凹点检测

#include <opencv2/opencv.hpp>
#include <iostream>

using namespace std;
using namespace cv;

Mat searchConcaveRegion(vector<vector<Point> >hull, Mat &src);
vector<Point2f> searchConcavePoint(Mat &src);

void main()
{
    Mat img = imread("C:\4.jpg",1);
    Mat gray, gray_back;

    cvtColor(img, gray, CV_BGR2GRAY);
    
    threshold(gray, gray, 0, 255, CV_THRESH_OTSU);
    gray_back = gray.clone();

    //提取轮廓
    vector<vector<Point>>contours;
    findContours(gray, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_NONE);
    drawContours(img, contours, -1, Scalar(0, 0, 255), 2);

    Mat aotu = searchConcaveRegion(contours, gray_back);
    vector<Point2f> pt;
    pt = searchConcavePoint(aotu);

    line(img, pt[pt.size() - 2], pt[pt.size() - 1], Scalar(255, 0, 0), 2, 8, 0);

    imshow("切割线", img);
    waitKey(0);
}

/**
* @brief searchConcaveRegion 寻找凹区域
* @param hull  凸包点集
* @param src  原图像（二值图）
* @return 返回 图像凹区域
*/
Mat searchConcaveRegion(vector<vector<Point> >contours, Mat &src)
{
    if (src.empty())
        return Mat();

    //遍历每个轮廓，寻找其凸包
    vector<vector<Point>>hull(contours.size());
    for (unsigned int i = 0; i<contours.size(); ++i)
    {
        convexHull(Mat(contours[i]), hull[i], false);
    }

    //绘制轮廓及其凸包
    Mat drawing = Mat::zeros(src.rows, src.cols, CV_8UC1);
    for (unsigned int i = 0; i < contours.size(); ++i)
    {
        drawContours(drawing, hull, i, Scalar(255), -1, 8, vector<Vec4i>(), 0, Point());
        drawContours(drawing, contours, i, Scalar(0), -1, 8, vector<Vec4i>(), 0, Point());
    }

    medianBlur(drawing, drawing, 3);

    imshow("凹区域", drawing);

    return drawing;
}

/**
* @brief searchConcavePoint
* @param src 凹区域图像
* @return 返回匹配好的凹点对（2个）
*/
vector<Point2f> searchConcavePoint(Mat &src)
{
    vector<Point2f> ConcavePoint;
    //轮廓寻找  
    vector<vector<Point> > contour;//用来存储轮廓  
    vector<Vec4i> hierarchys;
    findContours(src, contour, hierarchys,
        CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));  //寻找轮廓  

    //凹区域少于2要退出  
    if (contour.size()<2)
        return ConcavePoint;

    //按照轮廓面积大小排序  
    sort(contour.begin(), contour.end(), [](const vector<Point> &s1,
        const vector<Point> &s2){
        double a1 = contourArea(s1);
        double a2 = contourArea(s2);
        return a1>a2;
    });

    int minDistance = 100000000;//最短距离  
    for (int i = 0; i<contour[0].size(); ++i)
    for (int j = 0; j<contour[1].size(); ++j)
    {
        //欧氏距离  
        int d = sqrt(pow((contour[0][i].x - contour[1][j].x), 2) +
            pow((contour[0][i].y - contour[1][j].y), 2));
        if (minDistance>d)
        {
            minDistance = d;
            ConcavePoint.push_back(contour[0][i]);
            ConcavePoint.push_back(contour[1][j]);
        }
    }
    cout << "ConcavePoint0:" << ConcavePoint[ConcavePoint.size() - 2].x << "," << ConcavePoint[ConcavePoint.size() - 2].y << endl;
    cout << "ConcavePoint1:" << ConcavePoint[ConcavePoint.size() - 1].x << "," << ConcavePoint[ConcavePoint.size() - 1].y << endl;

    return ConcavePoint;
}