org.deegree.crs.projections
Class Projection

java.lang.Object
  org.deegree.crs.Identifiable
      org.deegree.crs.projections.Projection

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

AzimuthalProjection, ConicProjection, CylindricalProjection

public abstract class Projection
extends Identifiable
implements Serializable

Map conversion is the process of changing the map grid coordinates (usually, but not always, Easting & Northing) of a Projected Coordinate Reference System to its corresponding geographical coordinates (Latitude & Longitude) or vice versa.

A projection is conformal if an infinitesimal small perfect circle on the earth's surface results in an infinitesimal small projected perfect circle (an ellipsoid with no eccentricity). In other words, the relative local angles about every point on the map are shown correctly.

An equal area projection can be best explained with a coin (Snyder), a coin (of any size) covers exactly the same area of the actual earth as the same coin on any other part of the map. This can only be done by distorting shape, scale and and angles of the original earth's layout.

Version:

$Revision: 18222 $, $Date: 2009-06-22 14:42:54 +0200 (Mo, 22. Jun 2009) $

Author:

Rutger Bezema, last edited by: $Author: rbezema $

See Also:

Serialized Form

Constructor Summary

Projection(GeographicCRS geographicCRS, double falseNorthing, double falseEasting, javax.vecmath.Point2d naturalOrigin, Unit units, double scale, boolean conformal, boolean equalArea, Identifiable id)
Creates a Projection.

Method Summary

abstract javax.vecmath.Point2d	doInverseProjection(double x, double y) Do an inverse projection from projected (map) coordinates to geographic coordinates.
abstract javax.vecmath.Point2d	doProjection(double lambda, double phi) The actual transform method doing a projection from geographic coordinates to map coordinates.
boolean	equals(Object other)
double	getCosphi0()
Datum	getDatum()
double	getEccentricity()
Ellipsoid	getEllipsoid()
double	getFalseEasting()
double	getFalseNorthing()
GeographicCRS	getGeographicCRS()
abstract String	getImplementationName()
javax.vecmath.Point2d	getNaturalOrigin()
PrimeMeridian	getPrimeMeridian()
double	getProjectionLatitude()
double	getProjectionLongitude()
double	getScale()
double	getScaleFactor()
double	getSemiMajorAxis()
double	getSemiMinorAxis()
double	getSinphi0()
double	getSquaredEccentricity()
Unit	getUnits()
int	hashCode() Implementation as proposed by Joshua Block in Effective Java (Addison-Wesley 2001), which supplies an even distribution and is relatively fast.
boolean	isConformal()
boolean	isEqualArea()
boolean	isSpherical()
void	setFalseEasting(double newFalseEasting) sets the false easting to given value.
void	setScale(double scale) Sets the old scale to the given scale, also adjusts the scaleFactor.
String	toString()

Methods inherited from class org.deegree.crs.Identifiable

checkForNullObject, checkForNullObject, checkForNullObject, getAreaOfUse, getAreaOfUseBBox, getAreasOfUse, getDescription, getDescriptions, getIdAndName, getIdentifier, getIdentifiers, getName, getNames, getVersion, getVersions, hasID

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Projection

public Projection(GeographicCRS geographicCRS,
                  double falseNorthing,
                  double falseEasting,
                  javax.vecmath.Point2d naturalOrigin,
                  Unit units,
                  double scale,
                  boolean conformal,
                  boolean equalArea,
                  Identifiable id)

Creates a Projection. Caution, the given natural origin should be given in radians rather then degrees.

Parameters:

geographicCRS - which this projection uses.

falseNorthing - in given units

falseEasting - in given units

naturalOrigin - in radians longitude, latitude.

units - of the map projection

scale - at the prime meridian (e.g. 0.9996 for UTM)

conformal - if the projection is conformal

equalArea - if the projection result in an equal area map

id - an identifiable instance containing information about this projection.

Method Detail

doProjection

public abstract javax.vecmath.Point2d doProjection(double lambda,
                                                   double phi)
                                            throws ProjectionException

The actual transform method doing a projection from geographic coordinates to map coordinates.

Parameters:

lambda - the longitude

phi - the latitude

Returns:

the projected Point or Point(Double.NAN, Double.NAN) if an error occurred.

Throws:

ProjectionException - if the given lamba and phi coordinates could not be projected to x and y.

doInverseProjection

public abstract javax.vecmath.Point2d doInverseProjection(double x,
                                                          double y)
                                                   throws ProjectionException

Do an inverse projection from projected (map) coordinates to geographic coordinates.

Parameters:

x - coordinate on the map

y - coordinate on the map

Returns:

the projected Point with x = lambda and y = phi;

Throws:

ProjectionException - if the given x and y coordinates could not be inverted to lambda and phi.

getImplementationName

public abstract String getImplementationName()

Returns:

A deegree specific name which will be used for the export of a projection.

isConformal

public final boolean isConformal()

Returns:

true if the projection projects conformal.

isEqualArea

public final boolean isEqualArea()

Returns:

true if the projection is projects equal Area.

getScale

public final double getScale()

Returns:

the scale.

setScale

public void setScale(double scale)

Sets the old scale to the given scale, also adjusts the scaleFactor.

Parameters:

scale - the new scale

getScaleFactor

public final double getScaleFactor()

Returns:

the scale*semimajor-axis, often revered to as R*k_0 in Snyder.

getDatum

public final Datum getDatum()

Returns:

the datum.

getFalseEasting

public final double getFalseEasting()

Returns:

the falseEasting.

setFalseEasting

public void setFalseEasting(double newFalseEasting)

sets the false easting to given value. (Used in for example transverse mercator, while setting the utm zone).

Parameters:

newFalseEasting - the new false easting parameter.

getFalseNorthing

public final double getFalseNorthing()

Returns:

the falseNorthing.

getNaturalOrigin

public final javax.vecmath.Point2d getNaturalOrigin()

Returns:

the naturalOrigin.

getUnits

public final Unit getUnits()

Returns:

the units.

getPrimeMeridian

public final PrimeMeridian getPrimeMeridian()

Returns:

the primeMeridian of the datum.

getEllipsoid

public final Ellipsoid getEllipsoid()

Returns:

the ellipsoid of the datum.

getEccentricity

public final double getEccentricity()

Returns:

the eccentricity of the ellipsoid of the datum.

getSquaredEccentricity

public final double getSquaredEccentricity()

Returns:

the eccentricity of the ellipsoid of the datum.

getSemiMajorAxis

public final double getSemiMajorAxis()

Returns:

the semiMajorAxis (a) of the ellipsoid of the datum.

getSemiMinorAxis

public final double getSemiMinorAxis()

Returns:

the semiMinorAxis (a) of the ellipsoid of the datum.

isSpherical

public final boolean isSpherical()

Returns:

true if the ellipsoid of the datum is a sphere and not an ellipse.

getProjectionLatitude

public final double getProjectionLatitude()

Returns:

the projectionLatitude also known as central-latitude or latitude-of-origin, in Snyder referenced as phi_1 for azimuthal, phi_0 for other projections.

getProjectionLongitude

public final double getProjectionLongitude()

Returns:

the projectionLongitude also known as projection-meridian or central-meridian, in Snyder referenced as lambda_0

getSinphi0

public final double getSinphi0()

Returns:

the sinphi0, the sine of the projection latitude

getCosphi0

public final double getCosphi0()

Returns:

the cosphi0, the cosine of the projection latitude

getGeographicCRS

public final GeographicCRS getGeographicCRS()

Returns:

the geographicCRS.

equals

public boolean equals(Object other)

Overrides:

equals in class Identifiable

toString

public String toString()

Overrides:

toString in class Identifiable

hashCode

public int hashCode()

Implementation as proposed by Joshua Block in Effective Java (Addison-Wesley 2001), which supplies an even distribution and is relatively fast. It is created from field f as follows:

• boolean -- code = (f ? 0 : 1)
• byte, char, short, int -- code = (int)f
• long -- code = (int)(f ^ (f >>>32))
• float -- code = Float.floatToIntBits(f);
• double -- long l = Double.doubleToLongBits(f); code = (int)(l ^ (l >>> 32))
• all Objects, (where equals( ) calls equals( ) for this field) -- code = f.hashCode( )
• Array -- Apply above rules to each element

Combining the hash code(s) computed above: result = 37 * result + code;

Overrides:

hashCode in class Object

Returns:

(int) ( result >>> 32 ) ^ (int) result;

See Also:

Object.hashCode()