HarrisCorner Detection in OpenCV C++

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Hi, I am trying to implement Harris corner detection in OpenCV C++ without using the built-in function CornerHarris.

This is the code I wrote and is not working. What is the mistake in the code?

int main(int argc, const char** argv)
{


    Mat src;

    Mat grad_x, grad_y;
    Mat Ixx,Ixy,Iyy;
    Mat H;
    Mat Hxx, Hxy, Hyy;
    Mat tr, det, Response;

    double sigmaX, sigmaY;
    Size gaussian_window_size = Size(3, 3);

    cv::CommandLineParser parser(argc, argv,
        "{@input   |D:/Codebases/VS_Workspace/DIP_Book_Images/chessboard.png|input image}"
    );


    const String window_name = "Harris Corner Demo ";
    int ksize = 3;
    int scale = 1;
    int delta = 0;
    int ddepth = CV_16S;


    String imageName = parser.get<String>("@input");
    src = imread(samples::findFile(imageName), IMREAD_GRAYSCALE); 
    src.convertTo(src, CV_32F);


    if (src.empty())
    {
        cout << "Error reading image " << imageName << endl;
        return EXIT_FAILURE;
    }


    Sobel(src, grad_x, ddepth, 1, 0, ksize, scale, delta, BORDER_DEFAULT);



    Sobel(src, grad_y, ddepth, 0, 1, ksize, scale, delta, BORDER_DEFAULT);


    Ixx = grad_x.mul(grad_x);
    Ixy = grad_x.mul(grad_y);
    Iyy = grad_y.mul(grad_y);



    sigmaX = 0;
    sigmaY = 0;
    GaussianBlur(Ixx, Hxx, gaussian_window_size,  sigmaX, sigmaY, BORDER_DEFAULT);
    GaussianBlur(Ixy, Hxy, gaussian_window_size,  sigmaX, sigmaY, BORDER_DEFAULT);
    GaussianBlur(Iyy, Hyy, gaussian_window_size,  sigmaX, sigmaY, BORDER_DEFAULT);

    tr = Hxx + Hyy; 
    det = Hxx.mul(Hyy) - Hxy.mul(Hxy);
    Mat tr2 = tr.mul(tr);
    Mat tr3 = tr2*0.04f;  
    Response = det - tr3;

    Mat max_resp; 
    dilate(Response, max_resp, getStructuringElement(MORPH_RECT, Size(3, 3), Point(-1, -1)));


    Mat t1, t2;
    t1 = (Response == max_resp);
    t2 = Response > 1e4;

    Mat corners = t1&t2;


    imshow(window_name, corners);

    char key = (char)waitKey(0);


    return 0;
}

• Thank you.