Module org.opengis.geoapi.example

Package org.opengis.example.referencing

Class ProjectiveTransform

Object

SimpleIdentifiedObject

SimpleTransform

ProjectiveTransform

All Implemented Interfaces:

Identifier, IdentifiedObject, CoordinateOperation, MathTransform, ReferenceIdentifier

public class ProjectiveTransform
extends SimpleTransform

A MathTransform which use a Matrix for transforming the coordinates. This transform is usually, but not necessarily, affine.

Constraints:

• The number of columns in the matrix shall be equal to the number of source dimensions + 1.
• The number of rows in the matrix shall be equal to the number of target dimensions + 1.

Performance note: This implementation is known to be slow. However, the intent is to be pedagogic, not to be efficient. Performance enhancements are left to implementers (Tip: override all transform methods expecting array arguments).

Since:

3.1

See Also:

• SimpleTransformFactory.createAffineTransform(Matrix)

Field Summary

Fields

Modifier and Type	Field	Description
protected final SimpleMatrix	matrix	The matrix used for performing the coordinate conversions.

Fields inherited from class SimpleTransform

sourceCRS, targetCRS

Fields inherited from class SimpleIdentifiedObject

authority, code

Fields inherited from interface CoordinateOperation

COORDINATE_OPERATION_ACCURACY_KEY, DOMAIN_OF_VALIDITY_KEY, OPERATION_VERSION_KEY, SCOPE_KEY

Fields inherited from interface IdentifiedObject

ALIAS_KEY, IDENTIFIERS_KEY, NAME_KEY, REMARKS_KEY

Fields inherited from interface Identifier

AUTHORITY_KEY, CODE_KEY, CODESPACE_KEY, DESCRIPTION_KEY, VERSION_KEY

Constructor Summary

Constructors

Constructor	Description
ProjectiveTransform(Citation authority, String name, CoordinateReferenceSystem sourceCRS, CoordinateReferenceSystem targetCRS, SimpleMatrix matrix)	Creates a new operation for the given name, CRS and matrix.

Method Summary

Modifier and Type	Method	Description
Matrix	derivative(DirectPosition point)	Gets the derivative of this transform.
boolean	equals(Object object)	Compares this transform with the given object for equality.
int	getSourceDimensions()	Gets the dimension of input points.
int	getTargetDimensions()	Gets the dimension of target points.
ProjectiveTransform	inverse()	Returns the inverse transform of this object.
boolean	isIdentity()	Tests whether this transform does not move any points.
DirectPosition	transform(DirectPosition ptSrc, DirectPosition ptDst)	Transforms the specified ptSrc.

Methods inherited from class SimpleTransform

getMathTransform, getOperationVersion, getSourceCRS, getTargetCRS, transform, transform, transform, transform

Methods inherited from class SimpleIdentifiedObject

getAuthority, getCode, getCodeSpace, getDomainOfValidity, getName, getScope, hashCode, toString, toWKT

Methods inherited from class Object

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

Methods inherited from interface CoordinateOperation

getCoordinateOperationAccuracy, getDomainOfValidity, getScope

Methods inherited from interface IdentifiedObject

getAlias, getIdentifiers, getName, getRemarks, toWKT

Methods inherited from interface Identifier

getDescription, getVersion

Methods inherited from interface MathTransform

toWKT

Field Details

matrix

protected final SimpleMatrix matrix

The matrix used for performing the coordinate conversions.

Constructor Details

ProjectiveTransform

public ProjectiveTransform(Citation authority,
 String name,
 CoordinateReferenceSystem sourceCRS,
 CoordinateReferenceSystem targetCRS,
 SimpleMatrix matrix)

Creates a new operation for the given name, CRS and matrix.

Parameters:

authority - organization responsible for definition of the name, or null.

name - the name of the new CRS.

sourceCRS - the source CRS to be returned by SimpleTransform.getSourceCRS(), or null.

targetCRS - the target CRS to be returned by SimpleTransform.getTargetCRS(), or null.

matrix - the matrix. See class javadoc for constraints on the matrix size.

Method Details

getSourceDimensions

public int getSourceDimensions()

Gets the dimension of input points. This is equal to the number of columns in the matrix minus one.

Specified by:

getSourceDimensions in interface MathTransform

Overrides:

getSourceDimensions in class SimpleTransform

Returns:

the dimension of input points.

See Also:

• OperationMethod.getSourceDimensions()

getTargetDimensions

public int getTargetDimensions()

Gets the dimension of target points. This is equal to the number of rows in the matrix minus one.

Specified by:

getTargetDimensions in interface MathTransform

Overrides:

getTargetDimensions in class SimpleTransform

Returns:

the dimension of input points.

See Also:

• OperationMethod.getTargetDimensions()

transform

public DirectPosition transform(DirectPosition ptSrc,
 DirectPosition ptDst)
                         throws MismatchedDimensionException

Transforms the specified ptSrc. First, this implementation computes the following matrix product:

 ┌     ┐     ┌      ┐ ┌     ┐
 │ptDst│  =  │matrix│ │ptSrc│
 │  w  │     │      │ │  1  │
 └     ┘     └      ┘ └     ┘

Then, the destination coordinate values are divided by w. Note that in the common case where the transform is affine, w = 1.

Specified by:

transform in interface MathTransform

Specified by:

transform in class SimpleTransform

Parameters:

ptSrc - the specified coordinate point to be transformed.

ptDst - the specified coordinate point that stores the result of transforming ptSrc, or null.

Returns:

the coordinate point after transforming ptSrc and storing the result in ptDst, or a newly created point if ptDst was null.

Throws:

MismatchedDimensionException - if ptSrc or ptDst does not have the expected dimension.

derivative

public Matrix derivative(DirectPosition point)

Gets the derivative of this transform. In the particular case of linear transforms, the derivative is the same at every points. Consequently, the point argument is ignored.

Specified by:

derivative in interface MathTransform

Overrides:

derivative in class SimpleTransform

Parameters:

point - ignored for a linear transform.

Returns:

the derivative (never null).

inverse

public ProjectiveTransform inverse()
                            throws NoninvertibleTransformException

Returns the inverse transform of this object. The default implementation invert the matrix and build a new ProjectiveTransform from it.

Specified by:

inverse in interface MathTransform

Overrides:

inverse in class SimpleTransform

Returns:

the inverse transform.

Throws:

NoninvertibleTransformException - if the transform cannot be inverted.

See Also:

• AffineTransform.createInverse()

isIdentity

public boolean isIdentity()

Tests whether this transform does not move any points. The default implementation delegates to SimpleMatrix.isIdentity().

Specified by:

isIdentity in interface MathTransform

Overrides:

isIdentity in class SimpleTransform

Returns:

true if this MathTransform is an identity transform; false otherwise.

See Also:

• AffineTransform.isIdentity()

equals

public boolean equals(Object object)

Compares this transform with the given object for equality.

Overrides:

equals in class SimpleTransform

Parameters:

object - the object to compare with this SimpleTransform.

Returns:

true if the given object is equal to this object.