class cv::LineSegmentDetector

Overview

Line segment detector class. More…

#include <imgproc.hpp>

class LineSegmentDetector: public cv::Algorithm
{
public:
    // methods

    virtual
    int
    compareSegments(
        const Size& size,
        InputArray lines1,
        InputArray lines2,
        InputOutputArray _image = noArray()
        ) = 0;

    virtual
    void
    detect(
        InputArray _image,
        OutputArray _lines,
        OutputArray width = noArray(),
        OutputArray prec = noArray(),
        OutputArray nfa = noArray()
        ) = 0;

    virtual
    void
    drawSegments(
        InputOutputArray _image,
        InputArray lines
        ) = 0;
};

Inherited Members

public:
    // methods

    virtual
    void
    clear();

    virtual
    bool
    empty() const;

    virtual
    String
    getDefaultName() const;

    virtual
    void
    read(const FileNode& fn);

    virtual
    void
    save(const String& filename) const;

    virtual
    void
    write(FileStorage& fs) const;

    template <typename _Tp>
    static
    Ptr<_Tp>
    load(
        const String& filename,
        const String& objname = String()
        );

    template <typename _Tp>
    static
    Ptr<_Tp>
    loadFromString(
        const String& strModel,
        const String& objname = String()
        );

    template <typename _Tp>
    static
    Ptr<_Tp>
    read(const FileNode& fn);

protected:
    // methods

    void
    writeFormat(FileStorage& fs) const;

Detailed Documentation

Line segment detector class.

following the algorithm described at [89].

Methods

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.

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.

virtual
void
detect(
    InputArray _image,
    OutputArray _lines,
    OutputArray width = noArray(),
    OutputArray prec = noArray(),
    OutputArray nfa = noArray()
    ) = 0

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 Vec4i or Vec4f elements specifying the beginning and ending point of a line. Where Vec4i/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.

virtual
void
drawSegments(
    InputOutputArray _image,
    InputArray lines
    ) = 0

Draws the line segments on a given image.

Parameters:

_image	The image, where the liens 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.