skyview.geometry

Class Projection

java.lang.Object

skyview.geometry.Projection

public class Projection
extends java.lang.Object

This class implements projection algorithms to/from a projection plane and the unit sphere. Data on the unit sphere is normally represented as a unit-three vector. Data in a projection plane is normally represented as a two-ple. Note that the projection is usually broken into two pieces: a transformation to a convenient location on the celestial sphere (e.g., for a TAN projection, the unit vectors are rotated so that the reference pixel is at the pole), and a functional transformation from the sphere to the plane. The project and deproject functions address this later element, while the rotation needed is encoded in in the eulerRotationMatrix.

Constructor Summary

Constructors

Constructor and Description
Projection(java.lang.String type) Get the correct projection
Projection(java.lang.String type, double[] reference) Create the specified projection.

Method Summary

Modifier and Type	Method and Description
static double[]	fixedPoint(java.lang.String proj) This static method returns the location of the default projection center for fixed point projections.
Distorter	getDistorter() Get any distortion in the plane associated with this projection.
Projecter	getProjecter() Get the projection algorithm associated with this rotation.
double[]	getReferencePoint() Get the current reference position
Rotater	getRotater() Get the rotation that needs to be performed before the rotation.
boolean	isFixedProjection() Is this a fixed point projection?
void	setDistorter(Distorter dist)
void	setReference(double lon, double lat)
void	setRotater(Rotater rot) Update the Rotater...
protected double[]	specialReference()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Projection

public Projection(java.lang.String type)
           throws TransformationException

Get the correct projection

Throws:

TransformationException

Projection

public Projection(java.lang.String type,
                  double[] reference)
           throws TransformationException

Create the specified projection.

Parameters:

type - The three character string defining the projection.

reference - The reference point for the projection (as a coordinate pair)

Throws:

TransformationException - when the requested projection cannot be found or does not have an appropriate constructor.

Method Detail

setReference

public void setReference(double lon,
                         double lat)

fixedPoint

public static double[] fixedPoint(java.lang.String proj)

This static method returns the location of the default projection center for fixed point projections. It returns a null if the projection is not normally used as a fixed point projection where the projection is expanded around some fixed point on the sphere regardless of the location of the image data.

Parameters:

proj - The three letter string denoting the projection.

Returns:

The fixed point for the projection or null if not a fixed point projection.

getRotater

public Rotater getRotater()

Get the rotation that needs to be performed before the rotation.

setRotater

public void setRotater(Rotater rot)

Update the Rotater...

getProjecter

public Projecter getProjecter()

Get the projection algorithm associated with this rotation.

getDistorter

public Distorter getDistorter()

Get any distortion in the plane associated with this projection.

setDistorter

public void setDistorter(Distorter dist)

specialReference

protected double[] specialReference()

isFixedProjection

public boolean isFixedProjection()

Is this a fixed point projection?

getReferencePoint

public double[] getReferencePoint()

Get the current reference position