A shape where emission comes from only one direction. More...

#include <PointShape.h>

Inheritance diagram for casa::PointShape:

Public Member Functions
	PointShape ()
	The default PointShape is at the J2000 North Pole. More...

	PointShape (const casacore::MDirection &direction)
	Construct a point shape at the specified direction. More...

	PointShape (const PointShape &other)
	The copy constructor uses copy semantics. More...

virtual	~PointShape ()
	The destructor does nothing special. More...

PointShape &	operator= (const PointShape &other)
	The assignment operator uses copy semantics. More...

virtual ComponentType::Shape	type () const
	Return the type of shape. More...

virtual casacore::Double	sample (const casacore::MDirection &direction, const casacore::MVAngle &pixelLatSize, const casacore::MVAngle &pixelLongSize) const
	Calculate the proportion of the flux that is in a pixel of the specified size centered on the specified direction. More...

virtual void	sample (casacore::Vector< casacore::Double > &scale, const casacore::Vector< casacore::MDirection::MVType > &directions, const casacore::MDirection::Ref &refFrame, const casacore::MVAngle &pixelLatSize, const casacore::MVAngle &pixelLongSize) const
	Same as the previous function except that many directions can be sampled at once. More...

virtual casacore::DComplex	visibility (const casacore::Vector< casacore::Double > &uvw, const casacore::Double &frequency) const
	Return the Fourier transform of the component at the specified point in the spatial frequency domain. More...

virtual void	visibility (casacore::Vector< casacore::DComplex > &scale, const casacore::Matrix< casacore::Double > &uvw, const casacore::Double &frequency) const
	Same as the previous function except that many (u,v,w) points can be sampled at once. More...

virtual void	visibility (casacore::Matrix< casacore::DComplex > &scale, const casacore::Matrix< casacore::Double > &uvw, const casacore::Vector< casacore::Double > &frequency) const
	Same as above except with many frequencies. More...

virtual casacore::Bool	isSymmetric () const
	A point shape is symmetric so this function always returns true;. More...

virtual ComponentShape *	clone () const
	Return a pointer to a copy of this object upcast to a ComponentShape object. More...

virtual casacore::uInt	nParameters () const
	return the number of parameters in this shape and set/get them. More...

virtual void	setParameters (const casacore::Vector< casacore::Double > &newParms)

virtual casacore::Vector < casacore::Double >	parameters () const

virtual void	setErrors (const casacore::Vector< casacore::Double > &newParms)

virtual casacore::Vector < casacore::Double >	errors () const

virtual casacore::Vector < casacore::Double >	optParameters () const

virtual void	setOptParameters (const casacore::Vector< casacore::Double > &newOptParms)

virtual casacore::Bool	fromRecord (casacore::String &errorMessage, const casacore::RecordInterface &record)
	This functions convert between a casacore::Record and a PointShape. More...

virtual casacore::Bool	toRecord (casacore::String &errorMessage, casacore::RecordInterface &record) const
	Convert the class to an Record representation. More...

virtual casacore::Bool	convertUnit (casacore::String &, const casacore::RecordInterface &)
	Convert the parameters of the component to the specified units. More...

virtual casacore::Bool	ok () const
	casacore::Function which checks the internal data of this class for consistent values. More...

virtual const ComponentShape *	getPtr () const
	return a pointer to this object. More...

virtual casacore::String	sizeToString () const

Public Member Functions inherited from casa::ComponentShape
virtual	~ComponentShape ()

virtual const casacore::String &	ident () const
	Specify the identification of the record (e.g. More...

void	setRefDirection (const casacore::MDirection &newRefDir)

const casacore::MDirection &	refDirection () const

void	setRefDirectionError (const casacore::Quantum< casacore::Double > &newRefDirErrLat, const casacore::Quantum< casacore::Double > &newRefDirErrLong)

const casacore::Quantum < casacore::Double > &	refDirectionErrorLat () const

const casacore::Quantum < casacore::Double > &	refDirectionErrorLong () const

void	copyDirectionInfo (const ComponentShape &that)

virtual casacore::Vector < casacore::Double >	toPixel (const casacore::DirectionCoordinate &dirCoord) const

virtual casacore::Bool	fromPixel (const casacore::Vector< casacore::Double > &parameters, const casacore::DirectionCoordinate &dirCoord)

Public Member Functions inherited from casacore::RecordTransformable
virtual	~RecordTransformable ()
	The destructor must be virtual so that the destructor of derived classes is actually used. More...

virtual Bool	fromString (String &error, const String &inString)
	Initialise the class from a String representation. More...

Private Member Functions
casacore::Double	dirIsInPixel (casacore::Double longSize, casacore::Double latSize, casacore::Double nearSize, const casacore::MDirection::MVType &dirValue, const casacore::MDirection::MVType *compDirValue) const
	FInd out if a direction is located within a pixel. More...

Additional Inherited Members
Static Public Member Functions inherited from casa::ComponentShape
static ComponentType::Shape	getType (casacore::String &errorMessage, const casacore::RecordInterface &record)

Protected Member Functions inherited from casa::ComponentShape
	ComponentShape ()

	ComponentShape (const casacore::MDirection &direction)

	ComponentShape (const ComponentShape &other)

ComponentShape &	operator= (const ComponentShape &other)

Static Protected Member Functions inherited from casa::ComponentShape
static casacore::Bool	differentRefs (const casacore::MeasRef< casacore::MDirection > &ref1, const casacore::MeasRef< casacore::MDirection > &ref2)

static casacore::Bool	badError (const casacore::Quantum< casacore::Double > &quantum)

static casacore::Bool	fromAngQRecord (casacore::Quantum< casacore::Double > &returnValue, casacore::String &errorMessage, const casacore::String &fieldString, const casacore::RecordInterface &record)

Detailed Description

A shape where emission comes from only one direction.

Intended use:

Public interface

Review Status

Date Reviewed:: yyyy/mm/dd
Test programs:: tPointShape
Demo programs:: dPointShape

Prerequisite

ComponentShape

Synopsis

This class represents the shape of components where the emission comes from only one point in the sky.

This class like the other component shapes becomes more useful when used through the SkyComponent class, which incorporates the flux and spectral variation of the emission, or through the ComponentList class, which handles groups of SkyComponent objects.

For a point shape all the emission comes only from the reference direction which is specified in celestial co-ordinates, using a MDirection object. The direction can be specified both in the constructor or with the setRefDirection function.

The sample member functions are used to determine the proportion of flux the component at any point on the sky. For a point component this is either zero or one depending on whether the specified pixel contains the point source or not.

The visibility functions return the Fourier transform of the component at a specified spatial frequency. For a point shape the Fourier transform is a constant value. Hence these functions return one, regardless of the input parameters.

This class also contains functions (toRecord & fromRecord) which perform the conversion between Records and PointShape objects. These functions define how a PointShape object is represented in glish. The format of the record that is generated and accepted by these functions is:

c := [type = 'point',
direction = [type = 'direction',
refer = 'j2000',
m0 = [value = 0, unit = 'deg']
m1 = [value = 0, unit = 'deg']
]
]

The direction field contains a record representation of a direction measure and its format is defined in the Measures module. Its refer field defines the reference frame for the direction and the m0 and m1 fields define the latitude and longitude in that frame.

Example

Suppose I had an image of a region of the sky and we wanted to subtract a point source from it. This could be done as follows:

Construct a SkyComponent with to represent the point source
Project the component onto an image
Convolve the image by the point spread function
subtract the convolved model from the dirty image.

Shown below is the code to perform the first step in this process, ie construct the SkyComponent. This example is also available in the dPointShape.cc file. Note that it is more accurate to do subtraction of point components in the (u,v) domain

casacore::MDirection J1934_dir;
{ // get the right direction into J1934_dir
casacore::Quantity J1934_ra; casacore::MVAngle::read(J1934_ra, "19:39:");
casacore::Quantity J1934_dec; casacore::MVAngle::read(J1934_dec, "-63.43.");
J1934_dir = casacore::MDirection(J1934_ra, J1934_dec, casacore::MDirection::J2000);
}
{ // One way to construct the SkyComponent
SkyComponent J1934(ComponentType::POINT, ComponentType::CONSTANT_SPECTRUM);
J1934.shape().setRefDirection(J1934_dir);
J1934.flux() = Flux<casacore::Double>(6.28, 0.1, 0.15, 0.01);
printShape(J1934.shape());
}
{ // An alternative way to construct the SkyComponent
const Flux<casacore::Double> flux(6.28, 0.1, 0.15, 0.01);
const PointShape shape(J1934_dir);
const ConstantSpectrum spectrum;
SkyComponent component(flux, shape, spectrum);
printShape(component.shape());
}

Note how the member functions of the PointShape class (the setDirection function) are accessable through the shape function in the SkyComponent class. The printShape function is the example shown for the ComponentShape class.

To Do

Use Measures & Quanta in the interface to the visibility functions.

Definition at line 156 of file PointShape.h.

Constructor & Destructor Documentation

casa::PointShape::PointShape ( )

The default PointShape is at the J2000 North Pole.

casa::PointShape::PointShape ( const casacore::MDirection & direction )

Construct a point shape at the specified direction.

casa::PointShape::PointShape ( const PointShape & other )

The copy constructor uses copy semantics.

virtual casa::PointShape::~PointShape ( )

virtual

The destructor does nothing special.

Member Function Documentation

virtual ComponentShape* casa::PointShape::clone ( ) const

virtual

Return a pointer to a copy of this object upcast to a ComponentShape object.

The class that uses this function is responsible for deleting the pointer. This is used to implement a virtual copy constructor.

Public Member Functions

Private Member Functions

Additional Inherited Members