Class cv::LineSegmentDetector#

Line segment detector class. View details

#include <opencv2/imgproc.hpp>

Collaboration diagram for cv::LineSegmentDetector:

Public Member Functions#

Public Member Functions inherited from cv::Algorithm

Return	Name	Description
	`Algorithm()`
	`~Algorithm()`
`void`	`clear()`	Clears the algorithm state.
`bool`	`empty()`	Returns true if the Algorithm is empty (e.g. in the very beginning or after unsuccessful read.
`String`	`getDefaultName()`
`void`	`read(const FileNode & fn)`	Reads algorithm parameters from a file storage.
`void`	`save(const String & filename)`
`void`	`write(` `const Ptr< FileStorage > & fs,` `const String & name = String() )`
`void`	`write(FileStorage & fs)`	Stores algorithm parameters in a file storage.
`void`	`write(` `FileStorage & fs,` `const String & name )`

Static Public Member Functions#

Static Public Member Functions inherited from cv::Algorithm

Return	Name	Description
`static Ptr< _Tp >`	`load(` `const String & filename,` `const String & objname = String() )`	Loads algorithm from the file.
`static Ptr< _Tp >`	`loadFromString(` `const String & strModel,` `const String & objname = String() )`	Loads algorithm from a String.
`static Ptr< _Tp >`	`read(const FileNode & fn)`	Reads algorithm from the file node.

Additional Inherited Members#

Detailed Description#

Line segment detector class.

following the algorithm described at Rafael12 .

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()#

cv::LineSegmentDetector::~LineSegmentDetector()

Member Function Documentation#

compareSegments()#

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

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.

Here is the call graph for this function:

detect()#

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

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.

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.

Here is the call graph for this function:

drawSegments()#

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

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.

Source file#

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

opencv2/imgproc.hpp