org.openimaj.image.camera.calibration

Class CameraCalibrationZhang

java.lang.Object

org.openimaj.image.camera.calibration.CameraCalibrationZhang

Direct Known Subclasses:

CameraCalibration

@Reference(type=Article,
           author="Zhengyou Zhang",
           title="A flexible new technique for camera calibration",
           year="2000",
           journal="Pattern Analysis and Machine Intelligence, IEEE Transactions on",
           pages={"1330","1334"},
           month="Nov",
           number="11",
           volume="22",
           customData={"keywords","calibration;computer vision;geometry;image sensors;matrix algebra;maximum likelihood estimation;optimisation;3D computer vision;camera calibration;flexible technique;maximum likelihood criterion;planar pattern;radial lens distortion;Calibration;Cameras;Closed-form solution;Computer simulation;Computer vision;Layout;Lenses;Maximum likelihood estimation;Nonlinear distortion;Testing","doi","10.1109/34.888718","ISSN","0162-8828"})
public class CameraCalibrationZhang
extends Object

Implementation of Zhengyou Zhang's camera calibration routine using a planar calibration pattern. This calibration routine assumes a camera with a 2-term radial distortion; the third radial distortion term (k3) and tangential terms (p1, p1) of the CameraIntrinsics will be set to zero.

Author:

Jonathon Hare (jsh2@ecs.soton.ac.uk)

Field Summary

Fields

Modifier and Type	Field and Description
protected List<Camera>	cameras
protected List<List<? extends IndependentPair<? extends Point2d,? extends Point2d>>>	points

Constructor Summary

Constructors

Constructor and Description
CameraCalibrationZhang(List<List<? extends IndependentPair<? extends Point2d,? extends Point2d>>> points, int width, int height) Calibrate a camera using Zhang's method based on the given model-image point pairs across a number of images.

Method Summary

Modifier and Type	Method and Description
protected org.apache.commons.math3.linear.RealVector	buildObservedVector() Stack the observed image locations of the calibration pattern points into a vector
double	calculateError() Compute the average per-pixel error (in pixels)
protected void	estimateIntrisicAndExtrinsics(List<Jama.Matrix> homographies, int width, int height) Compute the initial estimate of the intrinsic parameters and then the extrinsic parameters assuming zero distortion.
protected void	estimateRadialDistortion() Produce an initial estimate of the radial distortion parameters, and update the intrinsics
List<Camera>	getCameras() Get the computed (extrinsic and intrinsic) camera parameters for all images used at construction time (in the same order).
CameraIntrinsics	getIntrisics() Get the computed intrinsic parameters calculated during construction.
protected void	performCalibration(int width, int height)

Methods inherited from class java.lang.Object

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

Field Detail

points

protected List<List<? extends IndependentPair<? extends Point2d,? extends Point2d>>> points

cameras

protected List<Camera> cameras

Constructor Detail

CameraCalibrationZhang

public CameraCalibrationZhang(List<List<? extends IndependentPair<? extends Point2d,? extends Point2d>>> points,
                              int width,
                              int height)

Calibrate a camera using Zhang's method based on the given model-image point pairs across a number of images. The model points are in the world coordinate system and assumed to be on the Z=0 plane.

Parameters:

points - the pairs of model-image points to calibrate the camera with

width - the image width of the camera in pixels

height - the image height of the camera in pixels

Method Detail

performCalibration

protected void performCalibration(int width,
                                  int height)

getCameras

public List<Camera> getCameras()

Get the computed (extrinsic and intrinsic) camera parameters for all images used at construction time (in the same order).

Returns:

the camera parameters for each image

getIntrisics

public CameraIntrinsics getIntrisics()

Get the computed intrinsic parameters calculated during construction.

Returns:

the intrinsic parameters of the calibrated camera

estimateRadialDistortion

protected void estimateRadialDistortion()

Produce an initial estimate of the radial distortion parameters, and update the intrinsics

estimateIntrisicAndExtrinsics

protected void estimateIntrisicAndExtrinsics(List<Jama.Matrix> homographies,
                                             int width,
                                             int height)

Compute the initial estimate of the intrinsic parameters and then the extrinsic parameters assuming zero distortion.

Parameters:

homographies - the homographies

height -

width -

buildObservedVector

protected org.apache.commons.math3.linear.RealVector buildObservedVector()

Stack the observed image locations of the calibration pattern points into a vector

Returns:

the observed vector

calculateError

public double calculateError()

Compute the average per-pixel error (in pixels)

Returns:

the average per-pixel error