org.geotoolkit.referencing.operation.projection
Class AlbersEqualArea

Object
  FormattableObject
      AbstractMathTransform
          AbstractMathTransform2D
              UnitaryProjection
                  AlbersEqualArea

All Implemented Interfaces:

Serializable, Formattable, Parameterized, LenientComparable, MathTransform, MathTransform2D

@Immutable
public class AlbersEqualArea
extends UnitaryProjection

Albers Equal Area Projection (EPSG code 9822). See the Albers Equal-Area Conic projection on MathWorld for an overview. See any of the following providers for a list of programmatic parameters:

• AlbersEqualArea

Description
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. Meridians 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).

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:

3.18

Author:

Gerald Evenden (USGS), Rueben Schulz (UBC), Martin Desruisseaux (Geomatys), Rémi Maréchal (Geomatys)

See Also:

British Columbia Albers Standard Projection, Serialized Form

Module:

referencing/geotk-referencing (download)

View source code for this class

Nested Class Summary

Nested classes/interfaces inherited from class UnitaryProjection

UnitaryProjection.Parameters

Field Summary

Fields inherited from class UnitaryProjection

excentricity, excentricitySquared

Fields inherited from class FormattableObject

EPSG, GEOTIFF, INTERNAL, OGC, SINGLE_LINE

Constructor Summary

protected

AlbersEqualArea(UnitaryProjection.Parameters parameters) Constructs a new map projection from the supplied parameters.

Method Summary

static MathTransform2D	create(ParameterDescriptorGroup descriptor, ParameterValueGroup values) Creates a Albers Equal Area projection from the given parameters.
Matrix	derivative(Point2D point) Gets the derivative of this transform at a point.
boolean	equals(Object object, ComparisonMode mode) Compares the given object with this transform for equivalence.
ParameterDescriptorGroup	getParameterDescriptors() Returns the parameter descriptors for this unitary projection.
ParameterValueGroup	getParameterValues() Returns a copy of the parameter values for this projection.
protected void	inverseTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff) Transforms the specified (x,y) coordinates and stores the result in dstPts (angles in radians).
protected void	transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff) Transforms the specified (λ,φ) coordinates (units in radians) and stores the result in dstPts (linear distance on a unit sphere).

Methods inherited from class UnitaryProjection

computeHashCode, finish, getUnmarshalledParameters, inverse, resetWarnings, rollLongitude, transform, unrollLongitude

Methods inherited from class AbstractMathTransform2D

getSourceDimensions, getTargetDimensions, transform

Methods inherited from class AbstractMathTransform

createTransformedShape, derivative, ensureNonNull, equals, formatWKT, getName, hashCode, isIdentity, rollLongitude, transform, transform, transform, transform

Methods inherited from class FormattableObject

getDefaultIndentation, print, setDefaultIndentation, toString, toWKT, toWKT, toWKT

Methods inherited from class Object

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

Methods inherited from interface MathTransform2D

createTransformedShape

Methods inherited from interface MathTransform

derivative, isIdentity, toWKT, transform, transform, transform, transform

Constructor Detail

AlbersEqualArea

protected AlbersEqualArea(UnitaryProjection.Parameters parameters)

Constructs a new map projection from the supplied parameters.

Parameters:

parameters - The parameters of the projection to be created.

Method Detail

create

public static MathTransform2D create(ParameterDescriptorGroup descriptor,
                                     ParameterValueGroup values)

Creates a Albers Equal Area projection from the given parameters. The descriptor argument is usually AlbersEqualArea.PARAMETERS, but is not restricted to. If a different descriptor is supplied, it is user's responsibility to ensure that it is suitable to an Albers Equal Area projection.

Parameters:

descriptor - Typically AlbersEqualArea.PARAMETERS.

values - The parameter values of the projection to create.

Returns:

The map projection.

Since:

3.00

getParameterDescriptors

public ParameterDescriptorGroup getParameterDescriptors()

Returns the parameter descriptors for this unitary projection. Note that the returned descriptor is about the unitary projection, not the full one.

Specified by:

getParameterDescriptors in interface Parameterized

Overrides:

getParameterDescriptors in class AbstractMathTransform2D

Returns:

The parameter descriptors for this math transform, or null.

See Also:

OperationMethod.getParameters()

getParameterValues

public ParameterValueGroup getParameterValues()

Returns a copy of the parameter values for this projection. The default implementation returns the parameters defined in the super-class, with the addition of standard parallels and the latitude of origin.

Specified by:

getParameterValues in interface Parameterized

Overrides:

getParameterValues in class UnitaryProjection

Returns:

A copy of the parameter values for this unitary projection.

See Also:

SingleOperation.getParameterValues()

transform

protected void transform(double[] srcPts,
                         int srcOff,
                         double[] dstPts,
                         int dstOff)
                  throws ProjectionException

Transforms the specified (λ,φ) coordinates (units in radians) and stores the result in dstPts (linear distance on a unit sphere).

Specified by:

transform in class UnitaryProjection

Parameters:

srcPts - The array containing the source point coordinate, as (longitude, latitude) angles in radians.

srcOff - The offset of the point to be converted in the source array.

dstPts - the array into which the converted point coordinate is returned (may be the same than srcPts). Ordinates will be in a dimensionless unit, as a linear distance on a unit sphere or ellipse.

dstOff - The offset of the location of the converted point that is stored in the destination array.

Throws:

ProjectionException - if the point can't be converted.

inverseTransform

protected void inverseTransform(double[] srcPts,
                                int srcOff,
                                double[] dstPts,
                                int dstOff)
                         throws ProjectionException

Transforms the specified (x,y) coordinates and stores the result in dstPts (angles in radians).

Specified by:

inverseTransform in class UnitaryProjection

Parameters:

srcPts - The array containing the source point coordinate, as linear distance on a unit sphere or ellipse.

srcOff - The offset of the point to be converted in the source array.

dstPts - the array into which the converted point coordinate is returned (may be the same than srcPts). Ordinates will be (longitude, latitude) angles in radians.

dstOff - The offset of the location of the converted point that is stored in the destination array.

Throws:

ProjectionException - if the point can't be converted.

derivative

public Matrix derivative(Point2D point)
                  throws ProjectionException

Gets the derivative of this transform at a point. The current implementation is derived from the ellipsoidal formulas.

Specified by:

derivative in interface MathTransform2D

Overrides:

derivative in class AbstractMathTransform

Parameters:

point - The coordinate point where to evaluate the derivative.

Returns:

The derivative at the specified point as a 2×2 matrix.

Throws:

ProjectionException - if the derivative can't be evaluated at the specified point.

Since:

3.18

See Also:

MathTransform2D.derivative(Point2D)

equals

public boolean equals(Object object,
                      ComparisonMode mode)

Compares the given object with this transform for equivalence.

Specified by:

equals in interface LenientComparable

Overrides:

equals in class UnitaryProjection

Parameters:

object - The object to compare with this unitary projection for equivalence.

mode - The strictness level of the comparison. Default to STRICT.

Returns:

true if the given object is equivalent to this unitary projection.