opencv c++计算轮廓的几何矩

要计算轮廓的几何矩，可以使用OpenCV中的moments函数。该函数可以计算轮廓的各种矩，包括中心矩、标准化矩和 Hu 矩等。

以下是一个简单的示例代码：

#include <opencv2/opencv.hpp>

using namespace cv;

int main()
{
    Mat image = imread("contour.jpg");
    Mat gray;
    cvtColor(image, gray, COLOR_BGR2GRAY);

    // 阈值分割
    Mat binary;
    threshold(gray, binary, 127, 255, THRESH_BINARY);

    // 查找轮廓
    std::vector<std::vector<Point>> contours;
    findContours(binary, contours, RETR_LIST, CHAIN_APPROX_SIMPLE);

    // 计算轮廓的几何矩
    for (auto contour : contours)
    {
        Moments moments = moments(contour);
        double area = moments.m00;
        double cx = moments.m10 / area;
        double cy = moments.m01 / area;
        double mu11 = moments.mu11;
        double mu20 = moments.mu20;
        double mu02 = moments.mu02;
        double nu20 = moments.nu20;
        double nu02 = moments.nu02;
        double hu1 = nu20 + nu02;
        double hu2 = pow(nu20 - nu02, 2) + 4 * pow(nu11, 2);
        double hu3 = pow(nu30 - 3 * nu12, 2) + pow(3 * nu21 - nu03, 2);
        double hu4 = pow(nu30 + nu12, 2) + pow(nu21 + nu03, 2);
        double hu5 = (nu30 - 3 * nu12) * (nu30 + nu12) * (pow(nu30 + nu12, 2) - 3 * pow(nu21 + nu03, 2)) + (3 * nu21 - nu03) * (nu21 + nu03) * (3 * pow(nu30 + nu12, 2) - pow(nu21 + nu03, 2));
        double hu6 = (nu20 - nu02) * (pow(nu30 + nu12, 2) - pow(nu21 + nu03, 2)) + 4 * nu11 * (nu30 + nu12) * (nu21 + nu03);
        double hu7 = (3 * nu21 - nu03) * (nu30 + nu12) * (pow(nu30 + nu12, 2) - 3 * pow(nu21 + nu03, 2)) - (nu30 - 3 * nu12) * (nu21 + nu03) * (3 * pow(nu30 + nu12, 2) - pow(nu21 + nu03, 2));

        std::cout << "Area: " << area << std::endl;
        std::cout << "Center: (" << cx << ", " << cy << ")" << std::endl;
        std::cout << "mu11: " << mu11 << std::endl;
        std::cout << "mu20: " << mu20 << std::endl;
        std::cout << "mu02: " << mu02 << std::endl;
        std::cout << "nu20: " << nu20 << std::endl;
        std::cout << "nu02: " << nu02 << std::endl;
        std::cout << "Hu1: " << hu1 << std::endl;
        std::cout << "Hu2: " << hu2 << std::endl;
        std::cout << "Hu3: " << hu3 << std::endl;
        std::cout << "Hu4: " << hu4 << std::endl;
        std::cout << "Hu5: " << hu5 << std::endl;
        std::cout << "Hu6: " << hu6 << std::endl;
        std::cout << "Hu7: " << hu7 << std::endl;
    }

    return 0;
}

在这个示例中，我们先对图像进行阈值分割，然后使用findContours函数查找图像中的轮廓。对于每个轮廓，我们使用moments函数计算几何矩。在这个示例中，我们计算了轮廓的面积、中心、mu11、mu20、mu02、nu20、nu02和7个Hu矩。最后，我们在控制台上输出这些值。