org.geotools.referencing.operation.projection
Class AlbersEqualArea

Object
  extended by Formattable
      extended by AbstractMathTransform
          extended by MapProjection
              extended by AlbersEqualArea
All Implemented Interfaces:
Serializable, MathTransform, MathTransform2D

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:

Since:
2.1
Author:
Gerald I. Evenden (for original code in Proj4), Rueben Schulz
See Also:
Albers Equal-Area Conic Projection on MathWorld, "Albers_Conic_Equal_Area" on RemoteSensing.org, British Columbia Albers Standard Projection, Serialized Form

Nested Class Summary
static class AlbersEqualArea.Provider
          The math transform provider for an Albers Equal Area projection (EPSG code 9822).
 
Nested classes/interfaces inherited from class MapProjection
MapProjection.AbstractProvider
 
Field Summary
 
Fields inherited from class MapProjection
centralMeridian, en0, en1, en2, en3, en4, excentricity, excentricitySquared, falseEasting, falseNorthing, globalScale, invertible, isSpherical, latitudeOfOrigin, LOGGER, scaleFactor, semiMajor, semiMinor
 
Fields inherited from class Formattable
SINGLE_LINE
 
Constructor Summary
protected AlbersEqualArea(ParameterValueGroup parameters)
          Constructs a new map projection from the supplied parameters.
 
Method Summary
 boolean equals(Object object)
          Compares the specified object with this map projection for equality.
 ParameterDescriptorGroup getParameterDescriptors()
          Returns the parameter descriptors for this map projection.
 ParameterValueGroup getParameterValues()
          Returns the parameter values for this map projection.
 int hashCode()
          Returns a hash value for this projection.
protected  Point2D inverseTransformNormalized(double x, double y, Point2D ptDst)
          Transforms the specified (x,y) coordinates and stores the result in ptDst.
protected  Point2D transformNormalized(double x, double y, Point2D ptDst)
          Transforms the specified (λ,φ) coordinates (units in radians) and stores the result in ptDst (linear distance on a unit sphere).
 
Methods inherited from class MapProjection
checkReciprocal, getSourceDimensions, getTargetDimensions, getToleranceForAssertions, inv_mlfn, inverse, mlfn, orthodromicDistance, resetWarnings, transform, transform, transform
 
Methods inherited from class AbstractMathTransform
createTransformedShape, derivative, derivative, ensureNonNull, formatWKT, getName, isIdentity, needCopy, rollLongitude, transform, transform, transform
 
Methods inherited from class Formattable
cleanupThreadLocals, toString, toWKT, toWKT, toWKT, toWKT
 
Methods inherited from class Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface MathTransform2D
createTransformedShape, derivative
 
Methods inherited from interface MathTransform
derivative, isIdentity, toWKT, transform, transform, transform
 

Constructor Detail

AlbersEqualArea

protected AlbersEqualArea(ParameterValueGroup parameters)
                   throws ParameterNotFoundException
Constructs a new map projection from the supplied parameters.

Parameters:
parameters - The parameter values in standard units.
Throws:
ParameterNotFoundException - if a mandatory parameter is missing.
Method Detail

getParameterDescriptors

public 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
Returns:
The parameter descriptors for this math transform, or null.
See Also:
OperationMethod.getParameters()

getParameterValues

public 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.
See Also:
Operation.getParameterValues()

transformNormalized

protected Point2D transformNormalized(double x,
                                      double y,
                                      Point2D ptDst)
                               throws ProjectionException
Transforms the specified (λ,φ) coordinates (units in radians) and stores the result in ptDst (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 ptSrc, or null. Ordinates will be in a dimensionless unit, as a linear distance on a unit sphere or ellipse.
Returns:
the coordinate point after transforming (lambda, phi) and storing the result in ptDst.
Throws:
ProjectionException - if the point can't be transformed.

inverseTransformNormalized

protected Point2D inverseTransformNormalized(double x,
                                             double y,
                                             Point2D ptDst)
                                      throws ProjectionException
Transforms the specified (x,y) coordinates and stores the result in ptDst.

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 ptSrc, or null. Ordinates will be in radians.
Returns:
the coordinate point after transforming x, y and storing the result in ptDst.
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(Object object)
Compares the specified object with this map projection for equality.

Overrides:
equals in class MapProjection
Parameters:
object - The object to compare with this transform.
Returns:
true if the given object is a transform of the same class and if, given identical source position, the transformed position would be the equals.


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