cv::LineSegmentDetector Class Reference

Line segment detector class. More...

#include <opencv2/imgproc.hpp>

Collaboration diagram for cv::LineSegmentDetector:

Public Member Functions
virtual	~LineSegmentDetector ()
virtual int	compareSegments (const Size &size, InputArray lines1, InputArray lines2, InputOutputArray image=noArray())=0
	Draws two groups of lines in blue and red, counting the non overlapping (mismatching) pixels.
virtual void	detect (InputArray image, OutputArray lines, OutputArray width=noArray(), OutputArray prec=noArray(), OutputArray nfa=noArray())=0
	Finds lines in the input image.
virtual void	drawSegments (InputOutputArray image, InputArray lines)=0
	Draws the line segments on a given image.
Public Member Functions inherited from cv::Algorithm
	Algorithm ()
virtual	~Algorithm ()
virtual void	clear ()
	Clears the algorithm state.
virtual bool	empty () const
	Returns true if the Algorithm is empty (e.g. in the very beginning or after unsuccessful read.
virtual String	getDefaultName () const
virtual void	read (const FileNode &fn)
	Reads algorithm parameters from a file storage.
virtual void	save (const String &filename) const
virtual void	write (FileStorage &fs) const
	Stores algorithm parameters in a file storage.
void	write (FileStorage &fs, const String &name) const

Additional Inherited Members
Static Public Member Functions inherited from cv::Algorithm
template<typename _Tp >
static Ptr< _Tp >	load (const String &filename, const String &objname=String())
	Loads algorithm from the file.
template<typename _Tp >
static Ptr< _Tp >	loadFromString (const String &strModel, const String &objname=String())
	Loads algorithm from a String.
template<typename _Tp >
static Ptr< _Tp >	read (const FileNode &fn)
	Reads algorithm from the file node.
Protected Member Functions inherited from cv::Algorithm
void	writeFormat (FileStorage &fs) const

Detailed Description

Line segment detector class.

following the algorithm described at [291] .

Note

Implementation has been removed from OpenCV version 3.4.6 to 3.4.15 and version 4.1.0 to 4.5.3 due original code license conflict. restored again after Computation of a NFA code published under the MIT license.

Constructor & Destructor Documentation

~LineSegmentDetector()

virtual cv::LineSegmentDetector::~LineSegmentDetector ( )

inlinevirtual

Member Function Documentation

compareSegments()

virtual int cv::LineSegmentDetector::compareSegments ( const Size & size, InputArray lines1, InputArray lines2, InputOutputArray image = noArray() )

pure virtual

Python:
	cv.LineSegmentDetector.compareSegments(	size, lines1, lines2[, image]	) ->	retval, image

Draws two groups of lines in blue and red, counting the non overlapping (mismatching) pixels.

Parameters

size	The size of the image, where lines1 and lines2 were found.
lines1	The first group of lines that needs to be drawn. It is visualized in blue color.
lines2	The second group of lines. They visualized in red color.
image	Optional image, where the lines will be drawn. The image should be color(3-channel) in order for lines1 and lines2 to be drawn in the above mentioned colors.

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detect()

virtual void cv::LineSegmentDetector::detect ( InputArray image, OutputArray lines, OutputArray width = noArray(), OutputArray prec = noArray(), OutputArray nfa = noArray() )

pure virtual

Python:
	cv.LineSegmentDetector.detect(	image[, lines[, width[, prec[, nfa]]]]	) ->	lines, width, prec, nfa

Finds lines in the input image.

This is the output of the default parameters of the algorithm on the above shown image.

image

Parameters

image	A grayscale (CV_8UC1) input image. If only a roi needs to be selected, use: lsd_ptr-\>detect(image(roi), lines, ...); lines += Scalar(roi.x, roi.y, roi.x, roi.y);
lines	A vector of Vec4f elements specifying the beginning and ending point of a line. Where Vec4f is (x1, y1, x2, y2), point 1 is the start, point 2 - end. Returned lines are strictly oriented depending on the gradient.
width	Vector of widths of the regions, where the lines are found. E.g. Width of line.
prec	Vector of precisions with which the lines are found.
nfa	Vector containing number of false alarms in the line region, with precision of 10%. The bigger the value, logarithmically better the detection. -1 corresponds to 10 mean false alarms 0 corresponds to 1 mean false alarm 1 corresponds to 0.1 mean false alarms This vector will be calculated only when the objects type is LSD_REFINE_ADV.

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drawSegments()

virtual void cv::LineSegmentDetector::drawSegments ( InputOutputArray image, InputArray lines )

pure virtual

Python:
	cv.LineSegmentDetector.drawSegments(	image, lines	) ->	image

Draws the line segments on a given image.

Parameters

image	The image, where the lines will be drawn. Should be bigger or equal to the image, where the lines were found.
lines	A vector of the lines that needed to be drawn.

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The documentation for this class was generated from the following file:

• opencv2/imgproc.hpp