OpenCV直线检测（一）—— LSD

头文件

#include "opencv2/imgproc.hpp"

类定义

Example

#include <iostream>
#include <string>
#include "opencv2/core/core.hpp"
#include "opencv2/core/utility.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui/highgui.hpp"
using namespace std;
using namespace cv;
int main(int argc, char** argv)
{
    std::string in;
    if (argc != 2)
    {
        std::cout << "Usage: lsd_lines [input image]. Now loading ../data/building.jpg" << std::endl;
        in = "../data/building.jpg";
    }
    else
    {
        in = argv[1];
    }
    Mat image = imread(in, IMREAD_GRAYSCALE);
#if 0
    Canny(image, image, 50, 200, 3); // Apply canny edge
#endif
    // Create and LSD detector with standard or no refinement.
#if 1
    Ptr<LineSegmentDetector> ls = createLineSegmentDetector(LSD_REFINE_STD);
#else
    Ptr<LineSegmentDetector> ls = createLineSegmentDetector(LSD_REFINE_NONE);
#endif
    double start = double(getTickCount());
    vector<Vec4f> lines_std;
    // Detect the lines
    ls->detect(image, lines_std);
    double duration_ms = (double(getTickCount()) - start) * 1000 / getTickFrequency();
    std::cout << "It took " << duration_ms << " ms." << std::endl;
    // Show found lines
    Mat drawnLines(image);
    ls->drawSegments(drawnLines, lines_std);
    imshow("Standard refinement", drawnLines);
    waitKey();
    return 0;
}

LSD detector 初始化参数

CV_EXPORTS_W Ptr<LineSegmentDetector> createLineSegmentDetector(
    int _refine = LSD_REFINE_STD, double _scale = 0.8,
    double _sigma_scale = 0.6, double _quant = 2.0, double _ang_th = 22.5,
    double _log_eps = 0, double _density_th = 0.7, int _n_bins = 1024);

_refine：

LSD_REFINE_NONE：No refinement applied

LSD_REFINE_STD：Standard refinement is applied. E.g. breaking arches into smaller straighter line approximations.

LSD_REFINE_ADV：Advanced refinement. Number of false alarms is calculated, lines are refined through increase of precision, decrement in size, etc.