Question

How can I write a command to return matrix corner detected using goodFeaturesToTrack?

goodFeaturesToTrack(gray_image, corners, maxCorners, 
          qualityLevel, minDistance,temp_image, 2, true, 0.04);

Mat harris;
harris = original_image.clone();

for (unsigned int i=0; i corners.size(); i++)
{
    circle(harris, corners[i], 3, Scalar(0, 255, 0),-1,8,0);
    cout<<"Corners Vector: " << WHAT TO WRITE HERE? << endl;
}

Answer 1

goodFeaturesToTrack returns a corner point list of type vector<Point2f>. So, to print out the corner points you could do the following:

cout << "Corner Point [" << i << "]: " << endl;
cout << "x = " << corners[i].x << endl;
cout << "y = " << corners[i].y << endl;

Also, have a look at the lkdemo.cpp, and the goodFeaturesToTrack_Demo.cpp for more examples of usage.