Sky Model: Model the Sky Brightness for the SkyEquation. More...

#include <SkyModel.h>

Inheritance diagram for casa::SkyModel:

Public Types
enum	PolRep { CIRCULAR, LINEAR }
Public Member Functions
	SkyModel ()
virtual Int	numberOfModels ()=0
	Number of models contained.
virtual Int	numberOfTaylorTerms ()=0
	MFS : Number of taylor terms per model.
virtual Double	getReferenceFrequency ()=0
	MFS : Reference Frequency.
virtual Int	getTaylorIndex (Int index=0)=0
	MFS : Index of Taylor term in array of nmodels x ntaylorterms.
virtual Bool	isSolveable (Int model=0)=0
	Is this SkyModel solveable?
virtual Bool	doFluxScale (Int model=0)=0
	Is there a flux scale image associated with this model?
virtual void	initializeGradients ()=0
	Initialize for gradient search.
virtual void	finalizeGradients ()=0
	Finalize for gradient search.
virtual ComponentList &	componentList ()=0
	Return the component list.
virtual Bool	hasComponentList ()=0
	Return the component list.
virtual ImageInterface< Float > &	image (Int model=0)=0
	Image interface for this model (Stokes representation)
virtual ImageInterface< Float > &	deltaImage (Int model=0)=0
	Increment in the image.
virtual ImageInterface< Complex > &	cImage (Int model=0)=0
	Complex image (needed for e.g.
virtual ImageInterface< Complex > &	XFR (Int model=0, Int numXFR=0)=0
	Complex XFR.
virtual Bool	hasXFR (Int model=0)=0
virtual ImageInterface< Float > &	PSF (Int model=0)=0
	PSF.
virtual ImageInterface< Float > &	gS (Int model=0)=0
	Gradient of chi-squared wrt pixels.
virtual ImageInterface< Float > &	ggS (Int model=0)=0
	Grad Grad chi-squared wrt pixels (diagonal elements only)
virtual ImageInterface< Float > &	fluxScale (Int model=0)=0
	FluxScale image: image * fluxScale => true brightness distribution.
virtual ImageInterface< Float > &	work (Int model=0)=0
	Work image.
virtual void	addStatistics (Float sumwt, Float chisq)=0
	Add to Sum weights, Chi-Squared.
virtual Matrix< Float > &	weight (Int model=0)=0
	Weight per model (channels, polarizations)
virtual Bool	solve (SkyEquation &se)=0
	Solve for this SkyModel.
virtual Bool	isEmpty (Int model=0)=0
	Is this model empty.
virtual Int	getModelIndex (uInt field=0, uInt taylor=0)=0
void	setAlgorithm (const String &alg)
	set Algorithm (e.g clean, mem, nnls)
const String	getAlgorithm ()
	get Algorithm
void	setSubAlgorithm (const String &alg)
	set Sub Algorithm
const String	getSubAlgorithm ()
	get Sub Algorithm
void	setImageRegion (ImageRegion &ir)
	Set the imageregion that will be used for the next XFR generation.
void	unsetImageRegion ()
	use the default shape
void	setImageNormalization (Bool val)

Bool	isImageNormalized ()
Protected Attributes
String	itsAlgorithm
String	itsSubAlgorithm
ImageRegion *	imageRegion_p
	this ImageRegion is used to suggest the shape for the XFR.
Bool	isImageNormalized_p

Detailed Description

Sky Model: Model the Sky Brightness for the SkyEquation.

Intended use:

Public interface

Prerequisite

Matrix module
Vector module
MeasurementComponents module
VisSet module

Etymology

SkyModel describes an interface for Models to be used in the SkyEquation. It is an Abstract Base Class: most methods must be defined in derived classes.

Synopsis

A SkyModel contains a number of separate models. The interface to SkyEquation is via an image per model. SkyEquation uses this image to calculate Fourier transforms, etc. Some (most) SkyModels are solvable: the SkyEquation can be used by the SkyModel to return gradients with respect to itself (via the image interface). Thus for a SkyModel to solve for itself, it calls the SkyEquation methods to get gradients of chi-squared with respect to the image pixel values (thus returning an image: basically a residual image). The SkyModel then uses these gradients as appropriate to update itself.

The following examples illustrate how a SkyModel can be used:

Simple cleaning: one model. The gradient gives the residual image. A special method gives a PSF.
Cleaning with visibility-based subtraction: one model. The gradient can be calculated as needed (using the SkyEquation) to produce the correct residual image.
Wide-field imaging: one model per patch of the sky that is to be imaged.
Non-coplanar baselines imaging: one model per facet of the polyhedron. At the end of processing all facets are combined into one overall image.
Mosaicing: one model per primary beam pointing. Each model is derived (as needed) by cutting out a patch from the full-field mosaic.

Example

         // Read the VisSet from disk
         VisSet vs("3c84.MS");
   
         // Create an ImageSkyModel from an image on disk
         ImageSkyModel ism(PagedImage<Float>("3c84.modelImage"));
   
         // Make an FTMachine: here we use a simple Grid and FT.
         GridFT ft;
   
         SkyEquation se(ism, vs, ft);
   
         // Predict the visibility set
         se.predict();
   
         // Make a Clean Image and write it out
         HogbomCleanImageSkyModel csm(ism);
         if (csm.solve()) {
           PagedImage<Float> cleanImage=csm.image(0);
           cleanImage.setName("3c84.cleanImage");
         }

Motivation

The properties of a model of the sky must be described for the SkyEquation.

To Do

Multiple images in SkyModel
ComponentModel

Definition at line 132 of file SkyModel.h.

Member Enumeration Documentation

enum casa::SkyModel::PolRep

Enumerator:

CIRCULAR
LINEAR

Definition at line 136 of file SkyModel.h.

Constructor & Destructor Documentation

casa::SkyModel::SkyModel ( ) [inline]

Definition at line 141 of file SkyModel.h.

Member Function Documentation

virtual void casa::SkyModel::addStatistics	(	Float	sumwt,
		Float	chisq
	)		`[pure virtual]`

Add to Sum weights, Chi-Squared.

virtual Int casa::SkyModel::getModelIndex	(	uInt	field = `0`,
		uInt	taylor = `0`
	)		`[pure virtual]`

virtual ImageInterface<Complex>& casa::SkyModel::XFR	(	Int	model = `0`,
		Int	numXFR = `0`
	)		`[pure virtual]`

Public Types

Public Member Functions

Protected Attributes