org.apache.sis.referencing.operation.projection

Class CylindricalEqualArea

Object

FormattableObject

AbstractMathTransform

AbstractMathTransform2D

NormalizedProjection

CylindricalEqualArea

All Implemented Interfaces:

Serializable, Parameterized, LenientComparable, MathTransform, MathTransform2D

public class CylindricalEqualArea
extends NormalizedProjection

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

See Also:

Serialized Form

Defined in the sis-referencing module

Nested Class Summary

Nested classes/interfaces inherited from class NormalizedProjection

Normalized­Projection.Parameter­Role

Field Summary

Fields inherited from class NormalizedProjection

eccentricity, eccentricity­Squared

Constructor Summary

Constructors

Constructor and Description
CylindricalEqualArea(OperationMethod method, Parameters parameters) Creates a Cylindrical Equal Area projection from the given parameters.

Method Summary

Modifier and Type	Method and Description
MathTransform	createMapProjection(MathTransformFactory factory) Returns the sequence of normalization → this → denormalization transforms as a whole.
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).
Matrix	transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, boolean derivate) Converts the specified (λ,φ) coordinate (units in radians) and stores the result in dst­Pts (linear distance on a unit sphere).
void	transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts) Converts a list of coordinate points.

Methods inherited from class NormalizedProjection

compute­Hash­Code, equals, get­Contextual­Parameters, get­Parameter­Descriptors, get­Parameter­Values, inverse, try­Concatenate

Methods inherited from class AbstractMathTransform2D

create­Transformed­Shape, derivative, get­Source­Dimensions, get­Target­Dimensions, transform

Methods inherited from class AbstractMathTransform

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

Methods inherited from class FormattableObject

print, to­String, to­String, to­WKT

Methods inherited from class Object

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

Methods inherited from interface MathTransform

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

Constructor Detail

CylindricalEqualArea

public CylindricalEqualArea(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.

Method Detail

createMapProjection

public MathTransform createMapProjection(MathTransformFactory factory)
                                  throws 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 later case, this transform will 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:

Factory­Exception - if an error occurred while creating a transform.

See Also:

Contextual­Parameters.complete­Transform(Math­Transform­Factory, Math­Transform)

transform

public Matrix transform(double[] srcPts,
                        int srcOff,
                        double[] dstPts,
                        int dstOff,
                        boolean derivate)
                 throws ProjectionException

Converts the specified (λ,φ) coordinate (units in radians) and stores the result in dst­Pts (linear distance on a unit sphere). In addition, opportunistically computes the projection derivative if derivate is true.

Specified by:

transform in class Normalized­Projection

Parameters:

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

src­Off - the offset of the single coordinate to be converted in the source array.

dst­Pts - the array into which the converted coordinate is returned (may be the same than src­Pts). Ordinates 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 coordinate 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 coordinate can not 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 TransformException

Converts a list of coordinate points. 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 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:

Transform­Exception - if a point can not 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 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 not be converted.