boofcv.alg.shapes.polygon

Class BinaryPolygonDetector<T extends boofcv.struct.image.ImageSingleBand>

java.lang.Object

boofcv.alg.shapes.polygon.BinaryPolygonDetector<T>

public class BinaryPolygonDetector<T extends boofcv.struct.image.ImageSingleBand>
extends java.lang.Object

Detects convex polygons with the specified number of sides in an image. Shapes are assumed to be black shapes against a white background, allowing for thresholding to be used. Subpixel refinement is done using the provided implementation of RefineBinaryPolygon.

Processing Steps:

1. First the input a gray scale image and a binarized version of it.
2. The contours of black blobs are found.
3. From the contours polygons are fitted and refined to pixel accuracy.
4. (Optional) Sub-pixel refinement of the polygon's edges and/or corners.

The returned polygons will encompass the entire black polygon. Here is a simple example in 1D. If all pixels are white, but pixels ranging from 5 to 10, inclusive, then the returned boundaries would be 5.0 to 11.0. This means that coordinates 5.0 ≤ x < 11.0 are all black. 11.0 is included, but note that the entire pixel 11 is white.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BinaryPolygonDetector.Info

Field Summary

Fields

Modifier and Type	Field and Description
protected boofcv.struct.distort.PixelTransform_F32	toDistorted
protected boofcv.struct.distort.PixelTransform_F32	toUndistorted

Constructor Summary

Constructors

Constructor and Description
BinaryPolygonDetector(int minSides, int maxSides, SplitMergeLineFitLoop contourToPolygon, PolygonEdgeScore differenceScore, RefineBinaryPolygon<T> refinePolygon, double minContourFraction, boolean outputClockwise, boolean convex, boolean touchBorder, double splitPenalty, java.lang.Class<T> inputType) Configures the detector.

Method Summary

Modifier and Type	Method and Description
java.util.List<boofcv.alg.filter.binary.Contour>	getAllContours()
org.ddogleg.struct.FastQueue<georegression.struct.shapes.Polygon2D_F64>	getFoundPolygons()
java.lang.Class<T>	getInputType()
boofcv.struct.image.ImageSInt32	getLabeled()
int	getMaximumSides()
int	getMinimumSides()
RefineBinaryPolygon<T>	getRefinePolygon()
java.util.List<boofcv.alg.filter.binary.Contour>	getUsedContours()
boolean	isCheckEdgeBefore()
boolean	isConvex()
boolean	isOutputClockwise()
void	process(T gray, boofcv.struct.image.ImageUInt8 binary) Examines the undistorted gray scake input image for squares.
void	setCheckEdgeBefore(boolean checkEdgeBefore) If set to true it will prune using polygons using their edge intensity before sub-pixel optimization.
void	setConvex(boolean convex)
void	setHelper(PolygonHelper helper)
void	setLensDistortion(int width, int height, boofcv.struct.distort.PixelTransform_F32 toUndistorted, boofcv.struct.distort.PixelTransform_F32 toDistorted) Specifies transforms which can be used to change coordinates from distorted to undistorted and the opposite coordinates.
void	setNumberOfSides(int min, int max)
void	setRefinePolygon(RefineBinaryPolygon<T> refinePolygon)
void	setVerbose(boolean verbose)
protected boolean	touchesBorder(java.util.List<georegression.struct.point.Point2D_I32> contour) Checks to see if some part of the contour touches the image border.

Methods inherited from class java.lang.Object

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

Field Detail

toUndistorted

protected boofcv.struct.distort.PixelTransform_F32 toUndistorted

toDistorted

protected boofcv.struct.distort.PixelTransform_F32 toDistorted

Constructor Detail

BinaryPolygonDetector

public BinaryPolygonDetector(int minSides,
                             int maxSides,
                             SplitMergeLineFitLoop contourToPolygon,
                             PolygonEdgeScore differenceScore,
                             RefineBinaryPolygon<T> refinePolygon,
                             double minContourFraction,
                             boolean outputClockwise,
                             boolean convex,
                             boolean touchBorder,
                             double splitPenalty,
                             java.lang.Class<T> inputType)

Configures the detector.

Parameters:

minSides - minimum number of sides

maxSides - maximum number of sides

contourToPolygon - Fits a crude polygon to the shape's binary contour

differenceScore - Used to remove false positives by computing the difference along the polygon's edges If null then this test is skipped.

refinePolygon - (Optional) Refines the polygon's lines. Set to null to skip step

minContourFraction - Size of minimum contour as a fraction of the input image's width. Try 0.23

outputClockwise - If true then the order of the output polygons will be in clockwise order

convex - If true it will only return convex shapes

touchBorder - if true then shapes which touch the image border are allowed

splitPenalty - Penalty given to a line segment while splitting. See MinimizeEnergyPrune

inputType - Type of input image it's processing

Method Detail

setLensDistortion

public void setLensDistortion(int width,
                              int height,
                              boofcv.struct.distort.PixelTransform_F32 toUndistorted,
                              boofcv.struct.distort.PixelTransform_F32 toDistorted)

Specifies transforms which can be used to change coordinates from distorted to undistorted and the opposite coordinates. The undistorted image is never explicitly created.

WARNING: The undistorted image must have the same bounds as the distorted input image. This is because several of the bounds checks use the image shape. This are simplified greatly by this assumption.

Parameters:

width - Input image width. Used in sanity check only.

height - Input image height. Used in sanity check only.

toUndistorted - Transform from undistorted to distorted image.

toDistorted - Transform from distorted to undistorted image.

process

public void process(T gray,
                    boofcv.struct.image.ImageUInt8 binary)

Examines the undistorted gray scake input image for squares.

Parameters:

gray - Input image

touchesBorder

protected final boolean touchesBorder(java.util.List<georegression.struct.point.Point2D_I32> contour)

Checks to see if some part of the contour touches the image border. Most likely cropped

setHelper

public void setHelper(PolygonHelper helper)

isConvex

public boolean isConvex()

setConvex

public void setConvex(boolean convex)

getLabeled

public boofcv.struct.image.ImageSInt32 getLabeled()

isOutputClockwise

public boolean isOutputClockwise()

getFoundPolygons

public org.ddogleg.struct.FastQueue<georegression.struct.shapes.Polygon2D_F64> getFoundPolygons()

getUsedContours

public java.util.List<boofcv.alg.filter.binary.Contour> getUsedContours()

getAllContours

public java.util.List<boofcv.alg.filter.binary.Contour> getAllContours()

getInputType

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

setNumberOfSides

public void setNumberOfSides(int min,
                             int max)

getMinimumSides

public int getMinimumSides()

getMaximumSides

public int getMaximumSides()

setVerbose

public void setVerbose(boolean verbose)

isCheckEdgeBefore

public boolean isCheckEdgeBefore()

getRefinePolygon

public RefineBinaryPolygon<T> getRefinePolygon()

setRefinePolygon

public void setRefinePolygon(RefineBinaryPolygon<T> refinePolygon)

setCheckEdgeBefore

public void setCheckEdgeBefore(boolean checkEdgeBefore)

If set to true it will prune using polygons using their edge intensity before sub-pixel optimization. This should only be set to false if the initial edge is known to be off by a bit, like with a chessboard.

Parameters:

checkEdgeBefore - true for checking before and false for after.