Package org.apache.sis.referencing.operation.projection

Class CylindricalEqualArea

java.lang.Object

org.apache.sis.io.wkt.FormattableObject

org.apache.sis.referencing.operation.transform.AbstractMathTransform

org.apache.sis.referencing.operation.transform.AbstractMathTransform2D

org.apache.sis.referencing.operation.projection.NormalizedProjection

org.apache.sis.referencing.operation.projection.AuthalicConversion

org.apache.sis.referencing.operation.projection.CylindricalEqualArea

All Implemented Interfaces:

Serializable, Parameterized, LenientComparable, org.opengis.referencing.operation.MathTransform, org.opengis.referencing.operation.MathTransform2D

Direct Known Subclasses:

CylindricalEqualArea.Spherical

public class CylindricalEqualArea
extends AuthalicConversion

Cylindrical Equal Area projection (EPSG codes 9834, 9835). This is the simplest equal-area projection. This projection has various names depending on its standard parallel:

Non-exhaustive list of variants

Name	Standard parallel
Lambert cylindrical equal-area	0°
Behrmann cylindrical equal-area	30°
Gall orthographic	45°
Balthasart	50°

Description

The parallels and the meridians are straight lines and cross at right angles. The scale is true along standard parallels, but distortion increase greatly at other locations. Distortions are so great that there is little use of this projection for world mapping purposes. However, this projection may be useful for computing areas.

Since:

0.8

Version:

1.2

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static final class	CylindricalEqualArea.Spherical	Provides the transform equations for the spherical case of the Cylindrical Equal Area projection.
private static enum	CylindricalEqualArea.Variant	The variants of the projection based on the name and identifier of the given operation method.

Nested classes/interfaces inherited from class org.apache.sis.referencing.operation.projection.NormalizedProjection

NormalizedProjection.ParameterRole

Field Summary

Fields

Modifier and Type	Field	Description
private static final long	serialVersionUID	For cross-version compatibility.
private final CylindricalEqualArea.Variant	variant	The type of Cylindrical Equal Area projection.

Fields inherited from class org.apache.sis.referencing.operation.projection.AuthalicConversion

isSpherical, qmPolar

Fields inherited from class org.apache.sis.referencing.operation.projection.NormalizedProjection

ANGULAR_TOLERANCE, context, eccentricity, eccentricitySquared, ITERATION_TOLERANCE, LARGE_LONGITUDE_LIMIT, MAXIMUM_ITERATIONS, POLAR_AREA_LIMIT

Fields inherited from class org.apache.sis.referencing.operation.transform.AbstractMathTransform2D

DIMENSION

Constructor Summary

Constructors

Modifier	Constructor	Description
(package private)	CylindricalEqualArea(CylindricalEqualArea other)	Creates a new projection initialized to the same parameters than the given one.
private	CylindricalEqualArea(Initializer initializer)	Work around for RFE #4093999 in Sun's bug database ("Relax constraint on placement of this()/super() call in constructors").
	CylindricalEqualArea(org.opengis.referencing.operation.OperationMethod method, Parameters parameters)	Creates a Cylindrical Equal Area projection from the given parameters.

Method Summary

Modifier and Type	Method	Description
org.opengis.referencing.operation.MathTransform	createMapProjection(org.opengis.referencing.operation.MathTransformFactory factory)	Returns the sequence of normalization → this → denormalization transforms as a whole.
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").
protected void	inverseTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff)	Converts the specified (x,y) coordinates and stores the result in dstPts (angles in radians).
org.opengis.referencing.operation.Matrix	transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, boolean derivate)	Projects the specified (λ,φ) coordinates (units in radians) and stores the result in dstPts.
void	transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)	Converts a list of coordinate tuples.

Methods inherited from class org.apache.sis.referencing.operation.projection.AuthalicConversion

dqm_dφ, qm, sinβ, φ

Methods inherited from class org.apache.sis.referencing.operation.projection.NormalizedProjection

completeWithWraparound, computeHashCode, delegate, equals, getContextualParameters, getInternalParameterNames, getInternalParameterValues, getParameterDescriptors, getParameterValues, getWraparoundLongitude, inverse, tryConcatenate, tryConcatenate, variant

Methods inherited from class org.apache.sis.referencing.operation.transform.AbstractMathTransform2D

createTransformedShape, derivative, getSourceDimensions, getTargetDimensions, transform

Methods inherited from class org.apache.sis.referencing.operation.transform.AbstractMathTransform

derivative, equals, formatTo, getDomain, hashCode, isIdentity, transform, transform, transform, transform

Methods inherited from class org.apache.sis.io.wkt.FormattableObject

print, toString, toString, toWKT

Methods inherited from class java.lang.Object

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

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

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

Field Details

serialVersionUID

private static final long serialVersionUID

For cross-version compatibility.

See Also:

• Constant Field Values

variant

private final CylindricalEqualArea.Variant variant

The type of Cylindrical Equal Area projection. Possible values are:

• CylindricalEqualArea.Variant.ELLIPSOIDAL if this projection is a default variant.
• CylindricalEqualArea.Variant.SPHERICAL if this projection is the "Lambert Cylindrical Equal Area (Spherical)" case, in which case the semi-major and semi-minor axis lengths should be replaced by the authalic radius (this replacement is performed by the Initializer constructor).

Other cases may be added in the future.

Constructor Details

CylindricalEqualArea

public CylindricalEqualArea(org.opengis.referencing.operation.OperationMethod method,
 Parameters parameters)

Creates a Cylindrical Equal Area projection from the given parameters.

Parameters:

method - Description of the projection parameters.

parameters - The parameter values of the projection to create.

CylindricalEqualArea

@Workaround(library="JDK",
            version="1.7")
private CylindricalEqualArea(Initializer initializer)

Work around for RFE #4093999 in Sun's bug database ("Relax constraint on placement of this()/super() call in constructors").

CylindricalEqualArea

CylindricalEqualArea(CylindricalEqualArea 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").

createMapProjection

public org.opengis.referencing.operation.MathTransform createMapProjection(org.opengis.referencing.operation.MathTransformFactory factory)
                                                                    throws org.opengis.util.FactoryException

Returns the sequence of normalization → this → denormalization 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:

• ContextualParameters.completeTransform(MathTransformFactory, MathTransform)

transform

public org.opengis.referencing.operation.Matrix transform(double[] srcPts,
 int srcOff,
 double[] dstPts,
 int dstOff,
 boolean derivate)
                                                   throws ProjectionException

Projects the specified (λ,φ) coordinates (units in radians) and stores the result in dstPts. In addition, opportunistically computes the projection derivative if derivate is true. 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:

• AbstractMathTransform.derivative(DirectPosition)
• AbstractMathTransform.transform(DirectPosition, DirectPosition)
• MathTransforms.derivativeAndTransform(MathTransform, double[], int, double[], int)

transform

public void transform(double[] srcPts,
 int srcOff,
 double[] dstPts,
 int dstOff,
 int numPts)
               throws org.opengis.referencing.operation.TransformException

Converts a list of coordinate tuples. This method performs the same calculation than above transform(double[], int, double[], int, boolean) method, but is overridden for efficiency.

Specified by:

transform in interface org.opengis.referencing.operation.MathTransform

Overrides:

transform in class AbstractMathTransform

Parameters:

srcPts - the array containing the source point coordinates.

srcOff - the offset to the first point to be transformed in the source array.

dstPts - the array into which the transformed point coordinates are returned. May be the same than srcPts.

dstOff - the offset to the location of the first transformed point that is stored in the destination array.

numPts - the number of point objects to be transformed.

Throws:

org.opengis.referencing.operation.TransformException - if a point cannot be converted.

inverseTransform

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

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

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.