org.apache.sis.referencing.operation.projection

Class ObliqueStereographic

Object

FormattableObject

AbstractMathTransform

AbstractMathTransform2D

NormalizedProjection

ObliqueStereographic

All Implemented Interfaces:

Serializable, Parameterized, LenientComparable, MathTransform, MathTransform2D

public class ObliqueStereographic
extends NormalizedProjection

Oblique Stereographic projection (EPSG code 9809). See the Stereographic projection on MathWorld for an overview.

Description

The directions starting from the central point are true, but the areas and the lengths become increasingly deformed as one moves away from the center. This projection is frequently used for mapping polar areas, but can also be used for other limited areas centered on a point.

This projection involves two steps: first a conversion of geodetic coordinates to conformal coordinates (i.e. latitudes and longitudes on a conformal sphere), then a spherical stereographic projection. For this reason this projection method is sometime known as "Double Stereographic".

Note: there is another method known as "Oblique Stereographic Alternative" or sometime just "Stereographic". That alternative uses a simplified conversion computing the conformal latitude of each point on the ellipsoid. Both methods are considered valid but produce slightly different results. For this reason EPSG considers them as different projection methods.

Since:

0.7

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
ObliqueStereographic(OperationMethod method, Parameters parameters) Creates an Oblique Stereographic projection from the given parameters.

Method Summary

Methods

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.

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, 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, transform

Constructor Detail

ObliqueStereographic

public ObliqueStereographic(OperationMethod method,
                    Parameters parameters)

Creates an Oblique Stereographic projection from the given parameters. The method argument can be the description of one of the following:

• "Oblique Stereographic", also known as "Roussilhe".

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. 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)

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.