boofcv.alg.shapes.polygon

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

java.lang.Object

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

public class BinaryPolygonDetector<T extends boofcv.struct.image.ImageGray>
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.

Notes:

• If a lens distortion model is provided for lens distortion, the returned polygon will be in undistorted.

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.PixelTransform2_F32	distToUndist
protected boofcv.struct.distort.PixelTransform2_F32	undistToDist

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
void	clearLensDistortion() Discard previously set lens distortion models
java.util.List<boofcv.alg.filter.binary.Contour>	getAllContours()
boofcv.struct.distort.PixelTransform2_F32	getDistToUndist()
double	getEdgeThreshold()
org.ddogleg.struct.FastQueue<georegression.struct.shapes.Polygon2D_F64>	getFoundPolygons() List of found polygons.
java.lang.Class<T>	getInputType()
boofcv.struct.image.GrayS32	getLabeled()
int	getMaximumSides()
int	getMinimumSides()
org.ddogleg.struct.FastQueue<BinaryPolygonDetector.Info>	getPolygonInfo() Returns additional information on the polygon
RefineBinaryPolygon<T>	getRefinePolygon()
boofcv.struct.distort.PixelTransform2_F32	getUndistToDist()
java.util.List<boofcv.alg.filter.binary.Contour>	getUsedContours()
boolean	isCheckEdgeBefore()
boolean	isConvex()
boolean	isOutputClockwise()
void	process(T gray, boofcv.struct.image.GrayU8 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	setEdgeThreshold(double edgeThreshold)
void	setHelper(PolygonHelper helper)
void	setLensDistortion(int width, int height, boofcv.struct.distort.PixelTransform2_F32 distToUndist, boofcv.struct.distort.PixelTransform2_F32 undistToDist) 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

distToUndist

protected boofcv.struct.distort.PixelTransform2_F32 distToUndist

undistToDist

protected boofcv.struct.distort.PixelTransform2_F32 undistToDist

Constructor Detail

BinaryPolygonDetector

public BinaryPolygonDetector(int minSides,
                             int maxSides,
                             SplitMergeLineFitLoop contourToPolygon,
                             RefineBinaryPolygon<T> refinePolygon,
                             double minContourFraction,
                             boolean outputClockwise,
                             boolean convex,
                             boolean touchBorder,
                             double splitPenalty,
                             double edgeThreshold,
                             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

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

edgeThreshold - Polygons with an edge intensity less than this are discarded.

inputType - Type of input image it's processing

Method Detail

setLensDistortion

public void setLensDistortion(int width,
                              int height,
                              boofcv.struct.distort.PixelTransform2_F32 distToUndist,
                              boofcv.struct.distort.PixelTransform2_F32 undistToDist)

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

Parameters:

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

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

distToUndist - Transform from distorted to undistorted image.

undistToDist - Transform from undistorted to distorted image.

clearLensDistortion

public void clearLensDistortion()

Discard previously set lens distortion models

process

public void process(T gray,
                    boofcv.struct.image.GrayU8 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.GrayS32 getLabeled()

isOutputClockwise

public boolean isOutputClockwise()

getFoundPolygons

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

List of found polygons. Points are in undistorted pixels.

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)

getEdgeThreshold

public double getEdgeThreshold()

setEdgeThreshold

public void setEdgeThreshold(double edgeThreshold)

getDistToUndist

public boofcv.struct.distort.PixelTransform2_F32 getDistToUndist()

getUndistToDist

public boofcv.struct.distort.PixelTransform2_F32 getUndistToDist()

getPolygonInfo

public org.ddogleg.struct.FastQueue<BinaryPolygonDetector.Info> getPolygonInfo()

Returns additional information on the polygon

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.