org.geotools.referencing.operation.transform
Class LinearTransform1D

Object
  extended by Formattable
      extended by AbstractMathTransform
          extended by LinearTransform1D
All Implemented Interfaces:
Serializable, LinearTransform, MathTransform, MathTransform1D

public class LinearTransform1D
extends AbstractMathTransform
implements MathTransform1D, LinearTransform, Serializable

A one dimensional, linear transform. Input values x are converted into output values y using the following equation:

y  =  offset + scale×x

This class is the same as a 2×2 affine transform. However, this specialized LinearTransform1D class is faster. It is defined there because extensively used by GridCoverage2D.

Since:
2.0
Author:
Martin Desruisseaux (IRD)
See Also:
LogarithmicTransform1D, ExponentialTransform1D, Serialized Form
Module:
modules/library/referencing (gt-referencing.jar)

Nested Class Summary
 
Nested classes/interfaces inherited from class AbstractMathTransform
AbstractMathTransform.Inverse
 
Field Summary
static LinearTransform1D IDENTITY
          The identity transform.
 double offset
          The value to add to input values.
 double scale
          The value which is multiplied to input values.
 
Fields inherited from class Formattable
SINGLE_LINE
 
Constructor Summary
protected LinearTransform1D(double scale, double offset)
          Constructs a new linear transform.
 
Method Summary
static LinearTransform1D create(double scale, double offset)
          Constructs a new linear transform.
 Matrix derivative(DirectPosition point)
          Gets the derivative of this transform at a point.
 double derivative(double value)
          Gets the derivative of this function at a value.
 boolean equals(Object object)
          Compares the specified object with this math transform for equality.
 Matrix getMatrix()
          Returns this transform as an affine transform matrix.
 ParameterDescriptorGroup getParameterDescriptors()
          Returns the parameter descriptors for this math transform.
 ParameterValueGroup getParameterValues()
          Returns the matrix elements as a group of parameters values.
 int getSourceDimensions()
          Gets the dimension of input points, which is 1.
 int getTargetDimensions()
          Gets the dimension of output points, which is 1.
 int hashCode()
          Returns a hash value for this transform.
 MathTransform1D inverse()
          Creates the inverse transform of this object.
 boolean isIdentity()
          Tests whether this transform does not move any points.
 boolean isIdentity(double tolerance)
          Tests whether this transform does not move any points by using the provided tolerance.
 double transform(double value)
          Transforms the specified value.
 void transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)
          Transforms a list of coordinate point ordinal values.
 void transform(float[] srcPts, int srcOff, float[] dstPts, int dstOff, int numPts)
          Transforms a list of coordinate point ordinal values.
 
Methods inherited from class AbstractMathTransform
createTransformedShape, derivative, ensureNonNull, formatWKT, getName, needCopy, rollLongitude, transform, transform, transform, transform
 
Methods inherited from class Formattable
cleanupThreadLocals, toString, toWKT, toWKT, toWKT
 
Methods inherited from class Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface MathTransform
toWKT, transform, transform, transform
 
Methods inherited from interface MathTransform
toWKT, transform, transform, transform
 

Field Detail

IDENTITY

public static final LinearTransform1D IDENTITY
The identity transform.


scale

public final double scale
The value which is multiplied to input values.


offset

public final double offset
The value to add to input values.

Constructor Detail

LinearTransform1D

protected LinearTransform1D(double scale,
                            double offset)
Constructs a new linear transform. This constructor is provided for subclasses only. Instances should be created using the factory method, which may returns optimized implementations for some particular argument values.

Parameters:
scale - The scale term in the linear equation.
offset - The offset term in the linear equation.
Method Detail

create

public static LinearTransform1D create(double scale,
                                       double offset)
Constructs a new linear transform.

Parameters:
scale - The scale term in the linear equation.
offset - The offset term in the linear equation.

getParameterDescriptors

public ParameterDescriptorGroup getParameterDescriptors()
Returns the parameter descriptors for this math transform.

Overrides:
getParameterDescriptors in class AbstractMathTransform
Returns:
The parameter descriptors for this math transform, or null.
See Also:
OperationMethod.getParameters()

getParameterValues

public ParameterValueGroup getParameterValues()
Returns the matrix elements as a group of parameters values. The number of parameters depends on the matrix size. Only matrix elements different from their default value will be included in this group.

Overrides:
getParameterValues in class AbstractMathTransform
Returns:
A copy of the parameter values for this math transform.
See Also:
Operation.getParameterValues()

getSourceDimensions

public int getSourceDimensions()
Gets the dimension of input points, which is 1.

Specified by:
getSourceDimensions in interface MathTransform
Specified by:
getSourceDimensions in class AbstractMathTransform

getTargetDimensions

public int getTargetDimensions()
Gets the dimension of output points, which is 1.

Specified by:
getTargetDimensions in interface MathTransform
Specified by:
getTargetDimensions in class AbstractMathTransform

getMatrix

public Matrix getMatrix()
Returns this transform as an affine transform matrix.

Specified by:
getMatrix in interface LinearTransform
Returns:
A copy of the underlying matrix.

inverse

public MathTransform1D inverse()
                        throws NoninvertibleTransformException
Creates the inverse transform of this object.

Specified by:
inverse in interface MathTransform
Specified by:
inverse in interface MathTransform1D
Overrides:
inverse in class AbstractMathTransform
Throws:
NoninvertibleTransformException

isIdentity

public boolean isIdentity()
Tests whether this transform does not move any points.

Specified by:
isIdentity in interface MathTransform
Overrides:
isIdentity in class AbstractMathTransform

isIdentity

public boolean isIdentity(double tolerance)
Tests whether this transform does not move any points by using the provided tolerance. This method work in the same way than XMatrix.isIdentity(double).

Specified by:
isIdentity in interface LinearTransform
Parameters:
tolerance - The tolerance factor.
Returns:
true if this transform is the identity one
Since:
2.3.1

derivative

public Matrix derivative(DirectPosition point)
                  throws TransformException
Gets the derivative of this transform at a point. This implementation is different from the default AbstractMathTransform.derivative(java.awt.geom.Point2D) implementation in that no coordinate point is required and Double.NaN may be a legal output value for some users.

Specified by:
derivative in interface MathTransform
Overrides:
derivative in class AbstractMathTransform
Parameters:
point - The coordinate point where to evaluate the derivative.
Returns:
The derivative at the specified point (never null).
Throws:
TransformException - if the derivative can't be evaluated at the specified point.

derivative

public double derivative(double value)
Gets the derivative of this function at a value.

Specified by:
derivative in interface MathTransform1D

transform

public double transform(double value)
Transforms the specified value.

Specified by:
transform in interface MathTransform1D

transform

public void transform(float[] srcPts,
                      int srcOff,
                      float[] dstPts,
                      int dstOff,
                      int numPts)
Transforms a list of coordinate point ordinal values.

Specified by:
transform in interface MathTransform
Overrides:
transform in class AbstractMathTransform

transform

public void transform(double[] srcPts,
                      int srcOff,
                      double[] dstPts,
                      int dstOff,
                      int numPts)
Transforms a list of coordinate point ordinal values.

Specified by:
transform in interface MathTransform

hashCode

public int hashCode()
Returns a hash value for this transform. This value need not remain consistent between different implementations of the same class.

Overrides:
hashCode in class AbstractMathTransform

equals

public boolean equals(Object object)
Compares the specified object with this math transform for equality.

Overrides:
equals in class AbstractMathTransform
Parameters:
object - The object to compare with this transform.
Returns:
true if the given object is a transform of the same class and if, given identical source position, the transformed position would be the equals.


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