org.geotools.referencing.operation.projection
Class AlbersEqualArea

java.lang.Object
  org.geotools.referencing.wkt.Formattable
      org.geotools.referencing.operation.transform.AbstractMathTransform
          org.geotools.referencing.operation.projection.MapProjection
              org.geotools.referencing.operation.projection.AlbersEqualArea

All Implemented Interfaces:

org.opengis.referencing.operation.MathTransform, org.opengis.referencing.operation.MathTransform2D, java.io.Serializable

public class AlbersEqualArea

extends MapProjection

Albers Equal Area Projection (EPSG code 9822). This is a conic projection with parallels being unequally spaced arcs of concentric circles, more closely spaced at north and south edges of the map. Merideans are equally spaced radii of the same circles and intersect parallels at right angles. As the name implies, this projection minimizes distortion in areas.

The "standard_parallel_2" parameter is optional and will be given the same value as "standard_parallel_1" if not set (creating a 1 standard parallel projection).

NOTE: formulae used below are from a port, to java, of the 'proj4' package of the USGS survey. USGS work is acknowledged here.

References:

• Proj-4.4.7 available at www.remotesensing.org/proj
  Relevent files are: PJ_aea.c, pj_fwd.c and pj_inv.c
• John P. Snyder (Map Projections - A Working Manual, U.S. Geological Survey Professional Paper 1395, 1987)
• "Coordinate Conversions and Transformations including Formulas", EPSG Guidence Note Number 7, Version 19.

Since:

2.1

Version:

$Id: AlbersEqualArea.java 18048 2006-02-16 02:35:17Z desruisseaux $

Author:

Rueben Schulz

See Also:

Albers Equal-Area Conic Projection on MathWorld, "Albers_Conic_Equal_Area" on www.remotesensing.org, British Columbia Albers Standard Projection, Serialized Form

Nested Class Summary

static class

AlbersEqualArea.Provider The MathTransformProvider for an Albers Equal Area projection.

Nested classes inherited from class org.geotools.referencing.operation.projection.MapProjection

MapProjection.AbstractProvider

Field Summary

Fields inherited from class org.geotools.referencing.operation.projection.MapProjection

centralMeridian, excentricity, excentricitySquared, falseEasting, falseNorthing, globalScale, isSpherical, latitudeOfOrigin, scaleFactor, semiMajor, semiMinor

Constructor Summary

protected

AlbersEqualArea(org.opengis.parameter.ParameterValueGroup parameters) Constructs a new map projection from the supplied parameters.

Method Summary

boolean	equals(java.lang.Object object) Compares the specified object with this map projection for equality.
org.opengis.parameter.ParameterDescriptorGroup	getParameterDescriptors() Returns the parameter descriptors for this map projection. This is used for a providing a default implementation of MapProjection.getParameterValues(), as well as arguments checking.
org.opengis.parameter.ParameterValueGroup	getParameterValues() Returns the parameter values for this map projection.
int	hashCode() Returns a hash value for this projection.
protected java.awt.geom.Point2D	inverseTransformNormalized(double x, double y, java.awt.geom.Point2D ptDst) Transforms the specified (x,y) coordinate and stores the result in .
protected java.awt.geom.Point2D	transformNormalized(double x, double y, java.awt.geom.Point2D ptDst) Transforms the specified (x,y) coordinate (units in radians) and stores the result in (linear distance on a unit sphere).

Methods inherited from class org.geotools.referencing.operation.projection.MapProjection

getSourceDimensions, getTargetDimensions, getToleranceForAssertions, inverse, transform, transform, transform

Methods inherited from class org.geotools.referencing.operation.transform.AbstractMathTransform

createTransformedShape, derivative, derivative, ensureNonNull, formatWKT, getDimSource, getDimTarget, isIdentity, needCopy, rollLongitude, transform

Methods inherited from class org.geotools.referencing.wkt.Formattable

toString, toWKT, toWKT, toWKT

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.opengis.referencing.operation.MathTransform2D

createTransformedShape, derivative

Methods inherited from interface org.opengis.referencing.operation.MathTransform

derivative, isIdentity, toWKT, transform

Constructor Detail

AlbersEqualArea

protected AlbersEqualArea(org.opengis.parameter.ParameterValueGroup parameters)
                   throws org.opengis.parameter.ParameterNotFoundException

Constructs a new map projection from the supplied parameters.

Parameters:

parameters - The parameter values in standard units.

Throws:

org.opengis.parameter.ParameterNotFoundException - if a mandatory parameter is missing.

Method Detail

getParameterDescriptors

public org.opengis.parameter.ParameterDescriptorGroup getParameterDescriptors()

Returns the parameter descriptors for this map projection. This is used for a providing a default implementation of MapProjection.getParameterValues(), as well as arguments checking.

Specified by:

getParameterDescriptors in class MapProjection

getParameterValues

public org.opengis.parameter.ParameterValueGroup getParameterValues()

Returns the parameter values for this map projection.

Overrides:

getParameterValues in class MapProjection

Returns:

A copy of the parameter values for this map projection.

transformNormalized

protected java.awt.geom.Point2D transformNormalized(double x,
                                                    double y,
                                                    java.awt.geom.Point2D ptDst)
                                             throws ProjectionException

Transforms the specified (x,y) coordinate (units in radians) and stores the result in (linear distance on a unit sphere).

Specified by:

transformNormalized in class MapProjection

Parameters:

x - The longitude of the coordinate, in radians.

y - The latitude of the coordinate, in radians.

ptDst - the specified coordinate point that stores the result of transforming , or . Ordinates will be in a dimensionless unit, as a linear distance on a unit sphere or ellipse.

Returns:

the coordinate point after transforming , and storing the result in .

Throws:

ProjectionException - if the point can't be transformed.

inverseTransformNormalized

protected java.awt.geom.Point2D inverseTransformNormalized(double x,
                                                           double y,
                                                           java.awt.geom.Point2D ptDst)
                                                    throws ProjectionException

Transforms the specified (x,y) coordinate and stores the result in .

Specified by:

inverseTransformNormalized in class MapProjection

Parameters:

x - The easting of the coordinate, linear distance on a unit sphere or ellipse.

y - The northing of the coordinate, linear distance on a unit sphere or ellipse.

ptDst - the specified coordinate point that stores the result of transforming , or . Ordinates will be in radians.

Returns:

the coordinate point after transforming , and storing the result in .

Throws:

ProjectionException - if the point can't be transformed.

hashCode

public int hashCode()

Returns a hash value for this projection.

Overrides:

hashCode in class MapProjection

equals

public boolean equals(java.lang.Object object)

Compares the specified object with this map projection for equality.

Overrides:

equals in class MapProjection