本章内容:

3.计算弧长
4.计算面积
5.计算中心点

输出结果：

代码

#include <ostream>
#include <opencv.hpp>
#include <math.h>

int main(int argc, char *argv[])
{
    /*
     本章内容:
        1. 轮廓查找
        2. 绘制轮廓
        3.计算弧长
        4.计算面积
        5.计算中心点
    */
    cv::String fileName = "/home/wang/dev/Image/QT.jpg";
    cv::String fileName1 = "/home/wang/dev/Image/hei.png";
    cv::Mat src = cv::imread(fileName);
    cv::Mat src1 = cv::imread(fileName1);
    if(src.data == NULL){
        printf("图像读入失败\n");
        return -1;
    }
    cv::imshow("src",src);
    cv::Mat dstCany;
    cv::Mat gray;
    cv::cvtColor(src,gray,cv::COLOR_BGR2GRAY);
    cv::Canny(gray,dstCany,50,150);
    std::vector<std::vector<cv::Point>> contours;
    std::vector<cv::Vec4i> hierarchy;
    cv::findContours(dstCany,contours,hierarchy,cv::RETR_TREE,cv::CHAIN_APPROX_SIMPLE,cv::Point(0,0));
    cv::RNG rng(1234);
    cv::Mat dst(src.size(),src.type());

    std::cout << "轮廓数量" << contours.size() << std::endl;
    for(int i=0; i <contours.size();i++){
        cv::Scalar color = cv::Scalar(rng.uniform(0,255),rng.uniform(0,255),rng.uniform(0,255));
        cv::drawContours(dst,contours,i,color,4);
        // 计算弧长，CV_EXPORTS_W double arcLength( InputArray curve, bool closed );
        double arcLen = cv::arcLength(contours[i],false);
        printf("arcLen[%d]=%f",i,arcLen);
        // 计算面积
        double area = cv::contourArea(contours[i],true);
        printf(" contourArea[%d]=%f\t",i,area);
        //计算矩 CV_EXPORTS_W Moments moments( InputArray array, bool binaryImage = false );
        cv::Moments Mom;
        Mom = cv::moments(contours[i]);
        // 计算中心
        double cx = Mom.m10/Mom.m00;
        double cy = Mom.m01/Mom.m00;
        printf(" cy=%f,cy=%f",cy,cy);
        std::cout<< std::endl;

        if(i > 10) break;
    }
    cv::imshow("dst",dst);
    cv::waitKey(0);
    return 1;
}