Harris Corner Detector & Shi-Tomasi Corner Detector

        // Capture the current frame

        cap >> frame;

        // Resize the frame

        resize(frame, frame, Size(), scalingFactor, scalingFactor, INTER_AREA);

        dst = Mat::zeros(frame.size(), CV_32FC1);

        // Convert to grayscale

        cvtColor(frame, frameGray, COLOR_BGR2GRAY );

        // Detecting corners

        cornerHarris(frameGray, dst, blockSize, apertureSize, k, BORDER_DEFAULT);

        // Normalizing

        normalize(dst, dst_norm, 0, 255, NORM_MINMAX, CV_32FC1, Mat());

        convertScaleAbs(dst_norm, dst_norm_scaled);

        // Drawing a circle around corners

        for(int j = 0; j < dst_norm.rows ; j++)

        {

            for(int i = 0; i < dst_norm.cols; i++)

            {

                if((int)dst_norm.at<float>(j,i) > thresh)

                {

                    circle(frame, Point(i, j), 8,  Scalar(0,255,0), 2, 8, 0);

                }

            }

        }

        // Capture the current frame

        cap >> frame;

        // Resize the frame

        resize(frame, frame, Size(), scalingFactor, scalingFactor, INTER_AREA);

        // Convert to grayscale

        cvtColor(frame, frameGray, COLOR_BGR2GRAY );

        // Initialize the parameters for Shi-Tomasi algorithm

        vector<Point2f> corners;

        double qualityThreshold = 0.02;

        double minDist = 15;

        int blockSize = 5;

        bool useHarrisDetector = false;

        double k = 0.07;

        // Clone the input frame

        Mat frameCopy;

        frameCopy = frame.clone();

        // Apply corner detection

        goodFeaturesToTrack(frameGray, corners, numCorners, qualityThreshold, minDist, Mat(), blockSize, useHarrisDetector, k);

        // Parameters for the circles to display the corners

        int radius = 8;      // radius of the cirles

        int thickness = 2;   // thickness of the circles

        int lineType = 8;

        // Draw the detected corners using circles

        for(size_t i = 0; i < corners.size(); i++)

        {

            Scalar color = Scalar(rng.uniform(0,255), rng.uniform(0,255), rng.uniform(0,255));

            circle(frameCopy, corners[i], radius, color, thickness, lineType, 0);

        }