boofcv.alg.geo.h

Class HomographyLinear4

java.lang.Object

boofcv.alg.geo.h.HomographyLinear4

public class HomographyLinear4
extends java.lang.Object

Using linear algebra it computes a planar homography matrix using for or more points. Typically used as an initial estimate for a non-linear optimization.

The algorithm works by solving the equation below:
hat(x₂)*H*x₁ = 0
where hat(x) is the skew symmetric cross product matrix. To solve this equation is is reformatted into A*H^s=0 using the Kronecker product and the null space solved for.

Primarily based on chapter 4 in, "Multiple View Geometry in Computer Vision" 2nd Ed. but uses normalization from "An Invitation to 3-D Vision" 2004.

Constructor Summary

Constructors

Constructor and Description
HomographyLinear4(boolean normalizeInput) Configure homography calculation

Method Summary

Modifier and Type	Method and Description
boolean	process(java.util.List<AssociatedPair> points, org.ejml.data.DenseMatrix64F foundH) Computes the homography matrix given a set of observed points in two images.

Methods inherited from class java.lang.Object

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

Constructor Detail

HomographyLinear4

public HomographyLinear4(boolean normalizeInput)

Configure homography calculation

Parameters:

normalizeInput - Should image coordinate be normalized? Needed when coordinates are in units of pixels.

Method Detail

process

public boolean process(java.util.List<AssociatedPair> points,
                       org.ejml.data.DenseMatrix64F foundH)

Computes the homography matrix given a set of observed points in two images. A set of AssociatedPair is passed in. The computed homography 'H' is found such that the attributes 'keyLoc' and 'currLoc' in AssociatedPair refers to x1 and x2, respectively, in the equation below:
x₂ = H*x₁

Parameters:

points - A set of observed image points that are generated from a planar object. Minimum of 4 pairs required.

foundH - Output: Storage for the found solution. 3x3 matrix.

Returns:

true if the calculation was a success.