.

        : _width(width),
          _height(height),
          _ctrX(width / 2),
          _ctrY(height / 2),
          _nKernelParams(spatialFunctionList.size()) {
    if ((width < 1) || (height < 1)) {
        std::ostringstream os;
        os << "kernel height = " << height << " and/or width = " << width << " < 1";
        throw LSST_EXCEPT(pexExcept::InvalidParameterError, os.str());
    }
    for (auto const &ii : spatialFunctionList) {
        SpatialFunctionPtr spatialFunctionCopy = ii->clone();
        this->_spatialFunctionList.push_back(spatialFunctionCopy);
    }
}

Kernel() [4/5]

lsst::afw::math::Kernel::Kernel ( const Kernel &  )

delete

Kernel() [5/5]

lsst::afw::math::Kernel::Kernel ( Kernel &&  )

delete

~Kernel()

lsst::afw::math::Kernel::~Kernel ( )

overridedefault

Member Function Documentation

_setKernelXY()

virtual void lsst::afw::math::Kernel::_setKernelXY ( )

inlineprivatevirtual

Reimplemented in lsst::afw::math::SeparableKernel.

Definition at line 459 of file Kernel.h.

{}

clone()

virtual std::shared_ptr<Kernel> lsst::afw::math::Kernel::clone ( ) const

pure virtual

Return a pointer to a deep copy of this kernel.

This kernel exists instead of a copy constructor so one can obtain a copy of an actual kernel instead of a useless copy of the base class.

Every kernel subclass must override this method.

Returns

a pointer to a deep copy of the kernel

Implemented in lsst::afw::math::NearestWarpingKernel, lsst::afw::math::BilinearWarpingKernel, lsst::afw::math::LanczosWarpingKernel, lsst::afw::math::SeparableKernel, lsst::afw::math::LinearCombinationKernel, lsst::afw::math::DeltaFunctionKernel, lsst::afw::math::AnalyticKernel, and lsst::afw::math::FixedKernel.

computeCache()

virtual void lsst::afw::math::Kernel::computeCache ( int const  )

inlinevirtual

Compute a cache of Kernel values, if desired.

Warning

: few kernel classes actually support this, in which case this is a no-op and getCacheSize always returns 0.

Reimplemented in lsst::afw::math::SeparableKernel.

Definition at line 397 of file Kernel.h.

      {}

computeImage()

double lsst::afw::math::Kernel::computeImage	(	lsst::afw::image::Image< Pixel > &	image,
		bool	doNormalize,
		double	x = 0.0,
		double	y = 0.0
	)		const

Compute an image (pixellized representation of the kernel) in place.

Parameters

image	image whose pixels are to be set (output); xy0 of the image will be set to -kernel.getCtr()
doNormalize	normalize the image (so sum is 1)?
x	x (column position) at which to compute spatial function
y	y (row position) at which to compute spatial function

Returns

The kernel sum

Exceptions

lsst::pex::exceptions::InvalidParameterError	if the image is the wrong size
lsst::pex::exceptions::OverflowError	if doNormalize is true and the kernel sum is exactly 0

Note

computeNewImage has been retired; it doesn't need to be a member

Definition at line 76 of file Kernel.cc.

                                                                                                {
    if (image.getDimensions() != this->getDimensions()) {
        std::ostringstream os;
        os << "image dimensions = ( " << image.getWidth() << ", " << image.getHeight() << ") != ("
           << this->getWidth() << ", " << this->getHeight() << ") = kernel dimensions";
        throw LSST_EXCEPT(pexExcept::InvalidParameterError, os.str());
    }
    image.setXY0(-_ctrX, -_ctrY);
    if (this->isSpatiallyVarying()) {
        this->setKernelParametersFromSpatialModel(x, y);
    }
    return doComputeImage(image, doNormalize);
}

computeKernelParametersFromSpatialModel()

void lsst::afw::math::Kernel::computeKernelParametersFromSpatialModel	(	std::vector< double > &	kernelParams,
		double	x,
		double	y
	)		const

Compute the kernel parameters at a specified point.

Warning: this is a low-level function that assumes kernelParams is the right length. It will fail in unpredictable ways if that condition is not met.

Definition at line 135 of file Kernel.cc.

                                                                     {
    std::vector<double>::iterator paramIter = kernelParams.begin();
    std::vector<SpatialFunctionPtr>::const_iterator funcIter = _spatialFunctionList.begin();
    for (; funcIter != _spatialFunctionList.end(); ++funcIter, ++paramIter) {
        *paramIter = (*(*funcIter))(x, y);
    }
}

doComputeImage()

virtual double lsst::afw::math::Kernel::doComputeImage ( lsst::afw::image::Image< Pixel > &  image, bool  doNormalize  ) const

protectedpure virtual

Low-level version of computeImage.

Before this is called the image dimensions are checked, the image's xy0 is set and the kernel's parameters are set. This routine sets the pixels, including normalization if requested.

Parameters

image	image whose pixels are to be set (output)
doNormalize	normalize the image (so sum is 1)?

Returns

The kernel sum

Implemented in lsst::afw::math::SeparableKernel, lsst::afw::math::LinearCombinationKernel, lsst::afw::math::DeltaFunctionKernel, lsst::afw::math::AnalyticKernel, and lsst::afw::math::FixedKernel.

dynamicCast()

template std::shared_ptr< meas::extensions::psfex::PsfexPsf > lsst::afw::table::io::PersistableFacade< Kernel >::dynamicCast ( std::shared_ptr< Persistable > const &  ptr )

staticinherited

Dynamically cast a shared_ptr.

Dynamically cast a shared pointer and raise on failure.

You must provide an explicit template instantiation in the .cc file for each class that inherits from PersistableFacade. Designed to work around RTTI issues on macOS with hidden symbols;

Exceptions

lsst::pex::exceptions::LogicError

if the cast fails

param[in] ptr The pointer to be cast.

Returns

The cast pointer.

Exceptions

lsst::pex::exceptions::TypeError

If the dynamic cast fails.

Definition at line 218 of file Persistable.cc.

                                                                                        {
    auto result = std::dynamic_pointer_cast<T>(ptr);
    if (!result) {
        throw LSST_EXCEPT(pex::exceptions::TypeError, "Dynamic pointer cast failed");
    }
    return result;
}

getBBox()

lsst::geom::Box2I lsst::afw::math::Kernel::getBBox ( ) const

inline

return parent bounding box, with XY0 = -center

Definition at line 239 of file Kernel.h.

                                         {
        return lsst::geom::Box2I(lsst::geom::Point2I(-_ctrX, -_ctrY), lsst::geom::Extent2I(_width, _height));
    }

getCacheSize()

virtual int lsst::afw::math::Kernel::getCacheSize ( ) const

inlinevirtual

Get the current size of the kernel cache (0 if none or if caches not supported)

Reimplemented in lsst::afw::math::SeparableKernel.

Definition at line 403 of file Kernel.h.

{ return 0; };

getCtr()

lsst::geom::Point2I lsst::afw::math::Kernel::getCtr ( ) const

inline

Return index of kernel's center.

Definition at line 234 of file Kernel.h.

{ return lsst::geom::Point2I(_ctrX, _ctrY); }

getDimensions()

lsst::geom::Extent2I const lsst::afw::math::Kernel::getDimensions ( ) const

inline

Return the Kernel's dimensions (width, height)

Definition at line 212 of file Kernel.h.

{ return lsst::geom::Extent2I(_width, _height); }

getHeight()

int lsst::afw::math::Kernel::getHeight ( ) const

inline

Return the Kernel's height.

Definition at line 229 of file Kernel.h.

{ return _height; }

getKernelParameter()

virtual double lsst::afw::math::Kernel::getKernelParameter ( unsigned int  i ) const

inlinevirtual

Return a particular Kernel Parameter (no bounds checking).

This version is slow, but specialisations may be faster

Reimplemented in lsst::afw::math::SeparableKernel.

Definition at line 277 of file Kernel.h.

{ return getKernelParameters()[i]; }

getKernelParameters()

std::vector< double > lsst::afw::math::Kernel::getKernelParameters ( ) const

virtual

Return the current kernel parameters.

If the kernel is spatially varying then the parameters are those last computed. See also computeKernelParametersFromSpatialModel. If there are no kernel parameters then returns an empty vector.

Reimplemented in lsst::afw::math::SeparableKernel, lsst::afw::math::LinearCombinationKernel, and lsst::afw::math::AnalyticKernel.

Definition at line 165 of file Kernel.cc.

{ return std::vector<double>(); }

getNKernelParameters()

unsigned int lsst::afw::math::Kernel::getNKernelParameters ( ) const

inline

Return the number of kernel parameters (0 if none)

Definition at line 246 of file Kernel.h.

{ return _nKernelParams; }

getNSpatialParameters()

int lsst::afw::math::Kernel::getNSpatialParameters ( ) const

inline

Return the number of spatial parameters (0 if not spatially varying)

Definition at line 251 of file Kernel.h.

                                             {
        return this->isSpatiallyVarying() ? _spatialFunctionList[0]->getNParameters() : 0;
    }

getPersistenceName()

std::string lsst::afw::table::io::Persistable::getPersistenceName ( ) const

protectedvirtualinherited

Return the unique name used to persist this object and look up its factory.

Must be less than ArchiveIndexSchema::MAX_NAME_LENGTH characters.

Reimplemented in lsst::meas::modelfit::Mixture, lsst::meas::algorithms::WarpedPsf, lsst::meas::algorithms::SingleGaussianPsf, lsst::meas::algorithms::KernelPsf, lsst::meas::algorithms::DoubleGaussianPsf, lsst::meas::algorithms::CoaddPsf, lsst::meas::algorithms::CoaddBoundedField, lsst::afw::typehandling::StorableHelper< Base >, lsst::afw::math::WarpingControl, lsst::afw::math::NearestWarpingKernel, lsst::afw::math::BilinearWarpingKernel, lsst::afw::math::LanczosWarpingKernel, lsst::afw::math::TransformBoundedField, lsst::afw::math::ProductBoundedField, lsst::afw::math::PixelAreaBoundedField, lsst::afw::math::LinearCombinationKernel, lsst::afw::math::DeltaFunctionKernel, lsst::afw::math::AnalyticKernel, lsst::afw::math::FixedKernel, lsst::afw::math::Chebyshev1Function2< ReturnT >, lsst::afw::math::PolynomialFunction2< ReturnT >, lsst::afw::math::DoubleGaussianFunction2< ReturnT >, lsst::afw::math::GaussianFunction2< ReturnT >, lsst::afw::math::ChebyshevBoundedField, lsst::afw::image::VisitInfo, lsst::afw::image::PhotoCalib, lsst::afw::image::CoaddInputs, lsst::afw::geom::Transform< FromEndpoint, ToEndpoint >, lsst::afw::geom::Transform< afw::geom::Point2Endpoint, afw::geom::GenericEndpoint >, lsst::afw::geom::SkyWcs, lsst::afw::geom::polygon::Polygon, lsst::afw::detection::HeavyFootprint< ImagePixelT, MaskPixelT, VariancePixelT >, lsst::afw::detection::GaussianPsf, lsst::afw::detection::Footprint, lsst::afw::cameraGeom::DetectorCollection, and lsst::afw::image::FilterLabel.

Definition at line 34 of file Persistable.cc.

{ return std::string(); }

getPythonModule()

std::string lsst::afw::math::Kernel::getPythonModule ( ) const

overrideprotectedvirtual

Return the fully-qualified Python module that should be imported to guarantee that its factory is registered.

Must be less than ArchiveIndexSchema::MAX_MODULE_LENGTH characters.

Will be ignored if empty.

Reimplemented from lsst::afw::table::io::Persistable.

Reimplemented in lsst::afw::math::NearestWarpingKernel, lsst::afw::math::BilinearWarpingKernel, and lsst::afw::math::LanczosWarpingKernel.

Definition at line 224 of file Kernel.cc.

{ return "lsst.afw.math"; }

getSpatialFunction()

Kernel::SpatialFunctionPtr lsst::afw::math::Kernel::getSpatialFunction

(

unsigned int

index

)

const

Return a clone of the specified spatial function (one component of the spatial model)

Parameters

index

index of desired spatial function; must be in range [0, number spatial parameters - 1]

Returns

a shared pointer to a spatial function. The function is a deep copy, so setting its parameters has no effect on the kernel.

Exceptions

lsst::pex::exceptions::InvalidParameterError	if kernel not spatially varying
lsst::pex::exceptions::InvalidParameterError	if index out of range

Definition at line 144 of file Kernel.cc.

                                                                            {
    if (index >= _spatialFunctionList.size()) {
        if (!this->isSpatiallyVarying()) {
            throw LSST_EXCEPT(pexExcept::InvalidParameterError, "kernel is not spatially varying");
        } else {
            std::ostringstream errStream;
            errStream << "index = " << index << "; must be < , " << _spatialFunctionList.size();
            throw LSST_EXCEPT(pexExcept::InvalidParameterError, errStream.str());
        }
    }
    return _spatialFunctionList[index]->clone();
}

getSpatialFunctionList()

std::vector< Kernel::SpatialFunctionPtr > lsst::afw::math::Kernel::getSpatialFunctionList

(

)

const

Return a list of clones of the spatial functions.

Returns

a list of shared pointers to spatial functions. The functions are deep copies, so setting their parameters has no effect on the kernel.

Definition at line 157 of file Kernel.cc.

                                                                         {
    std::vector<SpatialFunctionPtr> spFuncCopyList;
    for (auto const &spFuncIter : _spatialFunctionList) {
        spFuncCopyList.push_back((*spFuncIter).clone());
    }
    return spFuncCopyList;
}

getSpatialParameters()

std::vector<std::vector<double> > lsst::afw::math::Kernel::getSpatialParameters ( ) const

inline

Return the spatial parameters parameters (an empty vector if not spatially varying)

Definition at line 321 of file Kernel.h.

                                                                     {
        std::vector<std::vector<double>> spatialParams;
        std::vector<SpatialFunctionPtr>::const_iterator spFuncIter = _spatialFunctionList.begin();
        for (; spFuncIter != _spatialFunctionList.end(); ++spFuncIter) {
            spatialParams.push_back((*spFuncIter)->getParameters());
        }
        return spatialParams;
    }

getWidth()

int lsst::afw::math::Kernel::getWidth ( ) const

inline

Return the Kernel's width.

Definition at line 224 of file Kernel.h.

{ return _width; }

growBBox()

lsst::geom::Box2I lsst::afw::math::Kernel::growBBox

(

lsst::geom::Box2I const &

bbox

)

const

Given a bounding box for pixels one wishes to compute by convolving an image with this kernel, return the bounding box of pixels that must be accessed on the image to be convolved.

Thus the box shifted by -kernel.getCtr() and its size is expanded by kernel.getDimensions()-1.

Returns

the bbox expanded by the kernel.

Definition at line 167 of file Kernel.cc.

                                                              {
    return lsst::geom::Box2I(
            lsst::geom::Point2I(bbox.getMin() - lsst::geom::Extent2I(getCtr())),
            lsst::geom::Extent2I(bbox.getDimensions() + getDimensions() - lsst::geom::Extent2I(1, 1)));
}

isPersistable()

virtual bool lsst::afw::table::io::Persistable::isPersistable ( ) const

inlinevirtualnoexceptinherited

Return true if this particular object can be persisted using afw::table::io.

Reimplemented in lsst::meas::modelfit::Mixture, lsst::meas::extensions::psfex::PsfexPsf, lsst::meas::algorithms::WarpedPsf, lsst::meas::algorithms::SingleGaussianPsf, lsst::meas::algorithms::KernelPsf, lsst::meas::algorithms::DoubleGaussianPsf, lsst::meas::algorithms::CoaddPsf, lsst::meas::algorithms::CoaddBoundedField, lsst::afw::typehandling::StorableHelper< Base >, lsst::afw::math::WarpingControl, lsst::afw::math::NearestWarpingKernel, lsst::afw::math::BilinearWarpingKernel, lsst::afw::math::LanczosWarpingKernel, lsst::afw::math::TransformBoundedField, lsst::afw::math::ProductBoundedField, lsst::afw::math::PixelAreaBoundedField, lsst::afw::math::LinearCombinationKernel, lsst::afw::math::DeltaFunctionKernel, lsst::afw::math::AnalyticKernel, lsst::afw::math::FixedKernel, lsst::afw::math::Chebyshev1Function2< ReturnT >, lsst::afw::math::PolynomialFunction2< ReturnT >, lsst::afw::math::DoubleGaussianFunction2< ReturnT >, lsst::afw::math::GaussianFunction2< ReturnT >, lsst::afw::math::ChebyshevBoundedField, lsst::afw::image::VisitInfo, lsst::afw::image::PhotoCalib, lsst::afw::image::FilterLabel, lsst::afw::image::CoaddInputs, lsst::afw::image::ApCorrMap, lsst::afw::geom::Transform< FromEndpoint, ToEndpoint >, lsst::afw::geom::Transform< afw::geom::Point2Endpoint, afw::geom::GenericEndpoint >, lsst::afw::geom::SpanSet, lsst::afw::geom::SkyWcs, lsst::afw::geom::polygon::Polygon, lsst::afw::detection::GaussianPsf, lsst::afw::detection::Footprint, lsst::afw::cameraGeom::TransformMap, lsst::afw::cameraGeom::DetectorCollection, lsst::afw::cameraGeom::Detector, and lsst::afw::cameraGeom::Camera.

Definition at line 102 of file Persistable.h.

{ return false; }

isSpatiallyVarying()

bool lsst::afw::math::Kernel::isSpatiallyVarying ( ) const

inline

Return true iff the kernel is spatially varying (has a spatial function)

Definition at line 333 of file Kernel.h.

{ return _spatialFunctionList.size() != 0; }

operator=() [1/2]

Kernel& lsst::afw::math::Kernel::operator= ( const Kernel &  )

delete

operator=() [2/2]

Kernel& lsst::afw::math::Kernel::operator= ( Kernel &&  )

delete

readFits() [1/3]

static std::shared_ptr<Kernel > lsst::afw::table::io::PersistableFacade< Kernel >::readFits ( fits::Fits &  fitsfile )

inlinestaticinherited

Read an object from an already open FITS object.

Parameters

[in]

fitsfile

FITS object to read from, already positioned at the desired HDU.

Definition at line 183 of file Persistable.h.

                                                         {
        return dynamicCast(Persistable::_readFits(fitsfile));
    }

readFits() [2/3]

static std::shared_ptr<Kernel > lsst::afw::table::io::PersistableFacade< Kernel >::readFits ( fits::MemFileManager &  manager, int  hdu = fits::DEFAULT_HDU  )

inlinestaticinherited

Read an object from a FITS file in memory.

Parameters

[in]	manager	Manager for the memory to read from.
[in]	hdu	HDU to read, where 0 is the primary. The special value of afw::fits::DEFAULT_HDU skips the primary HDU if it is empty.

Definition at line 205 of file Persistable.h.

                                                                                             {
        return dynamicCast(Persistable::_readFits(manager, hdu));
    }

readFits() [3/3]

static std::shared_ptr<Kernel > lsst::afw::table::io::PersistableFacade< Kernel >::readFits ( std::string const &  fileName, int  hdu = fits::DEFAULT_HDU  )

inlinestaticinherited

Read an object from a regular FITS file.

Parameters

[in]	fileName	Name of the file to read.
[in]	hdu	HDU to read, where 0 is the primary. The special value of afw::fits::DEFAULT_HDU skips the primary HDU if it is empty.

Definition at line 194 of file Persistable.h.

                                                                                           {
        return dynamicCast(Persistable::_readFits(fileName, hdu));
    }

resized()

virtual std::shared_ptr<Kernel> lsst::afw::math::Kernel::resized ( int  width, int  height  ) const

pure virtual

Return a pointer to a clone with specified kernel dimensions.

Parameters

width	Number of columns in pixels
height	Number of rows in pixels

Returns

a pointer to a clone with new dimensions.

Must be implemented by derived classes.

Implemented in lsst::afw::math::SeparableKernel, lsst::afw::math::LinearCombinationKernel, lsst::afw::math::DeltaFunctionKernel, lsst::afw::math::AnalyticKernel, and lsst::afw::math::FixedKernel.

setCtr()

void lsst::afw::math::Kernel::setCtr ( lsst::geom::Point2I  ctr )

inline

Set index of kernel's center.

Definition at line 312 of file Kernel.h.

                                            {
        _ctrX = ctr.getX();
        _ctrY = ctr.getY();
        _setKernelXY();
    }

setDimensions()

void lsst::afw::math::Kernel::setDimensions ( lsst::geom::Extent2I  dims )

inline

Definition at line 214 of file Kernel.h.

                                              {
        _width = dims.getX();
        _height = dims.getY();
    }

setHeight()

void lsst::afw::math::Kernel::setHeight ( int  height )

inline

Definition at line 219 of file Kernel.h.

{ _height = height; }

setKernelParameter()

void lsst::afw::math::Kernel::setKernelParameter ( unsigned int  ind, double  value  ) const

protectedvirtual

Set one kernel parameter.

Classes that have kernel parameters must subclass this function.

This function is marked "const", despite modifying unimportant internals, so that computeImage can be const.

Exceptions

lsst::pex::exceptions::InvalidParameterError

always (unless subclassed)

Reimplemented in lsst::afw::math::NearestWarpingKernel, lsst::afw::math::BilinearWarpingKernel, lsst::afw::math::LanczosWarpingKernel, lsst::afw::math::SeparableKernel, lsst::afw::math::LinearCombinationKernel, and lsst::afw::math::AnalyticKernel.

Definition at line 213 of file Kernel.cc.

                                                          {
    throw LSST_EXCEPT(pexExcept::InvalidParameterError, "Kernel has no kernel parameters");
}

setKernelParameters() [1/2]

void lsst::afw::math::Kernel::setKernelParameters ( std::pair< double, double > const &  params )

inline

Set the kernel parameters of a 2-component spatially invariant kernel.

Warning

This is a low-level method intended for maximum efficiency when using warping kernels. No error checking is performed. Use the std::vector<double> form if you want safety.

Definition at line 363 of file Kernel.h.

                                                                           {
        this->setKernelParameter(0, params.first);
        this->setKernelParameter(1, params.second);
    }

setKernelParameters() [2/2]

void lsst::afw::math::Kernel::setKernelParameters ( std::vector< double > const &  params )

inline

Set the kernel parameters of a spatially invariant kernel.

Exceptions

lsst::pex::exceptions::RuntimeError	if the kernel has a spatial function
lsst::pex::exceptions::InvalidParameterError	if the params vector is the wrong length

Definition at line 341 of file Kernel.h.

                                                                     {
        if (this->isSpatiallyVarying()) {
            throw LSST_EXCEPT(lsst::pex::exceptions::RuntimeError, "Kernel is spatially varying");
        }
        const unsigned int nParams = this->getNKernelParameters();
        if (nParams != params.size()) {
            throw LSST_EXCEPT(lsst::pex::exceptions::InvalidParameterError,
                              (boost::format("Number of parameters is wrong, saw %d expected %d") % nParams %
                               params.size())
                                      .str());
        }
        for (unsigned int ii = 0; ii < nParams; ++ii) {
            this->setKernelParameter(ii, params[ii]);
        }
    }

setKernelParametersFromSpatialModel()

void lsst::afw::math::Kernel::setKernelParametersFromSpatialModel ( double  x, double  y  ) const

protected

Set the kernel parameters from the spatial model (if any).

This function has no effect if there is no spatial model.

This function is marked "const", despite modifying unimportant internals, so that computeImage can be const.

Definition at line 217 of file Kernel.cc.

                                                                         {
    std::vector<SpatialFunctionPtr>::const_iterator funcIter = _spatialFunctionList.begin();
    for (int ii = 0; funcIter != _spatialFunctionList.end(); ++funcIter, ++ii) {
        this->setKernelParameter(ii, (*(*funcIter))(x, y));
    }
}

setSpatialParameters()

void lsst::afw::math::Kernel::setSpatialParameters

(

const std::vector< std::vector< double >>

params

)

Set the parameters of all spatial functions.

Params is indexed as [kernel parameter][spatial parameter]

Exceptions

lsst::pex::exceptions::InvalidParameterError

if params is the wrong shape (if this exception is thrown then no parameters are changed)

Definition at line 110 of file Kernel.cc.

                                                                            {
    // Check params size before changing anything
    unsigned int nKernelParams = this->getNKernelParameters();
    if (params.size() != nKernelParams) {
        throw LSST_EXCEPT(
                pexExcept::InvalidParameterError,
                (boost::format("params has %d entries instead of %d") % params.size() % nKernelParams).str());
    }
    unsigned int nSpatialParams = this->getNSpatialParameters();
    for (unsigned int ii = 0; ii < nKernelParams; ++ii) {
        if (params[ii].size() != nSpatialParams) {
            throw LSST_EXCEPT(pexExcept::InvalidParameterError,
                              (boost::format("params[%d] has %d entries instead of %d") % ii %
                               params[ii].size() % nSpatialParams)
                                      .str());
        }
    }
    // Set parameters
    if (nSpatialParams > 0) {
        for (unsigned int ii = 0; ii < nKernelParams; ++ii) {
            this->_spatialFunctionList[ii]->setParameters(params[ii]);
        }
    }
}

setWidth()

void lsst::afw::math::Kernel::setWidth ( int  width )

inline

Definition at line 218 of file Kernel.h.

{ _width = width; }

shrinkBBox()

lsst::geom::Box2I lsst::afw::math::Kernel::shrinkBBox

(

lsst::geom::Box2I const &

bbox

)

const

Given a bounding box for an image one wishes to convolve with this kernel, return the bounding box for the region of pixels that can be computed.

Thus the box shifted by kernel.getCtr() and its size is reduced by kernel.getDimensions()-1.

Returns

the bbox shrunk by the kernel.

Exceptions

lsst::pex::exceptions::InvalidParameterError

if the resulting box would have dimension < 1 in either axis

Definition at line 173 of file Kernel.cc.

                                                                {
    if ((bbox.getWidth() < getWidth()) || ((bbox.getHeight() < getHeight()))) {
        std::ostringstream os;
        os << "bbox dimensions = " << bbox.getDimensions() << " < (" << getWidth() << ", " << getHeight()
           << ") in one or both dimensions";
        throw LSST_EXCEPT(pexExcept::InvalidParameterError, os.str());
    }
    return lsst::geom::Box2I(
            lsst::geom::Point2I(bbox.getMin() + lsst::geom::Extent2I(getCtr())),
            lsst::geom::Extent2I(bbox.getWidth() + 1 - getWidth(), bbox.getHeight() + 1 - getHeight()));
}

toString()

std::string lsst::afw::math::Kernel::toString ( std::string const &  prefix = "" ) const

virtual

Return a string representation of the kernel.

Reimplemented in lsst::afw::math::SeparableKernel, lsst::afw::math::LinearCombinationKernel, lsst::afw::math::DeltaFunctionKernel, lsst::afw::math::AnalyticKernel, and lsst::afw::math::FixedKernel.

Definition at line 185 of file Kernel.cc.

                                                        {
    std::ostringstream os;
    os << prefix << "Kernel:" << std::endl;
    os << prefix << "..height, width: " << _height << ", " << _width << std::endl;
    os << prefix << "..ctr (X, Y): " << _ctrX << ", " << _ctrY << std::endl;
    os << prefix << "..nKernelParams: " << _nKernelParams << std::endl;
    os << prefix << "..isSpatiallyVarying: " << (this->isSpatiallyVarying() ? "True" : "False") << std::endl;
    if (this->isSpatiallyVarying()) {
        os << prefix << "..spatialFunctions:" << std::endl;
        for (auto const &spFuncPtr : _spatialFunctionList) {
            os << prefix << "...." << spFuncPtr->toString() << std::endl;
        }
    }
    return os.str();
}

write()

void lsst::afw::table::io::Persistable::write ( OutputArchiveHandle &  handle ) const

protectedvirtualinherited

Write the object to one or more catalogs.

The handle object passed to this function provides an interface for adding new catalogs and adding nested objects to the same archive (while checking for duplicates). See OutputArchiveHandle for more information.

Reimplemented in lsst::afw::typehandling::StorableHelper< Base >, lsst::afw::image::FilterLabel, lsst::meas::modelfit::Mixture, lsst::meas::algorithms::WarpedPsf, lsst::meas::algorithms::SingleGaussianPsf, lsst::meas::algorithms::KernelPsf, lsst::meas::algorithms::DoubleGaussianPsf, lsst::meas::algorithms::CoaddPsf, lsst::meas::algorithms::CoaddBoundedField, lsst::afw::math::WarpingControl, lsst::afw::math::NearestWarpingKernel, lsst::afw::math::BilinearWarpingKernel, lsst::afw::math::LanczosWarpingKernel, lsst::afw::math::TransformBoundedField, lsst::afw::math::ProductBoundedField, lsst::afw::math::PixelAreaBoundedField, lsst::afw::math::LinearCombinationKernel, lsst::afw::math::DeltaFunctionKernel, lsst::afw::math::AnalyticKernel, lsst::afw::math::FixedKernel, lsst::afw::math::ChebyshevBoundedField, lsst::afw::image::VisitInfo, lsst::afw::image::PhotoCalib, lsst::afw::image::CoaddInputs, lsst::afw::geom::Transform< FromEndpoint, ToEndpoint >, lsst::afw::geom::Transform< afw::geom::Point2Endpoint, afw::geom::GenericEndpoint >, lsst::afw::geom::SkyWcs, lsst::afw::geom::polygon::Polygon, lsst::afw::detection::HeavyFootprint< ImagePixelT, MaskPixelT, VariancePixelT >, lsst::afw::detection::GaussianPsf, lsst::afw::detection::Footprint, lsst::afw::cameraGeom::DetectorCollection, lsst::afw::cameraGeom::Camera, lsst::meas::extensions::psfex::PsfexPsf, lsst::afw::math::Chebyshev1Function2< ReturnT >, lsst::afw::math::PolynomialFunction2< ReturnT >, lsst::afw::math::DoubleGaussianFunction2< ReturnT >, and lsst::afw::math::GaussianFunction2< ReturnT >.

Definition at line 38 of file Persistable.cc.

                                                   {
    assert(!isPersistable());
    throw LSST_EXCEPT(pex::exceptions::LogicError,
                      "afw::table-based persistence is not supported for this object.");
}

writeFits() [1/3]

void lsst::afw::table::io::Persistable::writeFits ( fits::Fits &  fitsfile ) const

inherited

Write the object to an already-open FITS object.

Parameters

[in]

fitsfile

Open FITS object to write to.

Definition at line 18 of file Persistable.cc.

                                                    {
    OutputArchive archive;
    archive.put(this);
    archive.writeFits(fitsfile);
}

writeFits() [2/3]

void lsst::afw::table::io::Persistable::writeFits ( fits::MemFileManager &  manager, std::string const &  mode = "w"  ) const

inherited

Write the object to a FITS image in memory.

Parameters

[in]	manager	Name of the file to write to.
[in]	mode	If "w", any existing file with the given name will be overwritten. If "a", new HDUs will be appended to an existing file.

Definition at line 29 of file Persistable.cc.

                                                                                    {
    fits::Fits fitsfile(manager, mode, fits::Fits::AUTO_CLOSE | fits::Fits::AUTO_CHECK);
    writeFits(fitsfile);
}

writeFits() [3/3]

void lsst::afw::table::io::Persistable::writeFits ( std::string const &  fileName, std::string const &  mode = "w"  ) const

inherited

Write the object to a regular FITS file.

Parameters

[in]	fileName	Name of the file to write to.
[in]	mode	If "w", any existing file with the given name will be overwritten. If "a", new HDUs will be appended to an existing file.

Definition at line 24 of file Persistable.cc.

                                                                                  {
    fits::Fits fitsfile(fileName, mode, fits::Fits::AUTO_CLOSE | fits::Fits::AUTO_CHECK);
    writeFits(fitsfile);
}

Member Data Documentation

_spatialFunctionList

std::vector<SpatialFunctionPtr> lsst::afw::math::Kernel::_spatialFunctionList

protected

Definition at line 449 of file Kernel.h.

---

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

• /j/snowflake/release/lsstsw/stack/lsst-scipipe-0.7.0/Linux64/afw/22.0.1-32-g5ddfab5d3+60ce4897b0/include/lsst/afw/math/Kernel.h
• /j/snowflake/release/lsstsw/stack/lsst-scipipe-0.7.0/Linux64/afw/22.0.1-32-g5ddfab5d3+60ce4897b0/src/math/Kernel.cc