boofcv.alg.fiducial.square

Class BaseDetectFiducialSquare<T extends boofcv.struct.image.ImageGray<T>>

java.lang.Object

boofcv.alg.fiducial.square.BaseDetectFiducialSquare<T>

Direct Known Subclasses:

DetectFiducialSquareBinary, DetectFiducialSquareImage

public abstract class BaseDetectFiducialSquare<T extends boofcv.struct.image.ImageGray<T>>
extends java.lang.Object

Base class for square fiducial detectors. Searches for quadrilaterals inside the image with a black border and inner contours. It then removes perspective and lens distortion from the candidate quadrilateral and rendered onto a new image. The just mentioned image is then passed on to the class which extends this one. After being processed by the extending class, the corners are rotated to match and the 3D pose of the target found. Lens distortion is removed sparsely for performance reasons.

Must call configure(boofcv.alg.distort.LensDistortionNarrowFOV, int, int, boolean) before it can process an image.

Target orientation. Corner 0 = (-r,r), 1 = (r,r) , 2 = (r,-r) , 3 = (-r,-r).

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BaseDetectFiducialSquare.Result

Field Summary

Fields

Modifier and Type	Field and Description
protected double	borderWidthFraction
protected boolean	verbose

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BaseDetectFiducialSquare(boofcv.abst.filter.binary.InputToBinary<T> inputToBinary, boofcv.alg.shapes.polygon.DetectPolygonBinaryGrayRefine<T> squareDetector, boolean binaryCopy, double borderWidthFraction, double minimumBorderBlackFraction, int squarePixels, java.lang.Class<T> inputType) Configures the detector.

Method Summary

Modifier and Type	Method and Description
protected double	computeFractionBoundary(float pixelThreshold) Computes the fraction of pixels inside the image border which are black
void	configure(boofcv.alg.distort.LensDistortionNarrowFOV distortion, int width, int height, boolean cache) Specifies the image's intrinsic parameters and target size
boofcv.struct.image.GrayU8	getBinary()
double	getBorderWidthFraction()
org.ddogleg.struct.FastQueue<FoundFiducial>	getFound() Returns list of found fiducials
java.lang.Class<T>	getInputType()
boofcv.alg.shapes.polygon.DetectPolygonBinaryGrayRefine<T>	getSquareDetector()
double	getThresholdSideRatio()
void	process(T gray) Examines the input image to detect fiducials inside of it
protected abstract boolean	processSquare(boofcv.struct.image.GrayF32 square, BaseDetectFiducialSquare.Result result, double edgeInside, double edgeOutside) Processes the detected square and matches it to a known fiducial.
void	setThresholdSideRatio(double thresholdSideRatio)
void	setVerbose(boolean verbose) Used to toggle on/off verbose debugging information

Methods inherited from class java.lang.Object

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

Field Detail

borderWidthFraction

protected double borderWidthFraction

verbose

protected boolean verbose

Constructor Detail

BaseDetectFiducialSquare

protected BaseDetectFiducialSquare(boofcv.abst.filter.binary.InputToBinary<T> inputToBinary,
                                   boofcv.alg.shapes.polygon.DetectPolygonBinaryGrayRefine<T> squareDetector,
                                   boolean binaryCopy,
                                   double borderWidthFraction,
                                   double minimumBorderBlackFraction,
                                   int squarePixels,
                                   java.lang.Class<T> inputType)

Configures the detector.

Parameters:

inputToBinary - Converts input image into a binary image

squareDetector - Detects the quadrilaterals in the image

binaryCopy - If true a copy is created of the binary image and it's not modified.

borderWidthFraction - Fraction of the fiducial's width that the border occupies. 0.25 is recommended.

minimumBorderBlackFraction - Minimum fraction of pixels inside the border which must be black. Try 0.65

squarePixels - Number of pixels wide the undistorted square image of the fiducial's interior is. This will include the black border.

inputType - Type of input image it's processing

Method Detail

configure

public void configure(boofcv.alg.distort.LensDistortionNarrowFOV distortion,
                      int width,
                      int height,
                      boolean cache)

Specifies the image's intrinsic parameters and target size

Parameters:

distortion - Lens distortion

width - Image width

height - Image height

cache - If there's lens distortion should it cache the transforms? Speeds it up by about 12%. Ignored if no lens distortion

process

public void process(T gray)

Examines the input image to detect fiducials inside of it

Parameters:

gray - Undistorted input image

computeFractionBoundary

protected double computeFractionBoundary(float pixelThreshold)

Computes the fraction of pixels inside the image border which are black

Parameters:

pixelThreshold - Pixel's less than this value are considered black

Returns:

fraction of border that's black

getFound

public org.ddogleg.struct.FastQueue<FoundFiducial> getFound()

Returns list of found fiducials

processSquare

protected abstract boolean processSquare(boofcv.struct.image.GrayF32 square,
                                         BaseDetectFiducialSquare.Result result,
                                         double edgeInside,
                                         double edgeOutside)

Processes the detected square and matches it to a known fiducial. Black border is included.

Parameters:

square - Image of the undistorted square

result - Which target and its orientation was found

edgeInside - Average pixel value along edge inside

edgeOutside - Average pixel value along edge outside

Returns:

true if the square matches a known target.

setVerbose

public void setVerbose(boolean verbose)

Used to toggle on/off verbose debugging information

Parameters:

verbose - true for verbose output

getSquareDetector

public boofcv.alg.shapes.polygon.DetectPolygonBinaryGrayRefine<T> getSquareDetector()

getBinary

public boofcv.struct.image.GrayU8 getBinary()

getInputType

public java.lang.Class<T> getInputType()

getBorderWidthFraction

public double getBorderWidthFraction()

getThresholdSideRatio

public double getThresholdSideRatio()

setThresholdSideRatio

public void setThresholdSideRatio(double thresholdSideRatio)