org.geotools.referencing.operation.builder

Class SimilarTransformBuilder

Object

MathTransformBuilder

ProjectiveTransformBuilder

SimilarTransformBuilder

public class SimilarTransformBuilder
extends ProjectiveTransformBuilder

Builds MathTransform setup as Similar transformation from a list of MappedPosition. The The calculation uses least square method. The similar transform equation:

                                                  
  [ x']   [  a -b  Tx  ] [ x ]   [ a*x - b*y + Tx ]
  [ y'] = [  b  a  Ty  ] [ y ] = [ b*x + a*y + Ty ] 

In the case that we have more identical points we can write it like this (in Matrix):

                                           
  [ x'1 ]      [ x1 -y1  1 0 ]   [ a  ]
  [ x'2 ]      [ x2 -y2  1 0 ]   [ b  ]
  [  .  ]      [      .      ]   [ Tx ]                          
  [  .  ]      [      .      ] * [ Ty ]                          
  [ x'n ]   =  [ xn  yn  1 0 ]   
  [ y'1 ]      [ y1  x1  0 1 ]   
  [ y'2 ]      [ y2  x2  0 1 ]  
  [  .  ]      [      .      ]                                      
  [  .  ]      [      .      ]                                    
  [ y'n ]      [ yn xn  0  1 ]     
    x' = A*m  

Using the least square method we get this result:

  m = (ATA)-1 ATx'  
 

Since:

2.4

Author:

Jan Jezek

Field Summary

Fields inherited from class ProjectiveTransformBuilder

A, P, X

Fields inherited from class MathTransformBuilder

mtFactory

Constructor Summary

Constructors

Constructor and Description
SimilarTransformBuilder(List<MappedPosition> vectors) Creates SimilarTransformBuilder for the set of properties.

Method Summary

Modifier and Type	Method and Description
protected void	fillAMatrix() Fills A matrix for m = (ATPA)-1 ATPx' equation
int	getMinimumPointCount() Returns the minimum number of points required by this builder, which is 2.
protected GeneralMatrix	getProjectiveMatrix() Returns the matrix for Projective transformation setup as Affine.

Methods inherited from class ProjectiveTransformBuilder

calculateLSM, computeMathTransform, fillPMatrix, fillXMatrix, getCoordinateSystemType, includeWeights

Methods inherited from class MathTransformBuilder

getDimension, getErrorStatistics, getMappedPositions, getMathTransform, getName, getSourceCRS, getSourcePoints, getTargetCRS, getTargetPoints, getTransformation, printPoints, setMappedPositions, setSourcePoints, setTargetPoints, toString

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

SimilarTransformBuilder

public SimilarTransformBuilder(List<MappedPosition> vectors)
                        throws IllegalArgumentException,
                               MismatchedDimensionException,
                               MismatchedReferenceSystemException

Creates SimilarTransformBuilder for the set of properties. The List of MappedPosition is expected.

Parameters:

vectors - list of MappedPosition

Throws:

IllegalArgumentException

MismatchedDimensionException

MismatchedReferenceSystemException

Method Detail

fillAMatrix

protected void fillAMatrix()

Description copied from class: ProjectiveTransformBuilder

Fills A matrix for m = (A^TPA)^-1 A^TPx' equation

Overrides:

fillAMatrix in class ProjectiveTransformBuilder

getMinimumPointCount

public int getMinimumPointCount()

Returns the minimum number of points required by this builder, which is 2.

Overrides:

getMinimumPointCount in class ProjectiveTransformBuilder

Returns:

Returns the minimum number of points required by this builder, which is 2.

getProjectiveMatrix

protected GeneralMatrix getProjectiveMatrix()

Returns the matrix for Projective transformation setup as Affine. The M matrix looks like this:

                                                       
 [  a  -b  Tx  ]                           
 [  b   a  Ty  ]                              
 [  0   0  1   ]                                                                   
 

Overrides:

getProjectiveMatrix in class ProjectiveTransformBuilder

Returns:

Matrix M.