boofcv.alg.fiducial.square

Class QuadPoseEstimator

java.lang.Object

boofcv.alg.fiducial.square.QuadPoseEstimator

public class QuadPoseEstimator
extends java.lang.Object

Estimates the pose using P3P and iterative refinement from 4 points on a plane with known locations. While this seems like it would be a trivial problem it actually takes several techniques to ensure accurate results. At a high level it uses P3P to provide an estimate. If the error is large it then uses EPNP. Which ever is better it then refines. If the target is small and directly facing the camera it will enlarge the target to estimate it's orientation. Otherwise it will over fit location since it takes a large change in orientation to influence the result.

Field Summary

Fields

Modifier and Type	Field and Description
protected double	bestError
protected georegression.struct.se.Se3_F64	bestPose
static double	FUDGE_FACTOR
protected java.util.List<georegression.struct.point.Point2D_F64>	listObs
protected boofcv.struct.distort.Point2Transform2_F64	normToPixel
protected boofcv.struct.distort.Point2Transform2_F64	pixelToNorm
protected java.util.List<boofcv.struct.geo.Point2D3D>	points
static double	SMALL_PIXELS

Constructor Summary

Constructors

Constructor and Description
QuadPoseEstimator(double refineTol, int refineIterations) Constructor which picks reasonable and generally good algorithms for pose estimation.
QuadPoseEstimator(boofcv.abst.geo.EstimateNofPnP p3p, boofcv.abst.geo.RefinePnP refine) Constructor in which internal estimation algorithms are provided

Method Summary

Modifier and Type	Method and Description
protected double	computeErrors(georegression.struct.se.Se3_F64 fiducialToCamera) Compute the sum of reprojection errors for all four points
java.util.List<boofcv.struct.geo.Point2D3D>	createCopyPoints2D3D()
protected void	enlarge(georegression.struct.shapes.Quadrilateral_F64 corners, double scale) Enlarges the quadrilateral to make it more sensitive to changes in orientation
protected boolean	estimate(georegression.struct.shapes.Quadrilateral_F64 cornersPixels, georegression.struct.shapes.Quadrilateral_F64 cornersNorm, georegression.struct.se.Se3_F64 foundFiducialToCamera) Given the observed corners of the quad in the image in pixels estimate and store the results of its pose
protected void	estimateP3P(int excluded) Estimates the pose using P3P from 3 out of 4 points.
protected void	extend(georegression.struct.point.Point2D_F64 pivot, georegression.struct.point.Point2D_F64 corner, double scale)
double	getError() Reprojection error of fiducial
georegression.struct.se.Se3_F64	getWorldToCamera()
void	pixelToMarker(double pixelX, double pixelY, georegression.struct.point.Point2D_F64 marker) Given the found solution, compute the the observed pixel would appear on the marker's surface.
boolean	process(georegression.struct.shapes.Quadrilateral_F64 corners, boolean unitsPixels) Estimate the 3D pose of the camera from the observed location of the fiducial.
void	setFiducial(double x0, double y0, double x1, double y1, double x2, double y2, double x3, double y3) Specify the location of points on the 2D fiducial.
void	setLensDistoriton(boofcv.alg.distort.LensDistortionNarrowFOV distortion) Specifies the intrinsic parameters.

Methods inherited from class java.lang.Object

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

Field Detail

SMALL_PIXELS

public static final double SMALL_PIXELS

See Also:

Constant Field Values

FUDGE_FACTOR

public static final double FUDGE_FACTOR

See Also:

Constant Field Values

pixelToNorm

protected boofcv.struct.distort.Point2Transform2_F64 pixelToNorm

normToPixel

protected boofcv.struct.distort.Point2Transform2_F64 normToPixel

points

protected java.util.List<boofcv.struct.geo.Point2D3D> points

listObs

protected java.util.List<georegression.struct.point.Point2D_F64> listObs

bestError

protected double bestError

bestPose

protected georegression.struct.se.Se3_F64 bestPose

Constructor Detail

QuadPoseEstimator

public QuadPoseEstimator(double refineTol,
                         int refineIterations)

Constructor which picks reasonable and generally good algorithms for pose estimation.

Parameters:

refineTol - Convergence tolerance. Try 1e-8

refineIterations - Number of refinement iterations. Try 200

QuadPoseEstimator

public QuadPoseEstimator(boofcv.abst.geo.EstimateNofPnP p3p,
                         boofcv.abst.geo.RefinePnP refine)

Constructor in which internal estimation algorithms are provided

Method Detail

setLensDistoriton

public void setLensDistoriton(boofcv.alg.distort.LensDistortionNarrowFOV distortion)

Specifies the intrinsic parameters.

Parameters:

distortion - Intrinsic camera parameters

setFiducial

public void setFiducial(double x0,
                        double y0,
                        double x1,
                        double y1,
                        double x2,
                        double y2,
                        double x3,
                        double y3)

Specify the location of points on the 2D fiducial. These should be in "world coordinates"

pixelToMarker

public void pixelToMarker(double pixelX,
                          double pixelY,
                          georegression.struct.point.Point2D_F64 marker)

Given the found solution, compute the the observed pixel would appear on the marker's surface. pixel -> normalized pixel -> rotated -> projected on to plane

Parameters:

pixelX - (Input) pixel coordinate

pixelY - (Input) pixel coordinate

marker - (Output) location on the marker

process

public boolean process(georegression.struct.shapes.Quadrilateral_F64 corners,
                       boolean unitsPixels)

Estimate the 3D pose of the camera from the observed location of the fiducial.

MUST call setFiducial(double, double, double, double, double, double, double, double) and setLensDistoriton(boofcv.alg.distort.LensDistortionNarrowFOV) before calling this function.

Parameters:

corners - Observed corners of the fiducial.

unitsPixels - If true the specified corners are in original image pixels or false for normalized image coordinates

Returns:

true if successful or false if not

estimate

protected boolean estimate(georegression.struct.shapes.Quadrilateral_F64 cornersPixels,
                           georegression.struct.shapes.Quadrilateral_F64 cornersNorm,
                           georegression.struct.se.Se3_F64 foundFiducialToCamera)

Given the observed corners of the quad in the image in pixels estimate and store the results of its pose

estimateP3P

protected void estimateP3P(int excluded)

Estimates the pose using P3P from 3 out of 4 points. Then use all 4 to pick the best solution

Parameters:

excluded - which corner to exclude and use to check the answers from the others

enlarge

protected void enlarge(georegression.struct.shapes.Quadrilateral_F64 corners,
                       double scale)

Enlarges the quadrilateral to make it more sensitive to changes in orientation

extend

protected void extend(georegression.struct.point.Point2D_F64 pivot,
                      georegression.struct.point.Point2D_F64 corner,
                      double scale)

computeErrors

protected double computeErrors(georegression.struct.se.Se3_F64 fiducialToCamera)

Compute the sum of reprojection errors for all four points

Parameters:

fiducialToCamera - Transform being evaluated

Returns:

sum of Euclidean-squared errors

getWorldToCamera

public georegression.struct.se.Se3_F64 getWorldToCamera()

getError

public double getError()

Reprojection error of fiducial

createCopyPoints2D3D

public java.util.List<boofcv.struct.geo.Point2D3D> createCopyPoints2D3D()