Class AlbersEqualArea

All Implemented Interfaces:
Serializable, Parameterized, LenientComparable, org.opengis.referencing.operation.MathTransform, org.opengis.referencing.operation.MathTransform2D
Direct Known Subclasses:
AlbersEqualArea.Spherical

public class AlbersEqualArea extends AuthalicConversion
Albers Equal Area projection (EPSG code 9822). See the following references for an overview:

The "standard_parallel_2" parameter is optional and will be given the same value as "standard_parallel_1" if not set.

Since:
0.8
Version:
1.3
See Also:
  • Field Details

    • serialVersionUID

      private static final long serialVersionUID
      For cross-version compatibility.
      See Also:
    • nm

      final double nm
      Internal coefficients for computation, depending only on eccentricity and values of standards parallels. This is defined as n = (m₁² – m₂²) / (α₂ – α₁) in §1.3.13 of IOGP Publication 373-7-2 (april 2015).

      In Apache SIS implementation, we use modified formulas in which the (1 - ℯ²) factor is omitted in AuthalicConversion.qm(double) calculation. Consequently, what we get is a modified value nm which is related to Snyder's n value by n = nm / (1 - ℯ²). The omitted (1 - ℯ²) factor is either taken in account by the (de)normalization matrix, or cancels with other (1 - ℯ²) factors when we develop the formulas.

      Note that in the spherical case, nm = Snyder's n.

    • C

      final double C
      Internal coefficients for computation, depending only on values of standards parallels. This is defined as C = m₁² + (n⋅α₁) in §1.3.13 of IOGP Publication 373-7-2 – Geomatics Guidance Note number 7, part 2 – April 2015.
  • Constructor Details

    • AlbersEqualArea

      public AlbersEqualArea(org.opengis.referencing.operation.OperationMethod method, Parameters parameters)
      Creates an Albers Equal Area projection from the given parameters.
      Parameters:
      method - description of the projection parameters.
      parameters - the parameter values of the projection to create.
    • AlbersEqualArea

      @Workaround(library="JDK", version="1.7") private AlbersEqualArea(Initializer initializer)
      Work around for RFE #4093999 in Sun's bug database ("Relax constraint on placement of this()/super() call in constructors").
    • AlbersEqualArea

      AlbersEqualArea(AlbersEqualArea other)
      Creates a new projection initialized to the same parameters than the given one.
  • Method Details

    • initializer

      @Workaround(library="JDK", version="1.7") private static Initializer initializer(org.opengis.referencing.operation.OperationMethod method, Parameters parameters)
      Work around for RFE #4093999 in Sun's bug database ("Relax constraint on placement of this()/super() call in constructors").
    • getInternalParameterNames

      final String[] getInternalParameterNames()
      Returns the names of additional internal parameters which need to be taken in account when comparing two AlbersEqualArea projections or formatting them in debug mode.
      Overrides:
      getInternalParameterNames in class NormalizedProjection
    • getInternalParameterValues

      final double[] getInternalParameterValues()
      Returns the values of additional internal parameters which need to be taken in account when comparing two AlbersEqualArea projections or formatting them in debug mode.
      Overrides:
      getInternalParameterValues in class NormalizedProjection
    • createMapProjection

      public org.opengis.referencing.operation.MathTransform createMapProjection(org.opengis.referencing.operation.MathTransformFactory factory) throws org.opengis.util.FactoryException
      Returns the sequence of normalizationthisdenormalization transforms as a whole. The transform returned by this method expects (longitude, latitude) coordinates in degrees and returns (x,y) coordinates in metres.

      The non-linear part of the returned transform will be this transform, except if the ellipsoid is spherical. In the latter case, this transform may be replaced by a simplified implementation.

      Overrides:
      createMapProjection in class NormalizedProjection
      Parameters:
      factory - The factory to use for creating the transform.
      Returns:
      the map projection from (λ,φ) to (x,y) coordinates.
      Throws:
      org.opengis.util.FactoryException - if an error occurred while creating a transform.
      See Also:
    • transform

      public org.opengis.referencing.operation.Matrix transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, boolean derivate) throws ProjectionException
      Projects the specified (θ,φ) coordinates and stores the result in dstPts. In addition, opportunistically computes the projection derivative if derivate is true. The units of measurement are implementation-specific (see super-class javadoc). The results must be multiplied by the denormalization matrix before to get linear distances.
      Specified by:
      transform in class NormalizedProjection
      Parameters:
      srcPts - the array containing the source point coordinates, as (longitude, latitude) angles in radians.
      srcOff - the offset of the single coordinate tuple to be converted in the source array.
      dstPts - the array into which the converted coordinates is returned (may be the same than srcPts). Coordinates will be expressed in a dimensionless unit, as a linear distance on a unit sphere or ellipse.
      dstOff - the offset of the location of the converted coordinates that is stored in the destination array.
      derivate - true for computing the derivative, or false if not needed.
      Returns:
      the matrix of the projection derivative at the given source position, or null if the derivate argument is false.
      Throws:
      ProjectionException - if the coordinates cannot be converted.
      See Also:
    • inverseTransform

      protected void inverseTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff) throws ProjectionException
      Converts the specified (x,y) coordinates and stores the (θ,φ) result in dstPts.
      Specified by:
      inverseTransform in class NormalizedProjection
      Parameters:
      srcPts - the array containing the source point coordinates, 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 coordinates is returned (may be the same than srcPts). Coordinates 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 cannot be converted.