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# Class FITSWCS.projections.CSCProjection

    java.lang.Object
       |
       +----FITSWCS.Projection
               |
               +----FITSWCS.projections.CSCProjection

public class CSCProjection
extends Projection

This class provides support for the COBE quadrilateralized spherical cube projection (CSC) used by the FITS "World Coordinate System" (WCS) convention.

The FITSWCS package was translated from the WCSLIB C library. This original library was written in support for coordinate systems used by astronomical data stored in FITS format. For more information on these coordinate systems, refer to the paper by Greisen and Calabretta at:

> ftp://fits.cv.nrao.edu/fits/documents/wcs/wcs.all.ps.Z

Nomenclature

In WCSLIB the "forward" direction is from (lng,lat) celestial coordinates to (x,y) coordinates in the plane of projection. This accords with the notion that spherical projections are a projection of the sphere onto a plane, the "reverse" direction is therefore that of deprojection from plane to sphere.

Unfortunately, this is opposite to what is generally understood to be the forward direction for FITS, namely that of transforming pixel coordinates to world coordinates. However, the ordering of function argument lists should make it clear what is intended.

Accuracy

Closure to a precision of at least 1.0-10 degree of longitude and latitude has been verified for typical projection parameters on the 1 degree grid of native longitude and latitude (to within 5 degrees of any latitude where the projection may diverge). Notwithstanding this, absolutely no claim is made for the accuracy or reliability of these routines. They are supplied as is, with no warranty of fitness for any purpose.

COPYRIGHT NOTICE

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 Mass Ave, Cambridge, MA 02139, USA.

Correspondence concerning WCSLIB may be directed to:

         Internet email: mcalabre@atnf.csiro.au
         Postal address: Dr. Mark Calabretta,
                         Australia Telescope National Facility,
                         P.O. Box 76,
                         Epping, NSW, 2121,
                         AUSTRALIA

Correspondence concerning the Java implementation may be directed to Raymond L. Plante (rplante@ncsa.uiuc.edu).

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c00
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c10
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c20
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d1
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gstar
mm
omega1
p00
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tol

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CSCProjection()
  Create an CSCProjection object
CSCProjection(double)
  Create an CSCProjection object
CSCProjection(double, double[])
  Create an CSCProjection object
CSCProjection(double[])
  Create an CSCProjection object

##

fwd(double, double)
  Compute (x,y) coordinates in the plane of projection from native spherical coordinates (phi,theta).
rev(double, double)
  Compute native spherical coordinates (phi,theta) from the (x,y) coordinates in the plane of projection.
setProjParm(double[])
  set the projection parameters (which are not used);
setR0(double)
  set the sphere radius

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gstar

      public final static float gstar

mm

      public final static float mm

gamma

      public final static float gamma

omega1

      public final static float omega1

d0

      public final static float d0

d1

      public final static float d1

c00

      public final static float c00

c10

      public final static float c10

c01

      public final static float c01

c11

      public final static float c11

c20

      public final static float c20

c02

      public final static float c02

tol

      protected float tol

p00

      public final static float p00

p10

      public final static float p10

p20

      public final static float p20

p30

      public final static float p30

p40

      public final static float p40

p50

      public final static float p50

p60

      public final static float p60

p01

      public final static float p01

p11

      public final static float p11

p21

      public final static float p21

p31

      public final static float p31

p41

      public final static float p41

p51

      public final static float p51

p02

      public final static float p02

p12

      public final static float p12

p22

      public final static float p22

p32

      public final static float p32

p42

      public final static float p42

p03

      public final static float p03

p13

      public final static float p13

p23

      public final static float p23

p33

      public final static float p33

p04

      public final static float p04

p14

      public final static float p14

p24

      public final static float p24

p05

      public final static float p05

p15

      public final static float p15

p06

      public final static float p06

##

CSCProjection

      public CSCProjection()

  Create an CSCProjection object

CSCProjection

      public CSCProjection(double r0)

  Create an CSCProjection object
  Parameters:
    r0 - sphere radius

CSCProjection

      public CSCProjection(double r0,
                           double p[])

  Create an CSCProjection object
  Parameters:
    r0 - sphere radius
    p - projection parameters. None are actually used by this projection; this constructor is provided to parallel other subclasses of the Projection class

CSCProjection

      public CSCProjection(double p[])

  Create an CSCProjection object
  Parameters:
    p - projection parameters. None are actually used by this projection; this constructor is provided to parallel other subclasses of the Projection class

##

fwd

      public double[] fwd(double phi,
                          double theta) throws PixelBeyondProjectionException

  Compute (x,y) coordinates in the plane of projection from native spherical coordinates (phi,theta).
  Returns:
    double[] a two-element array containing x,y
  Overrides:
    fwd in class Projection

rev

      public double[] rev(double x,
                          double y) throws PixelBeyondProjectionException

  Compute native spherical coordinates (phi,theta) from the (x,y) coordinates in the plane of projection.
  Returns:
    double[] a two-element array containing phi,theta
  Overrides:
    rev in class Projection

setR0

      public void setR0(double r0)

  set the sphere radius
  Overrides:
    setR0 in class Projection

setProjParm

      public void setProjParm(double p[])

  set the projection parameters (which are not used);
  Parameters:
    p - array of projection parameters; if p is null, no update is to be made.
  Overrides:
    setProjParm in class Projection

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