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casa
$Rev:20696$
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casa
$Rev:20696$
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A Class for performing Hogbom Clean's of Arrays. More...
#include <HogbomCleanModel.h>
Public Member Functions | |
| HogbomCleanModel () | |
| The default constructor does nothing more than initialise a zero length array to hold the deconvolved model. | |
| HogbomCleanModel (const Array< T > &model) | |
| Construct the HogbomCleanModel object and initialise the model. | |
| Bool | solve (ResidualEquation< Array< T > > &eqn) |
| Using a Hogbom clean deconvolution proceedure solve for an improved estimate of the deconvolved object. | |
| Bool | solve (ConvolutionEquation &eqn) |
A Class for performing Hogbom Clean's of Arrays.
Public interface
This class is called HogbomCleanModel because thats the algorithm it uses deconvolve the model.
This class is used to perform the Hogbom Clean Algorithm on an Array. Only the deconvolved model of the sky are directly stored by this class. The point spread function (psf) and convolved (dirty) image are stored in a companion class which is must be derived from ResidualEquation.
The cleaning works like this. The user constructs a HogbomCleanModel by specifying an initial model of the sky. This can by be one,two,three... dimensional depending on the dimension of the psf (see below). The user then constructs a class which implements the forward equation between the model and the dirty image. Typically this will be the ConvolutionEquation class, although any class which has a ResidualEquation interface will be work (but perhaps very slowly, as the ConvolutionEquation class has member functions optimised for cleaning)
The user then calls the solve() function (with the appropriate equation class as an arguement), and this class will perform the Hogbom clean. The various clean parameters are set (prior to calling solve) using the functions derived from the Iterate class, in particular setGain(), setNumberIterations() & setThreshold() (to set a flux limit).
The solve() function does not return either the deconvolved model or the residuals. The solved model can be obtained using the getModel() function (derived from ArrayModel()) and the residual can be obtained using the residual() member function of the Convolution/Residual Equation Class.
The size and shape of the model used in this class MUST be the same as the convolved data (Dirty Image), stored in the companion ResidualEquation Class. However the model (and convolved data) can have more dimensions than the psf, as well as a different size (either larger or smaller). When the dimensionality is different the cleaning is done independendtly in each "plane" of the model. (Note this has not been implemented yet but is relatively simple to do if necessary).
This multi-dimensionalty is exploited when cleaning arrays of StokesVectors. Here the Array of StokesVectors is decomposed into a stack of 4 Floating point arrays and the cleaning is done on all the the arrays simultaneosly. The criterion for choosing the brightest pixel has been generalised by using the "length" of the Stokesvector in 4 dimensional space.
A companion class to this one is MaskedHogbomCleanModel. This provides the same functionality but is used with MaskedArrays which indicate which regions of the model to search for clean components.
Matrix<Float> psf(12,12), dirty(10,10), initialModel(10,10);
...put appropriate values into psf, dirty, & initialModel...\.
HogbomCleanModel<Float> deconvolvedModel(initialModel);
ConvolutionEquation convEqn(psf, dirty);
deconvolvedModel.setGain(0.2);
deconvolvedModel.setNumberIterations(1000);
Bool convWorked = deconvolvedModel.solve(convEqn);
Array<Float> finalModel, residuals;
if (convWorked){
finalModel = deconvolvedModel.getModel();
ConvEqn.residual(deconvolvedModel, finalResidual);
}
This class is needed to deconvolve images.
have tested this class with Arrays of Float StokesVector
Definition at line 141 of file HogbomCleanModel.h.
| casa::HogbomCleanModel< T >::HogbomCleanModel | ( | ) | [inline] |
The default constructor does nothing more than initialise a zero length array to hold the deconvolved model.
If this constructor is used then the actual model must be set using the setModel() function of the ArrayModel class.
Definition at line 150 of file HogbomCleanModel.h.
| casa::HogbomCleanModel< T >::HogbomCleanModel | ( | const Array< T > & | model | ) | [inline] |
Construct the HogbomCleanModel object and initialise the model.
Definition at line 152 of file HogbomCleanModel.h.
| Bool casa::HogbomCleanModel< T >::solve | ( | ResidualEquation< Array< T > > & | eqn | ) |
Using a Hogbom clean deconvolution proceedure solve for an improved estimate of the deconvolved object.
The convolution/residual equation contains the psf and dirty image. When called with a ResidualEquation arguement a quite general interface is used that is slow. The convolution equation contains functions that speed things up. The functions return False if the deconvolution could not be done.
| Bool casa::HogbomCleanModel< T >::solve | ( | ConvolutionEquation & | eqn | ) |
1.8.0