Class ProjectiveTransform

java.lang.Object

com.vividsolutions.jump.warp.CoordinateTransform

com.vividsolutions.jump.warp.ProjectiveTransform

public class ProjectiveTransform
extends CoordinateTransform

Giuseppe Aruta (2013) This class derives from OpenJUMP original AffineTransformation class and it implements a ProjectiveTransform that is initialized by specifying four couples of points (source to target). The matrix is a dapted from http://graphics.lcs.mit.edu/classes/6.837/F01/Lecture07/lecture07.pdf

     [ x1_ ] = [  x1 y1 1  0  0  0  -x1x1_ -y1x1_ ] [ a11 ]
     [ y1_ ] = [  0  0  0  x1 y1 1  -x1y1_ -y1y1_ ] [ a12 ]
     [ x2_ ] = [  x2 y2 1  0  0  0  -x2x2_ -y2x2_ ] [ a13 ]
     [ y2_ ] = [  0  0  0  x2 y2 1  -x2y2_ -y2y2_ ] [ a21 ]
     [ x3_ ] = [  x3 y3 1  0  0  0  -x3x3_ -y3x3_ ] [ a22 ]
     [ y3_ ] = [  0  0  0  x3 y3 1  -x3y3_ -y3y3_ ] [ a23 ]
     [ x4_ ] = [  x3 y3 1  0  0  0  -x4x4_ -y4x4_ ] [ a31 ]
     [ y4_ ] = [  0  0  0  x3 y3 1  -x4y4_ -y4y4_ ] [ a32 ]

See also http://en.wikipedia.org/wiki/Homography for Homographic transformations and

Constructor Summary

Constructors

Constructor	Description
ProjectiveTransform(org.locationtech.jts.geom.Coordinate p1, org.locationtech.jts.geom.Coordinate p1_, org.locationtech.jts.geom.Coordinate p2, org.locationtech.jts.geom.Coordinate p2_, org.locationtech.jts.geom.Coordinate p3, org.locationtech.jts.geom.Coordinate p3_, org.locationtech.jts.geom.Coordinate p4, org.locationtech.jts.geom.Coordinate p4_)	A transformation that maps p1 to p1_, p2 to p2_, p3 to p3_ and p4 to p4_

Method Summary

Modifier and Type	Method	Description
org.locationtech.jts.geom.Coordinate	transform(org.locationtech.jts.geom.Coordinate c)	Applies the prospective transform to a point.

Methods inherited from class CoordinateTransform

transform, transform

Methods inherited from class Object

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

Constructor Details

ProjectiveTransform

public ProjectiveTransform(org.locationtech.jts.geom.Coordinate p1,
 org.locationtech.jts.geom.Coordinate p1_,
 org.locationtech.jts.geom.Coordinate p2,
 org.locationtech.jts.geom.Coordinate p2_,
 org.locationtech.jts.geom.Coordinate p3,
 org.locationtech.jts.geom.Coordinate p3_,
 org.locationtech.jts.geom.Coordinate p4,
 org.locationtech.jts.geom.Coordinate p4_)

A transformation that maps p1 to p1_, p2 to p2_, p3 to p3_ and p4 to p4_

Parameters:

p1 - a point

p1_ - the point p1 maps to

p2 - another point

p2_ - the point p2 maps to

p3 - another point

p3_ - the point p3 maps to

p4 - another point

p4_ - the point p4 maps to

Method Details

transform

public org.locationtech.jts.geom.Coordinate transform(org.locationtech.jts.geom.Coordinate c)

Applies the prospective transform to a point. From http://graphics.lcs.mit.edu/classes/6.837/F01/Lecture07/lecture07.pdf:

     [ wx_ ] = [  P11 P12 P13  ] [ x ]
     [ wy_ ] = [  P21 P22 P23  ] [ y ]
     [ w   ] = [  P31 P32   1  ] [ 1 ]

Specified by:

transform in class CoordinateTransform

Parameters:

c - the input to the projective transform

Returns:

the result of applying the projective transform to c