- E
- T
- F
- D
- COMPOSITE
- POWEROF2
- ANY
A SkyJones implements the instrumental effect of some sky-plane based calibration effect. It conceptually applies an image of Jones matrices to an image. For example, it takes an image of the sky brightness and applies the complex primary beam for a given interferometer. Only the interface is defined here in the Abstract Base Class. Actual concrete classes must be derived from SkyJones. Some (most) SkyJones are solvable: the SkyEquation can be used by the SkyJones to return gradients with respect to itself (via the image interface). Thus for a SkyJones to solve for itself, it calls the SkyEquation methods to get gradients of chi-squared with respect to the image pixel values. The SkyJones then uses these gradients as appropriate to update itself.
The following examples illustrate how a SkyJones can be used:
// Low level code example:
MeasurementSet ms("imagertest/3C273XC1.ms", Table::Update);
VPSkyJones unsquintedVPSJ(ms);
VPSkyJones squintedVPSJ(ms, True, Quantity(5.0, "deg"), BeamSquint::GOFIGURE);
unsquintedVPSJ.reset();
squintedVPSJ.reset();
PagedImage<Complex> imageIn;
PagedImage<Complex> imageOut; // in reality, this ouwld need more construction with coords and shapes
VisSet vs(ms,bi,chanSelection,interval);
Int row = 0;
VisIter &vi = vs.iter();
VisBuffer vb(vi);
for (vi.originChunks();vi.moreChunks();vi.nextChunk()) {
cout << "This is integration: " << nChunks++ << endl;
for (vi.origin();vi.more();vi++) {
if (myVPSJ.change(vb)) {
cout << "State has changed: " << endl;
squintedVPSJ.showState(os);
squintedVPSJ.apply(imageIn, imageOut, vb, row);
}
}
}
// High Level Code Example:
// Create an ImageSkyJones from an image on disk
ImageSkyModel ism(PagedImage<Float>("3C273XC1.modelImage"));
// Make an FTMachine: here we use a simple Grid and FT.
GridFT ft;
SkyEquation se(ism, vs, ft);
// Make a Primary Beam Sky Model
VPSkyJones pbsj(ms);
// Add it to the SkyEquation
se.setSkyJones(pbsj);
// Predict the visibility set
se.predict();
// Read some other data
VisSet othervs("3c84.MS.Otherdata");
// Make a Clean Image and write it out
HogbomCleanImageSkyJones csm(ism);
if (csm.solve(othervs)) {
PagedImage<Float> cleanImage=csm.image(0);
cleanImage.setName("3c84.cleanImage");
}
Apply Jones matrix to an image (and adjoint)
Apply Jones matrix to a sky component (and adjoint)
Has this operator changed since the last application?
Does this operator changed in this VisBuffer, starting with row1? If yes, we return in row2, the last row that has the same SkyJones as row1.
Reset
Assure
Does the operator change in this visbuffer or since the last call? I'm not sure this is useful -- come back to it m.a.h. Dec 30 1999
Return the type of this Jones matrix (actual type of derived class).
Apply gradient
Is this solveable?
Initialize for gradient search
Finalize for gradient search
Add to Gradient Chisq
Solve
Get the ImageRegion of the primary beam on an Image for a given pointing Note: ImageRegion is not necesarily constrained to lie within the image region (for example, if the pointing center is near the edge of the image). fPad: extra fractional padding beyond the primary beam support (note: we do not properly treat squint yet, this will cover it for now) iChan: frequency channel to take: lowest frequency channel is safe for all SizeType: COMPOSITE = next larger composite number, POWEROF2 = next larger power of 2, ANY = just take what we get!
Potential problem: this ImageRegion includes all Stokes and Frequency Channels present in the input image.