A disk model for the spatial distribution of emission. More...

#include <DiskShape.h>

Inheritance diagram for casa::DiskShape:

Public Member Functions
	DiskShape ()
	The default GaussianShape is at the J2000 North Pole with a width of 1 arc-min on both axes. More...

	DiskShape (const casacore::MDirection &direction, const casacore::Quantum< casacore::Double > &majorAxis, const casacore::Quantum< casacore::Double > &minorAxis, const casacore::Quantum< casacore::Double > &positionAngle)
	Construct a disk shape centred in the specified direction, specifying the widths & position angle. More...

	DiskShape (const casacore::MDirection &direction, const casacore::Quantum< casacore::Double > &width, const casacore::Double axialRatio, const casacore::Quantum< casacore::Double > &positionAngle)

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

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

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

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

virtual void	setWidthInRad (const casacore::Double majorAxis, const casacore::Double minorAxis, const casacore::Double positionAngle)
	set or return the width and orientation of the disk. More...

virtual casacore::Double	majorAxisInRad () const

virtual casacore::Double	minorAxisInRad () const

virtual casacore::Double	positionAngleInRad () const

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 specified size centered in 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 ComponentShape *	clone () const
	Return a pointer to a copy of this object upcast to a ComponentShape object. More...

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

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

virtual casacore::String	sizeToString () const
	Get the string containing the various size quantities of a component. More...

Public Member Functions inherited from casa::TwoSidedShape
virtual	~TwoSidedShape ()
	a virtual destructor is needed so that the actual destructor in the derived class will be used. More...

void	setWidth (const casacore::Quantum< casacore::Double > &majorAxis, const casacore::Quantum< casacore::Double > &minorAxis, const casacore::Quantum< casacore::Double > &positionAngle)
	set/get the width and orientation of the Shape. More...

void	setWidth (const casacore::Quantum< casacore::Double > &majorAxis, const casacore::Double axialRatio, const casacore::Quantum< casacore::Double > &positionAngle)

casacore::Quantum < casacore::Double >	majorAxis () const

casacore::Quantum < casacore::Double >	minorAxis () const

casacore::Quantum < casacore::Double >	positionAngle () const

casacore::Double	axialRatio () const

void	setErrors (const casacore::Quantum< casacore::Double > &majorAxisError, const casacore::Quantum< casacore::Double > &minorAxisError, const casacore::Quantum< casacore::Double > &positionAngleError)
	set/get the errors on the shape parameters. More...

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

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

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

casacore::Double	axialRatioError () const

virtual casacore::Bool	isSymmetric () const
	determine whether the shape is symmetric or not. More...

virtual casacore::uInt	nParameters () const
	set/get the shape parameters associated with this shape. 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 shape derived from this class. 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 &errorMessage, const casacore::RecordInterface &record)
	Convert the parameters of the component to the specified units. More...

virtual casacore::Vector < casacore::Double >	toPixel (const casacore::DirectionCoordinate &dirCoord) const
	Convert component shape to absolute pixels (longitude, latitude, major axis, minor axis, position angle [positive +x -> +y ; rad]) More...

virtual casacore::Bool	fromPixel (const casacore::Vector< casacore::Double > &parameters, const casacore::DirectionCoordinate &dirCoord)
	Fill the shape from the vector (longitude, latitude, major axis, minor axis, position angle [positive +x -> +y ; rad]). More...

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)

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	_area () const
	area of disk More...

casacore::Double	_calcSample (const casacore::MDirection::MVType &compDirValue, const casacore::MDirection::MVType &dirVal, const casacore::Double majRad, const casacore::Double minRad, const casacore::Double pixValue) const

casacore::Double	_calcVis (casacore::Double u, casacore::Double v, const casacore::Double factor) const

Static Private Member Functions
static void	_rotateVis (casacore::Double &u, casacore::Double &v, const casacore::Double cpa, const casacore::Double spa)

Private Attributes
casacore::Double	_majorAxis
	The parameters of the disk. More...

casacore::Double	_minorAxis

casacore::Double	_pa

casacore::Double	_recipArea

Additional Inherited Members
Static Public Member Functions inherited from casa::TwoSidedShape
static casacore::String	sizeToString (casacore::Quantity major, casacore::Quantity minor, casacore::Quantity posangle, casacore::Bool includeUncertainties=true, casacore::Quantity majorErr=0, casacore::Quantity minorErr=0, casacore::Quantity posanErr=0)
	casacore::Format the string containing the various size quantities of a component. More...

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::TwoSidedShape
	TwoSidedShape ()
	The constructors and assignment operator are protected as only derived classes should use them. More...

	TwoSidedShape (const casacore::MDirection &direction, const casacore::Unit &majorAxisUnit, const casacore::Unit &minorAxisUnit, const casacore::Unit &paUnit)

	TwoSidedShape (const TwoSidedShape &other)

TwoSidedShape &	operator= (const TwoSidedShape &other)

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 disk model for the spatial distribution of emission.

Intended use:

Public interface

Review Status

Date Reviewed:: yyyy/mm/dd
Test programs:: tDiskShape
Demo programs:: dTwoSidedShape

Prerequisite

TwoSidedShape

Synopsis

A DiskShape models the spatial distribution of radiation from the sky as a using a uniform brightness elliptical disk with user specified major axis width, minor axis width and position angle.

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

The reference direction is defined in celestial co-ordinates, using a MDirection object. It indicates where the centre of the disk is on the sky. The direction can be specified both in the constructor or with the setRefDirection function.

The width of the disk is defined as the angular diameter along the specified axis. The major axis has the larger width and is aligned North-South when the position angle is zero. A positive position angle moves the Northern side of the disk to the East. The axial ratio is the ratio of the minor to major axis widths. The major axis MUST not be smaller than the minor axis otherwise an casacore::AipsError is thrown.

These parameters of the disk (width, position angle, direction etc.) can be specified at construction time, using the *inRad functions or through functions, in the base classes. The base classes also implement functions for inter-converting this object into a record representation.

The flux, or integrated intensity, is always normalised to one. This class does not model the actual flux or its variation with frequency. It solely models the way the emission varies with position on the sky.

The sample member function is used to sample the component at any point on the sky. The scale factor calculated by this function is the proportion of the flux that is within a specified pixel size centered on the specified direction. This is not accurate for pixels which are partially covered by the disk. Ultimately this function will integrate the emission from the disk over the entire pixel but currently the returned flux will be either zero or a constant value with the returned value depending on whether the centre of the pixel in within the disk or not. This inaccuracy becomes more important when the pixel size become large compared to the disk width.

This class contains functions that return the Fourier transform of the disk at a specified spatial frequency. There are described more fully in the description of the visibility functions below.

Example

Shown below is code to construct a disk shaped model whose direction is always centred on the disk of Jupiter. Note that it is necessary to specify the observation time in order for the DiskShape class to be able to do the conversion into J2000 coordinates. This example is also available in the dTwoSidedShape.cc file.

{ // construct a model for Jupiter.
casacore::Quantity clk_time; casacore::MVTime::read(clk_time, "01-10-2000/12:59");
casacore::MEpoch obs_epoch(clk_time, casacore::MEpoch::UTC);
casacore::MeasFrame obs_frame(obs_epoch);
casacore::MDirection jupiter_dir(casacore::MVDirection(0), 
casacore::MDirection::Ref(casacore::MDirection::JUPITER, obs_frame));
DiskShape jupiter_shape;
jupiter_shape.setRefDirection(jupiter_dir);
jupiter_shape.setWidth(casacore::Quantity(4,"arcmin"), casacore::Quantity(3.9,"arcmin"),
casacore::Quantity(3, "deg"));
printShape(jupiter_shape);
casacore::MDirection sample_dir(casacore::MVDirection(1.218, 0.37), casacore::MDirection::J2000);
if (jupiter_shape.sample(sample_dir, casacore::MVAngle(0.1)) > 0.0) {
cout << "The position in J2000 coordinates is near: " 
<< sample_dir.getAngle("deg") << endl;
}
}

The printShape function is the example shown for the TwoSidedShape class.

To Do

Use Measures & Quanta in the interface to the visibility functions.
Use a better way of integrating over the pixel area in the sample function.
Ensure that the position angle is always between zero and 180 degrees, and that the widths are always positive.

Definition at line 149 of file DiskShape.h.

Constructor & Destructor Documentation

casa::DiskShape::DiskShape ( )

The default GaussianShape is at the J2000 North Pole with a width of 1 arc-min on both axes.

casa::DiskShape::DiskShape	(	const casacore::MDirection &	direction,
		const casacore::Quantum< casacore::Double > &	majorAxis,
		const casacore::Quantum< casacore::Double > &	minorAxis,
		const casacore::Quantum< casacore::Double > &	positionAngle
	)

Construct a disk shape centred in the specified direction, specifying the widths & position angle.

casa::DiskShape::DiskShape	(	const casacore::MDirection &	direction,
		const casacore::Quantum< casacore::Double > &	width,
		const casacore::Double	axialRatio,
		const casacore::Quantum< casacore::Double > &	positionAngle
	)

casa::DiskShape::DiskShape ( const DiskShape & other )

The copy constructor uses copy semantics.

virtual casa::DiskShape::~DiskShape ( )

virtual

The destructor does nothing special.

Member Function Documentation

casacore::Double casa::DiskShape::_area ( ) const

private

area of disk

casacore::Double casa::DiskShape::_calcSample	(	const casacore::MDirection::MVType &	compDirValue,
		const casacore::MDirection::MVType &	dirVal,
		const casacore::Double	majRad,
		const casacore::Double	minRad,
		const casacore::Double	pixValue
	)		const

private

casacore::Double casa::DiskShape::_calcVis	(	casacore::Double	u,
		casacore::Double	v,
		const casacore::Double	factor
	)		const

private

static void casa::DiskShape::_rotateVis	(	casacore::Double &	u,
		casacore::Double &	v,
		const casacore::Double	cpa,
		const casacore::Double	spa
	)

staticprivate

virtual ComponentShape* casa::DiskShape::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.

Implements casa::TwoSidedShape.

virtual const ComponentShape* casa::DiskShape::getPtr ( ) const

virtual

return a pointer to this object.

Implements casa::ComponentShape.

virtual casacore::Double casa::DiskShape::majorAxisInRad ( ) const

virtual

Implements casa::TwoSidedShape.

virtual casacore::Double casa::DiskShape::minorAxisInRad ( ) const

virtual

Implements casa::TwoSidedShape.

virtual casacore::Bool casa::DiskShape::ok ( ) const

virtual

casacore::Function which checks the internal data of this class for correct dimensionality and consistent values.

Returns true if everything is fine otherwise returns false.

Reimplemented from casa::TwoSidedShape.

DiskShape& casa::DiskShape::operator= ( const DiskShape & other )

The assignment operator uses copy semantics.

virtual casacore::Double casa::DiskShape::positionAngleInRad ( ) const

virtual

Implements casa::TwoSidedShape.

virtual casacore::Double casa::DiskShape::sample	(	const casacore::MDirection &	direction,
		const casacore::MVAngle &	pixelLatSize,
		const casacore::MVAngle &	pixelLongSize
	)		const

virtual

Calculate the proportion of the flux that is in a pixel of specified size centered in the specified direction.

The returned value will always be between zero and one (inclusive).

Implements casa::TwoSidedShape.

virtual void casa::DiskShape::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

virtual

Same as the previous function except that many directions can be sampled at once.

The reference frame and pixel size must be the same for all the specified directions.

Implements casa::TwoSidedShape.

virtual void casa::DiskShape::setWidthInRad	(	const casacore::Double	majorAxis,
		const casacore::Double	minorAxis,
		const casacore::Double	positionAngle
	)

virtual

set or return the width and orientation of the disk.

All numerical values are in radians. There are also functions in the base class for doing this with other angular units.

Implements casa::TwoSidedShape.

virtual casacore::String casa::DiskShape::sizeToString ( ) const

virtual

Get the string containing the various size quantities of a component.

Implements casa::TwoSidedShape.

virtual ComponentType::Shape casa::DiskShape::type ( ) const

virtual

get the type of the shape.

This function always returns ComponentType::DISK.

Implements casa::TwoSidedShape.

virtual casacore::DComplex casa::DiskShape::visibility	(	const casacore::Vector< casacore::Double > &	uvw,
		const casacore::Double &	frequency
	)		const

virtual

Return the Fourier transform of the component at the specified point in the spatial frequency domain.

The point is specified by a 3 element vector (u,v,w) that has units of meters and the frequency of the observation, in Hertz. These two quantities can be used to derive the required spatial frequency (s = uvw*freq/c). The w component is not used in these functions.

The reference position for the transform is the direction of the component. As this component is symmetric about this point the transform is always a real value.

Implements casa::TwoSidedShape.

virtual void casa::DiskShape::visibility	(	casacore::Vector< casacore::DComplex > &	scale,
		const casacore::Matrix< casacore::Double > &	uvw,
		const casacore::Double &	frequency
	)		const

virtual

Same as the previous function except that many (u,v,w) points can be sampled at once.

The uvw casacore::Matrix must have a first dimension of three, and a second dimension that is the same as the length of the scale Vector. Otherwise and exception is thrown (when compiled in debug mode).

Implements casa::TwoSidedShape.

virtual void casa::DiskShape::visibility	(	casacore::Matrix< casacore::DComplex > &	scale,
		const casacore::Matrix< casacore::Double > &	uvw,
		const casacore::Vector< casacore::Double > &	frequency
	)		const

virtual

same as above except with many frequencies

Implements casa::TwoSidedShape.

Member Data Documentation

casacore::Double casa::DiskShape::_majorAxis

private

The parameters of the disk.

Definition at line 290 of file DiskShape.h.

casacore::Double casa::DiskShape::_minorAxis

private

Definition at line 291 of file DiskShape.h.

casacore::Double casa::DiskShape::_pa

private

Definition at line 292 of file DiskShape.h.

casacore::Double casa::DiskShape::_recipArea

private

Definition at line 293 of file DiskShape.h.

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

casa/code/components/ComponentModels/DiskShape.h

Public Member Functions

Private Member Functions

Static Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Intended use:

Review Status

Prerequisite

Synopsis

Example

To Do

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation