Module org.apache.sis.referencing

Package org.apache.sis.referencing.operation.transform

Class PoleRotation

Object

FormattableObject

AbstractMathTransform

AbstractMathTransform2D

PoleRotation

All Implemented Interfaces:

Serializable, Parameterized, Lenient­Comparable, Math­Transform, Math­Transform2D

public class PoleRotation
extends AbstractMathTransform2D
implements Serializable

Computes latitudes and longitudes on a sphere where the south pole has been moved to given geographic coordinates. The parameter values of this transform use the conventions defined in template 3.1 of GRIB2 format published by the World Meteorological Organization (WMO):

1. φ_p: geographic latitude in degrees of the southern pole of the coordinate system.
2. λ_p: geographic longitude in degrees of the southern pole of the coordinate system.
3. Angle of rotation in degrees about the new polar axis measured clockwise when looking from the rotated pole to the Earth center.

The rotations are applied by first rotating the sphere through λ_p about the geographic polar axis, and then rotating through (φ_p − (−90°)) degrees so that the southern pole moved along the (previously rotated) Greenwich meridian.

Coordinate order

Source and target axis order in transform(…) methods is (longitude, latitude). This is the usual axis order used by Apache SIS for internal calculations (but not the parameter order in factory methods). If a different axis order is desired (for example for showing coordinates to the user), an affine transform can be concatenated to this transform.

Since:

1.2

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class AbstractMathTransform2D

Abstract­Math­Transform2D.Inverse

Field Summary

Fields inherited from class AbstractMathTransform2D

DIMENSION

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Pole­Rotation(boolean south, double φp, double λp, double θp)	Creates the non-linear part of a rotated pole operation.

Method Summary

Modifier and Type	Method	Description
protected int	compute­Hash­Code()	Computes a hash value for this transform.
boolean	equals(Object object, Comparison­Mode mode)	Compares the specified object with this math transform for equality.
protected Contextual­Parameters	get­Contextual­Parameters()	Returns the parameters used for creating the complete operation.
Parameter­Descriptor­Group	get­Parameter­Descriptors()	Returns a description of the parameters of this transform.
Parameter­Value­Group	get­Parameter­Values()	Returns a copy of the parameter values of this transform.
Math­Transform2D	inverse()	Returns the inverse transform of this object.
boolean	is­Identity()	Tests whether this transform does not move any points.
static Math­Transform	rotate­North­Pole(Math­Transform­Factory factory, double φp, double λp, double θp)	Creates a new rotated north pole operation.
static Math­Transform	rotate­South­Pole(Math­Transform­Factory factory, double φp, double λp, double θp)	Creates a new rotated south pole operation.
Matrix	transform(double[] src­Pts, int src­Off, double[] dst­Pts, int dst­Off, boolean derivate)	Transforms a single coordinate tuple in an array, and optionally computes the transform derivative at that location.
void	transform(double[] src­Pts, int src­Off, double[] dst­Pts, int dst­Off, int num­Pts)	Converts a list of coordinate tuples.

Methods inherited from class AbstractMathTransform2D

create­Transformed­Shape, derivative, get­Source­Dimensions, get­Target­Dimensions, transform

Methods inherited from class AbstractMathTransform

derivative, equals, format­To, get­Domain, hash­Code, transform, transform, transform, transform, try­Concatenate

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, to­WKT, transform, transform, transform, transform

Constructor Details

PoleRotation

protected PoleRotation(boolean south,
 double φp,
 double λp,
 double θp)

Creates the non-linear part of a rotated pole operation. This transform does not include the conversion between degrees and radians and the longitude rotations. For a complete transform, use one of the static factory methods.

Parameters:

south - true for a south pole rotation, or false for a north pole rotation.

φp - geographic latitude in degrees of the southern pole of the coordinate system.

λp - geographic longitude in degrees of the southern pole of the coordinate system.

θp - angle of rotation in degrees about the new polar axis measured clockwise when looking from the rotated pole to the Earth center.

Method Details

rotateSouthPole

public static MathTransform rotateSouthPole(MathTransformFactory factory,
 double φp,
 double λp,
 double θp)
                                     throws FactoryException

Creates a new rotated south pole operation. The rotations are applied by first rotating the sphere through λ_p about the geographic polar axis, then rotating through (φ_p − (−90°)) degrees so that the southern pole moved along the (previously rotated) Greenwich meridian, and finally by rotating θ_p degrees clockwise when looking from the southern to the northern rotated pole. In the case where θ_p=0, the 180° rotated meridian runs through both the geographical and the rotated South pole.

Parameters:

factory - the factory to use for creating the transform.

φp - geographic latitude in degrees of the southern pole of the coordinate system.

λp - geographic longitude in degrees of the southern pole of the coordinate system.

θp - angle of rotation in degrees about the new polar axis measured clockwise when looking from the southern to the northern pole.

Returns:

the conversion doing a south pole rotation.

Throws:

Factory­Exception - if an error occurred while creating a transform.

rotateNorthPole

public static MathTransform rotateNorthPole(MathTransformFactory factory,
 double φp,
 double λp,
 double θp)
                                     throws FactoryException

Creates a new rotated north pole operation. The rotations are applied by first rotating the sphere through λ_p about the geographic polar axis, then rotating through (φ_p − 90°) degrees so that the northern pole moved along the (previously rotated) Greenwich meridian, and finally by rotating θ_p degrees clockwise when looking from the northern to the southern rotated pole. In the case where θ_p=0, the 0° rotated meridian is defined as the meridian that runs through both the geographical and the rotated North pole.

The sign of the θp argument is not yet well determined. Should it be a rotation clockwise or anti-clockwise? Looking from northern to southern pole or the opposite direction? The sign may change in the future if we find an authoritative definition. In the meantime, it is safer to keep the θp value equal to zero.

Parameters:

factory - the factory to use for creating the transform.

φp - geographic latitude in degrees of the northern pole of the coordinate system.

λp - geographic longitude in degrees of the northern pole of the coordinate system.

θp - angle of rotation in degrees about the new polar axis measured clockwise when looking from the northern to the southern pole.

Returns:

the conversion doing a north pole rotation.

Throws:

Factory­Exception - if an error occurred while creating a transform.

getParameterDescriptors

@Debug
public ParameterDescriptorGroup getParameterDescriptors()

Returns a description of the parameters of this transform. The group of parameters contains only the grid (north or south) pole latitude. It does not contain the grid pole longitude or the grid angle of rotation because those parameters are handled by affine transforms pre- or post-concatenated to this transform.

Specified by:

get­Parameter­Descriptors in interface Parameterized

Overrides:

get­Parameter­Descriptors in class Abstract­Math­Transform

Returns:

the parameter descriptors for this math transform.

See Also:

• Default­Operation­Method.get­Parameters()

getParameterValues

@Debug
public ParameterValueGroup getParameterValues()

Returns a copy of the parameter values of this transform. The group contains the values of the parameters described by get­Parameter­Descriptors(). This method is mostly for debugging purposes; most GIS applications will instead be interested in the contextual parameters instead.

Specified by:

get­Parameter­Values in interface Parameterized

Overrides:

get­Parameter­Values in class Abstract­Math­Transform

Returns:

the parameter values for this math transform.

See Also:

• Abstract­Math­Transform.get­Contextual­Parameters()
• Single­Operation.get­Parameter­Values()

getContextualParameters

protected ContextualParameters getContextualParameters()

Returns the parameters used for creating the complete operation. The returned group contains not only the grid pole latitude (which is handled by this transform), but also the grid pole longitude and the grid angle of rotation (which are handled by affine transforms before or after this transform).

Overrides:

get­Contextual­Parameters in class Abstract­Math­Transform

Returns:

the parameter values for the sequence of normalize → this → denormalize transforms.

transform

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

Transforms a single coordinate tuple in an array, and optionally computes the transform derivative at that location. Source and target axis order is (longitude, latitude).

Specified by:

transform in class Abstract­Math­Transform

Parameters:

src­Pts - the array containing the source coordinates (cannot be null).

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

dst­Pts - the array into which the transformed coordinates is returned. May be the same than src­Pts. May be null if only the derivative matrix is desired.

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

derivate - true for computing the derivative, or false if not needed.

Returns:

the matrix of the transform derivative at the given source position, or null if the derivate argument is false.

Throws:

Transform­Exception - if the point cannot be transformed or if a problem occurred while calculating the derivative.

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 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 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 cannot be converted.

inverse

public MathTransform2D inverse()

Returns the inverse transform of this object.

Specified by:

inverse in interface Math­Transform

Specified by:

inverse in interface Math­Transform2D

Overrides:

inverse in class Abstract­Math­Transform2D

Returns:

the inverse of this transform.

isIdentity

public boolean isIdentity()

Tests whether this transform does not move any points.

Specified by:

is­Identity in interface Math­Transform

Overrides:

is­Identity in class Abstract­Math­Transform

Returns:

true if this transform is (at least approximately) the identity transform.

equals

public boolean equals(Object object,
 ComparisonMode mode)

Compares the specified object with this math transform for equality.

Specified by:

equals in interface Lenient­Comparable

Overrides:

equals in class Abstract­Math­Transform

Parameters:

object - the object to compare with this transform.

mode - the strictness level of the comparison.

Returns:

true if the given object is considered equals to this math transform.

See Also:

• Utilities.deep­Equals(Object, Object, Comparison­Mode)

computeHashCode

protected int computeHashCode()

Computes a hash value for this transform. This method is invoked by Abstract­Math­Transform.hash­Code() when first needed.

Overrides:

compute­Hash­Code in class Abstract­Math­Transform

Returns:

the hash code value. This value may change between different execution of the Apache SIS library.