boofcv.alg.feature.detect.line

Class HoughTransformLinePolar

java.lang.Object

boofcv.alg.feature.detect.line.HoughTransformLinePolar

public class HoughTransformLinePolar
extends Object

Hough transform which uses a polar line representation. Each pixel that is identified as a potential line in the image is transformed into parameter space as a line. Local maximals are considered to be true lines in the image. Parameter space is discretized into a set of bins. The range can vary from +- the maximum range inside the image and the angle from 0 to PI radians. How finely discretized an image is effects line detection accuracy. If too fine lines might not be detected or it will be too noisy.

USAGE NOTE: Duplicate/very similar lines are possible due to angles being cyclical. What happens is that if a line's orientation lies along a boundary point its angles will be split up between top and bottom of the transform. When lines are extracted using non-maximum it will detects peaks at the top and bottom.

Author:

Peter Abeles

Constructor Summary

Constructors

Constructor and Description
HoughTransformLinePolar(NonMaxSuppression extractor, int numBinsRange, int numBinsAngle) Specifies parameters of transform.

Method Summary

Methods

Modifier and Type	Method and Description
org.ddogleg.struct.FastQueue<georegression.struct.line.LineParametric2D_F32>	extractLines() Searches for local maximas and converts into lines.
float[]	getFoundIntensity() Returns the intensity/edge count for each returned line.
int	getNumBinsAngle()
int	getNumBinsRange()
ImageFloat32	getTransform() Returns the Hough transform image.
void	parameterize(int x, int y) Converts the pixel coordinate into a line in parameter space
void	transform(ImageUInt8 binary) Computes the Hough transform of the image.

Methods inherited from class java.lang.Object

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

Constructor Detail

HoughTransformLinePolar

public HoughTransformLinePolar(NonMaxSuppression extractor,
                       int numBinsRange,
                       int numBinsAngle)

Specifies parameters of transform. The minimum number of points specified in the extractor is an important tuning parameter.

Parameters:

extractor - Extracts local maxima from transform space.

numBinsRange - How many bins are be used for line range.

numBinsAngle - How many bins are used for angle.

Method Detail

getNumBinsRange

public int getNumBinsRange()

getNumBinsAngle

public int getNumBinsAngle()

transform

public void transform(ImageUInt8 binary)

Computes the Hough transform of the image.

Parameters:

binary - Binary image that indicates which pixels lie on edges.

extractLines

public org.ddogleg.struct.FastQueue<georegression.struct.line.LineParametric2D_F32> extractLines()

Searches for local maximas and converts into lines.

Returns:

Found lines in the image.

parameterize

public void parameterize(int x,
                int y)

Converts the pixel coordinate into a line in parameter space

getTransform

public ImageFloat32 getTransform()

Returns the Hough transform image.

Returns:

Transform image.

getFoundIntensity

public float[] getFoundIntensity()

Returns the intensity/edge count for each returned line. Useful when doing post processing pruning.

Returns:

Array containing line intensities.