Source
casacore::MDirection directionMeas(const casacore::MSPointingColumns& mspc, const casacore::Int& index, const casacore::Double& time);
//# SDGrid.h: Definition for SDGrid
//# Copyright (C) 1996,1997,1998,1999,2000,2001,2002,2003
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library is distributed in the hope that it will be useful, but WITHOUT
//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be adressed as follows:
//# Internet email: aips2-request@nrao.edu.
//# Postal address: AIPS++ Project Office
//# National Radio Astronomy Observatory
//# 520 Edgemont Road
//# Charlottesville, VA 22903-2475 USA
//#
//#
//# $Id$
namespace casa { //# NAMESPACE CASA - BEGIN
namespace refim { //# namespace for imaging refactor
// <summary> An FTMachine for Gridding Single Dish data
// </summary>
// <use visibility=export>
// <reviewed reviewer="" date="" tests="" demos="">
// <prerequisite>
// <li> <linkto class=FTMachine>FTMachine</linkto> module
// <li> <linkto class=SkyEquation>SkyEquation</linkto> module
// <li> <linkto class=VisBuffer>VisBuffer</linkto> module
// </prerequisite>
//
// <etymology>
// FTMachine is a Machine for Fourier Transforms. SDGrid does
// Single Dish gridding in a similar way
// </etymology>
//
// <synopsis>
// The <linkto class=SkyEquation>SkyEquation</linkto> needs to be able
// to perform Fourier transforms on visibility data and to grid
// single dish data.
// SDGrid allows efficient Single Dish processing using a
// <linkto class=VisBuffer>VisBuffer</linkto> which encapsulates
// a chunk of visibility (typically all baselines for one time)
// together with all the information needed for processing
// (e.g. direction coordinates).
//
// Gridding and degridding in SDGrid 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 <linkto class=casacore::LatticeCache>LatticeCache</linkto> class. As the (time-sorted)
// visibility data move around slowly in the image plane, patches are
// swapped in and out as necessary. Thus, optimally, one would keep at
// least one patch per scan line of data.
//
// A grid cache is defined on construction. If the gridded image plane is smaller