An FTMachine for Gridded Fourier transforms. More...

#include <rGridFT.h>

Inheritance diagram for casa::rGridFT:

Public Member Functions
	rGridFT (Long cachesize, Int tilesize, CountedPtr< VisibilityResamplerBase > &visResampler, String convType="SF", Float padding=1.0, Bool usezero=True, Bool useDoublePrec=False)
	Constructor: cachesize is the size of the cache in words (e.g.
	rGridFT (Long cachesize, Int tilesize, CountedPtr< VisibilityResamplerBase > &visResampler, String convType, MPosition mLocation, Float padding=1.0, Bool usezero=True, Bool useDoublePrec=False)
	rGridFT (Long cachesize, Int tilesize, CountedPtr< VisibilityResamplerBase > &visResampler, String convType, MDirection mTangent, Float padding=1.0, Bool usezero=True, Bool useDoublePrec=False)
	rGridFT (Long cachesize, Int tilesize, CountedPtr< VisibilityResamplerBase > &visResampler, String convType, MPosition mLocation, MDirection mTangent, Float passing=1.0, Bool usezero=True, Bool useDoublePrec=False)
	rGridFT (const RecordInterface &stateRec)
	Construct from a Record containing the rGridFT state.
	rGridFT (const rGridFT &other)
	Copy constructor.
rGridFT &	operator= (const rGridFT &other)
	Assignment operator.
rGridFT *	clone ()
	Clone.
	~rGridFT ()
void	initializeToVis (ImageInterface< Complex > &image, const VisBuffer &vb)
	Initialize transform to Visibility plane using the image as a template.
void	finalizeToVis ()
	Finalize transform to Visibility plane: flushes the image cache and shows statistics if it is being used.
void	initializeToSky (ImageInterface< Complex > &image, Matrix< Float > &weight, const VisBuffer &vb)
	Initialize transform to Sky plane: initializes the image.
void	finalizeToSky ()
	Finalize transform to Sky plane: flushes the image cache and shows statistics if it is being used.
void	get (VisBuffer &vb, Int row=-1)
	Get actual coherence from grid by degridding.
void	put (const VisBuffer &vb, Int row=-1, Bool dopsf=False, FTMachine::Type type=FTMachine::OBSERVED)
	Put coherence to grid by gridding.
void	makeImage (FTMachine::Type type, VisSet &vs, ImageInterface< Complex > &image, Matrix< Float > &weight)
	Make the entire image.
ImageInterface< Complex > &	getImage (Matrix< Float > &, Bool normalize=True)
	Get the final image: do the Fourier transform and grid-correct, then optionally normalize by the summed weights.
virtual void	normalizeImage (Lattice< Complex > &skyImage, const Matrix< Double > &sumOfWts, Lattice< Float > &sensitivityImage, Bool fftNorm)
void	getWeightImage (ImageInterface< Float > &, Matrix< Float > &)
	Get the final weights image.
virtual Bool	toRecord (String &error, RecordInterface &outRec, Bool withImage=False)
	Save and restore the rGridFT to and from a record.
virtual Bool	fromRecord (String &error, const RecordInterface &inRec)
virtual Bool	isFourier ()
	Can this FTMachine be represented by Fourier convolutions?
virtual void	setNoPadding (Bool nopad)
	To make sure no padding is used in certain gridders.
virtual String	name ()
virtual void	setMiscInfo (const Int qualifier)
	set the order of the Taylor term for MFS this is to tell A-Projection to qualify the accumulated avgPB for each Taylor term in the CFCache.
virtual void	ComputeResiduals (VisBuffer &vb, Bool useCorrected)
	Make the VB and VBStore interefaces for the interim re-factoring work.
	rGridFT (Long cachesize, Int tilesize, String convType="SF", Float padding=1.0, Bool usezero=True, Bool useDoublePrec=False)
	Constructor: cachesize is the size of the cache in words (e.g.
	rGridFT (Long cachesize, Int tilesize, String convType, MPosition mLocation, Float padding=1.0, Bool usezero=True, Bool useDoublePrec=False)
	rGridFT (Long cachesize, Int tilesize, String convType, MDirection mTangent, Float padding=1.0, Bool usezero=True, Bool useDoublePrec=False)
	rGridFT (Long cachesize, Int tilesize, String convType, MPosition mLocation, MDirection mTangent, Float passing=1.0, Bool usezero=True, Bool useDoublePrec=False)
	rGridFT (const RecordInterface &stateRec)
	Construct from a Record containing the GridFT state.
	rGridFT (const rGridFT &other)
	Copy constructor.
rGridFT &	operator= (const rGridFT &other)
	Assignment operator.
	~rGridFT ()
void	initializeToVis (ImageInterface< Complex > &image, const VisBuffer &vb)
	Initialize transform to Visibility plane using the image as a template.
void	finalizeToVis ()
	Finalize transform to Visibility plane: flushes the image cache and shows statistics if it is being used.
void	initializeToSky (ImageInterface< Complex > &image, Matrix< Float > &weight, const VisBuffer &vb)
	Initialize transform to Sky plane: initializes the image.
void	finalizeToSky ()
	Finalize transform to Sky plane: flushes the image cache and shows statistics if it is being used.
void	get (VisBuffer &vb, Int row=-1)
	Get actual coherence from grid by degridding.
void	put (const VisBuffer &vb, Int row=-1, Bool dopsf=False, FTMachine::Type type=FTMachine::OBSERVED)
	Put coherence to grid by gridding.
void	makeImage (FTMachine::Type type, VisSet &vs, ImageInterface< Complex > &image, Matrix< Float > &weight)
	Make the entire image.
ImageInterface< Complex > &	getImage (Matrix< Float > &, Bool normalize=True)
	Get the final image: do the Fourier transform and grid-correct, then optionally normalize by the summed weights.
virtual void	normalizeImage (Lattice< Complex > &, const Matrix< Double > &, Lattice< Float > &, Bool)
void	getWeightImage (ImageInterface< Float > &, Matrix< Float > &)
	Get the final weights image.
virtual Bool	toRecord (String &error, RecordInterface &outRec, Bool withImage=False)
	Save and restore the GridFT to and from a record.
virtual Bool	fromRecord (String &error, const RecordInterface &inRec)
virtual Bool	isFourier ()
	Can this FTMachine be represented by Fourier convolutions?
virtual void	setNoPadding (Bool nopad)
	To make sure no padding is used in certain gridders.
virtual String	name () const
	Return the name of the machine.
virtual void	setMiscInfo (const Int qualifier)
	set the order of the Taylor term for MFS this is to tell A-Projection to qualify the accumulated avgPB for each Taylor term in the CFCache.
virtual void	ComputeResiduals (VisBuffer &, Bool)
	Make the VB and VBStore interefaces for the interim re-factoring work.
Protected Member Functions
Array< Complex > *	getDataPointer (const IPosition &, Bool)
	Get the appropriate data pointer.
void	ok ()
void	init ()
Bool	recordOnGrid (const VisBuffer &vb, Int rownr) const
	Is this record on Grid? check both ends.
Array< Complex > *	getDataPointer (const IPosition &, Bool)
	Get the appropriate data pointer.
void	ok ()
void	init ()
void	prepGridForDegrid ()
	Prepare the grid for degridding.
Bool	recordOnGrid (const VisBuffer &vb, Int rownr) const
	Is this record on Grid? check both ends.
Protected Attributes
Float	padding_p
	Padding in FFT.
LatticeCache< Complex > *	imageCache
	Image cache.
Long	cachesize
	Sizes.
Int	tilesize
ConvolveGridder< Double, Complex > *	gridder
	Gridder.
Bool	isTiled
	Is this tiled?
CountedPtr< Lattice< Complex > >	arrayLattice
	Array lattice.
CountedPtr< Lattice< Complex > >	lattice
	Lattice.
String	convType
Float	maxAbsData
IPosition	centerLoc
	Useful IPositions.
IPosition	offsetLoc
Vector< Double >	uvScale
	Image Scaling and offset.
Vector< Double >	uvOffset
Array< Complex >	griddedData
	Array for non-tiled gridding.
Array< DComplex >	griddedData2
Int	priorCacheSize
Bool	usezero_p
	Grid/degrid zero spacing points?
Bool	noPadding_p
	force no padding
Bool	usePut2_p
	Check if using put that avoids non-necessary reads.
String	machineName_p
	machine name
CountedPtr < VisibilityResamplerBase >	visResampler_p
	VisibilityResampler - a.k.a the "gridder" object VisibilityResampler visResampler_p; CountedPtr<MultiThreadedVisibilityResampler> visResampler_p;.
Double	timemass_p
Double	timegrid_p

Detailed Description

An FTMachine for Gridded Fourier transforms.

Intended use:

Public interface

Prerequisite

FTMachine module
SkyEquation module
VisBuffer module

Etymology

FTMachine is a Machine for Fourier Transforms. rGridFT does Grid-based Fourier transforms.

Synopsis

The SkyEquation needs to be able to perform Fourier transforms on visibility data. rGridFT allows efficient Fourier Transform processing using a VisBuffer which encapsulates a chunk of visibility (typically all baselines for one time) together with all the information needed for processing (e.g. UVW coordinates).

Gridding and degridding in rGridFT are performed using a novel sort-less algorithm. In this approach, the gridded plane is divided into small patches, a cache of which is maintained in memory using a general-purpose LatticeCache class. As the (time-sorted) visibility data move around slowly in the Fourier plane, patches are swapped in and out as necessary. Thus, optimally, one would keep at least one patch per baseline.

A grid cache is defined on construction. If the gridded uv plane is smaller than this, it is kept entirely in memory and all gridding and degridding is done entirely in memory. Otherwise a cache of tiles is kept an paged in and out as necessary. Optimally the cache should be big enough to hold all polarizations and frequencies for all baselines. The paging rate will then be small. As the cache size is reduced below this critical value, paging increases. The algorithm will work for only one patch but it will be very slow!

This scheme works well for arrays having a moderate number of antennas since the saving in space goes as the ratio of baselines to image size. For the ATCA, VLBA and WSRT, this ratio is quite favorable. For the VLA, one requires images of greater than about 200 pixels on a side to make it worthwhile.

The FFT step is done plane by plane for images having less than 1024 * 1024 pixels on each plane, and line by line otherwise.

The gridding and degridding steps are implemented in Fortran for speed. In gridding, the visibilities are added onto the grid points in the neighborhood using a weighting function. In degridding, the value is derived by a weight summ of the same points, using the same weighting function.

Example

See the example for SkyModel .

Motivation

Define an interface to allow efficient processing of chunks of visibility data

Intended use:

Public interface

Prerequisite

FTMachine module
SkyEquation module
VisBuffer module

Etymology

FTMachine is a Machine for Fourier Transforms. GridFT does Grid-based Fourier transforms.

Synopsis

The SkyEquation needs to be able to perform Fourier transforms on visibility data. GridFT allows efficient Fourier Transform processing using a VisBuffer which encapsulates a chunk of visibility (typically all baselines for one time) together with all the information needed for processing (e.g. UVW coordinates).

Gridding and degridding in GridFT are performed using a novel sort-less algorithm. In this approach, the gridded plane is divided into small patches, a cache of which is maintained in memory using a general-purpose LatticeCache class. As the (time-sorted) visibility data move around slowly in the Fourier plane, patches are swapped in and out as necessary. Thus, optimally, one would keep at least one patch per baseline.

A grid cache is defined on construction. If the gridded uv plane is smaller than this, it is kept entirely in memory and all gridding and degridding is done entirely in memory. Otherwise a cache of tiles is kept an paged in and out as necessary. Optimally the cache should be big enough to hold all polarizations and frequencies for all baselines. The paging rate will then be small. As the cache size is reduced below this critical value, paging increases. The algorithm will work for only one patch but it will be very slow!

This scheme works well for arrays having a moderate number of antennas since the saving in space goes as the ratio of baselines to image size. For the ATCA, VLBA and WSRT, this ratio is quite favorable. For the VLA, one requires images of greater than about 200 pixels on a side to make it worthwhile.

The FFT step is done plane by plane for images having less than 1024 * 1024 pixels on each plane, and line by line otherwise.

The gridding and degridding steps are implemented in Fortran for speed. In gridding, the visibilities are added onto the grid points in the neighborhood using a weighting function. In degridding, the value is derived by a weight summ of the same points, using the same weighting function.

Example

See the example for SkyModel .

Motivation

Define an interface to allow efficient processing of chunks of visibility data

Definition at line 124 of file rGridFT.h.

Constructor & Destructor Documentation

casa::rGridFT::rGridFT	(	Long	cachesize,
		Int	tilesize,
		CountedPtr< VisibilityResamplerBase > &	visResampler,
		String	convType = `"SF"`,
		Float	padding = `1.0`,
		Bool	usezero = `True`,
		Bool	useDoublePrec = `False`
	)

Constructor: cachesize is the size of the cache in words (e.g.

a few million is a good number), tilesize is the size of the tile used in gridding (cannot be less than 12, 16 works in most cases), and convType is the type of gridding used (SF is prolate spheriodal wavefunction, and BOX is plain box-car summation). mLocation is the position to be used in some phase rotations. If mTangent is specified then the uvw rotation is done for that location iso the image center.

casa::rGridFT::rGridFT	(	Long	cachesize,
		Int	tilesize,
		CountedPtr< VisibilityResamplerBase > &	visResampler,
		String	convType,
		MPosition	mLocation,
		Float	padding = `1.0`,
		Bool	usezero = `True`,
		Bool	useDoublePrec = `False`
	)

casa::rGridFT::rGridFT	(	Long	cachesize,
		Int	tilesize,
		CountedPtr< VisibilityResamplerBase > &	visResampler,
		String	convType,
		MDirection	mTangent,
		Float	padding = `1.0`,
		Bool	usezero = `True`,
		Bool	useDoublePrec = `False`
	)

casa::rGridFT::rGridFT	(	Long	cachesize,
		Int	tilesize,
		CountedPtr< VisibilityResamplerBase > &	visResampler,
		String	convType,
		MPosition	mLocation,
		MDirection	mTangent,
		Float	passing = `1.0`,
		Bool	usezero = `True`,
		Bool	useDoublePrec = `False`
	)

casa::rGridFT::rGridFT ( const RecordInterface & stateRec )

Construct from a Record containing the rGridFT state.

casa::rGridFT::rGridFT ( const rGridFT & other )

Copy constructor.

casa::rGridFT::~rGridFT ( )

casa::rGridFT::rGridFT	(	Long	cachesize,
		Int	tilesize,
		String	convType = `"SF"`,
		Float	padding = `1.0`,
		Bool	usezero = `True`,
		Bool	useDoublePrec = `False`
	)

Constructor: cachesize is the size of the cache in words (e.g.

a few million is a good number), tilesize is the size of the tile used in gridding (cannot be less than 12, 16 works in most cases), and convType is the type of gridding used (SF is prolate spheriodal wavefunction, and BOX is plain box-car summation). mLocation is the position to be used in some phase rotations. If mTangent is specified then the uvw rotation is done for that location iso the image center.

casa::rGridFT::rGridFT	(	Long	cachesize,
		Int	tilesize,
		String	convType,
		MPosition	mLocation,
		Float	padding = `1.0`,
		Bool	usezero = `True`,
		Bool	useDoublePrec = `False`
	)

casa::rGridFT::rGridFT	(	Long	cachesize,
		Int	tilesize,
		String	convType,
		MDirection	mTangent,
		Float	padding = `1.0`,
		Bool	usezero = `True`,
		Bool	useDoublePrec = `False`
	)

casa::rGridFT::rGridFT	(	Long	cachesize,
		Int	tilesize,
		String	convType,
		MPosition	mLocation,
		MDirection	mTangent,
		Float	passing = `1.0`,
		Bool	usezero = `True`,
		Bool	useDoublePrec = `False`
	)

casa::rGridFT::rGridFT ( const RecordInterface & stateRec )

Construct from a Record containing the GridFT state.

casa::rGridFT::rGridFT ( const rGridFT & other )

Copy constructor.

casa::rGridFT::~rGridFT ( )

Member Function Documentation

rGridFT* casa::rGridFT::clone ( )

Clone.

virtual void casa::rGridFT::ComputeResiduals	(	VisBuffer &	vb,
		Bool	useCorrected
	)		`[inline, virtual]`

Make the VB and VBStore interefaces for the interim re-factoring work.

Finally removed the VB interface.

virtual Bool casa::rGridFT::fromRecord	(	String &	error,
		const RecordInterface &	inRec
	)		`[virtual]`

void casa::rGridFT::get	(	VisBuffer &	vb,
		Int	row = `-1`
	)		`[virtual]`

Array<Complex>* casa::rGridFT::getDataPointer	(	const IPosition &	,
		Bool
	)		`[protected]`

ImageInterface<Complex>& casa::rGridFT::getImage	(	Matrix< Float > &	,
		Bool	normalize = `True`
	)		`[virtual]`

void casa::rGridFT::getWeightImage	(	ImageInterface< Float > &	,
		Matrix< Float > &
	)		`[virtual]`

void casa::rGridFT::initializeToSky	(	ImageInterface< Complex > &	image,
		Matrix< Float > &	weight,
		const VisBuffer &	vb
	)		`[virtual]`

void casa::rGridFT::initializeToVis	(	ImageInterface< Complex > &	image,
		const VisBuffer &	vb
	)		`[virtual]`

void casa::rGridFT::makeImage	(	FTMachine::Type	type,
		VisSet &	vs,
		ImageInterface< Complex > &	image,
		Matrix< Float > &	weight
	)		`[virtual]`

virtual void casa::rGridFT::normalizeImage	(	Lattice< Complex > &	,
		const Matrix< Double > &	,
		Lattice< Float > &	,
		Bool
	)		`[inline, virtual]`

virtual void casa::rGridFT::normalizeImage	(	Lattice< Complex > &	skyImage,
		const Matrix< Double > &	sumOfWts,
		Lattice< Float > &	sensitivityImage,
		Bool	fftNorm
	)		`[inline, virtual]`

void casa::rGridFT::put	(	const VisBuffer &	vb,
		Int	row = `-1`,
		Bool	dopsf = `False`,
		FTMachine::Type	type = `FTMachine::OBSERVED`
	)		`[virtual]`

Bool casa::rGridFT::recordOnGrid	(	const VisBuffer &	vb,
		Int	rownr
	)		const `[protected]`

virtual Bool casa::rGridFT::toRecord	(	String &	error,
		RecordInterface &	outRec,
		Bool	withImage = `False`
	)		`[virtual]`

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Intended use:

Prerequisite

Etymology

Synopsis

Example

Motivation

Intended use:

Prerequisite

Etymology

Synopsis

Example

Motivation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation