boofcv.alg.geo.calibration

Class CalibrationPlanarGridZhang99

java.lang.Object

boofcv.alg.geo.calibration.CalibrationPlanarGridZhang99

public class CalibrationPlanarGridZhang99
extends java.lang.Object

Full implementation of the Zhang99 camera calibration algorithm using planar calibration targets. First linear approximations of camera parameters are computed, which are then refined using non-linear estimation. One difference from the original paper is that tangential distortion can be included. No linear estimate if found for tangential, they are estimated by initializing the non-linear estimate with all zero.

When processing the results be sure to take in account the coordinate system being left or right handed. Calibration works just fine with either coordinate system, but most 3D geometric algorithms assume a right handed coordinate system while most images are left handed.

A listener can be provide that will give status updates and allows requests for early termination. If a request for early termination is made then a RuntimeException will be thrown.

[1] Zhengyou Zhang, "Flexible Camera Calibration By Viewing a Plane From Unknown Orientations,", International Conference on Computer Vision (ICCV'99), Corfu, Greece, pages 666-673, September 1999.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	CalibrationPlanarGridZhang99.Listener

Constructor Summary

Constructors

Constructor and Description
CalibrationPlanarGridZhang99(java.util.List<georegression.struct.point.Point2D_F64> layout, boolean assumeZeroSkew, int numRadialParam, boolean includeTangential) Configures calibration process.

Method Summary

Modifier and Type	Method and Description
static void	applyDistortion(georegression.struct.point.Point2D_F64 normPt, double[] radial, double t1, double t2) Applies radial and tangential distortion to the normalized image coordinate.
static Zhang99ParamAll	convertIntoZhangParam(java.util.List<georegression.struct.se.Se3_F64> motions, org.ejml.data.DenseMatrix64F K, boolean assumeZeroSkew, double[] distort, boolean includeTangential) Converts results fond in the linear algorithms into Zhang99ParamAll
Zhang99ParamAll	getOptimized()
protected Zhang99ParamAll	initialParam(java.util.List<CalibrationObservation> observations) Find an initial estimate for calibration parameters using linear techniques.
boolean	optimizedParam(java.util.List<CalibrationObservation> observations, java.util.List<georegression.struct.point.Point2D_F64> grid, Zhang99ParamAll initial, Zhang99ParamAll found, org.ddogleg.optimization.UnconstrainedLeastSquares optimizer) Use non-linear optimization to improve the parameter estimates
boolean	process(java.util.List<CalibrationObservation> observations) Processes observed calibration point coordinates and computes camera intrinsic and extrinsic parameters.
void	setListener(CalibrationPlanarGridZhang99.Listener listener) Used to listen in on progress and request that processing be stopped
void	setOptimizer(org.ddogleg.optimization.UnconstrainedLeastSquares optimizer) Specify which optimization algorithm to use
static int	totalPoints(java.util.List<CalibrationObservation> observations)

Methods inherited from class java.lang.Object

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

Constructor Detail

CalibrationPlanarGridZhang99

public CalibrationPlanarGridZhang99(java.util.List<georegression.struct.point.Point2D_F64> layout,
                                    boolean assumeZeroSkew,
                                    int numRadialParam,
                                    boolean includeTangential)

Configures calibration process.

Parameters:

layout - Layout of calibration points on the target

assumeZeroSkew - Should it assumed the camera has zero skew. Typically true.

numRadialParam - Number of radial distortion parameters to consider. Typically 0,1,2.

includeTangential - Should it include tangential distortion?

Method Detail

setListener

public void setListener(CalibrationPlanarGridZhang99.Listener listener)

Used to listen in on progress and request that processing be stopped

Parameters:

listener - The listener

process

public boolean process(java.util.List<CalibrationObservation> observations)

Processes observed calibration point coordinates and computes camera intrinsic and extrinsic parameters.

Parameters:

observations - Set of observed grid locations in pixel coordinates.

Returns:

true if successful and false if it failed

initialParam

protected Zhang99ParamAll initialParam(java.util.List<CalibrationObservation> observations)

Find an initial estimate for calibration parameters using linear techniques.

optimizedParam

public boolean optimizedParam(java.util.List<CalibrationObservation> observations,
                              java.util.List<georegression.struct.point.Point2D_F64> grid,
                              Zhang99ParamAll initial,
                              Zhang99ParamAll found,
                              org.ddogleg.optimization.UnconstrainedLeastSquares optimizer)

Use non-linear optimization to improve the parameter estimates

Parameters:

observations - Observations of calibration points in each image

grid - Location of calibration points on calibration target

initial - Initial estimate of calibration parameters.

found - The refined calibration parameters.

optimizer - Algorithm used to optimize parameters

convertIntoZhangParam

public static Zhang99ParamAll convertIntoZhangParam(java.util.List<georegression.struct.se.Se3_F64> motions,
                                                    org.ejml.data.DenseMatrix64F K,
                                                    boolean assumeZeroSkew,
                                                    double[] distort,
                                                    boolean includeTangential)

Converts results fond in the linear algorithms into Zhang99ParamAll

applyDistortion

public static void applyDistortion(georegression.struct.point.Point2D_F64 normPt,
                                   double[] radial,
                                   double t1,
                                   double t2)

Applies radial and tangential distortion to the normalized image coordinate.

Parameters:

normPt - point in normalized image coordinates

radial - radial distortion parameters

t1 - tangential parameter

t2 - tangential parameter

setOptimizer

public void setOptimizer(org.ddogleg.optimization.UnconstrainedLeastSquares optimizer)

Specify which optimization algorithm to use

getOptimized

public Zhang99ParamAll getOptimized()

totalPoints

public static int totalPoints(java.util.List<CalibrationObservation> observations)