initial commit

samples/cpp/tutorial_code/video/optical_flow/optical_flow.cpp

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+#include <iostream>
+#include <opencv2/core.hpp>
+#include <opencv2/highgui.hpp>
+#include <opencv2/imgproc.hpp>
+#include <opencv2/videoio.hpp>
+#include <opencv2/video.hpp>
+
+using namespace cv;
+using namespace std;
+
+int main(int argc, char **argv)
+{
+    const string about =
+        "This sample demonstrates Lucas-Kanade Optical Flow calculation.\n"
+        "The example file can be downloaded from:\n"
+        "  https://www.bogotobogo.com/python/OpenCV_Python/images/mean_shift_tracking/slow_traffic_small.mp4";
+    const string keys =
+        "{ h help |      | print this help message }"
+        "{ @image | vtest.avi | path to image file }";
+    CommandLineParser parser(argc, argv, keys);
+    parser.about(about);
+    if (parser.has("help"))
+    {
+        parser.printMessage();
+        return 0;
+    }
+    string filename = samples::findFile(parser.get<string>("@image"));
+    if (!parser.check())
+    {
+        parser.printErrors();
+        return 0;
+    }
+
+    VideoCapture capture(filename);
+    if (!capture.isOpened()){
+        //error in opening the video input
+        cerr << "Unable to open file!" << endl;
+        return 0;
+    }
+
+    // Create some random colors
+    vector<Scalar> colors;
+    RNG rng;
+    for(int i = 0; i < 100; i++)
+    {
+        int r = rng.uniform(0, 256);
+        int g = rng.uniform(0, 256);
+        int b = rng.uniform(0, 256);
+        colors.push_back(Scalar(r,g,b));
+    }
+
+    Mat old_frame, old_gray;
+    vector<Point2f> p0, p1;
+
+    // Take first frame and find corners in it
+    capture >> old_frame;
+    cvtColor(old_frame, old_gray, COLOR_BGR2GRAY);
+    goodFeaturesToTrack(old_gray, p0, 100, 0.3, 7, Mat(), 7, false, 0.04);
+
+    // Create a mask image for drawing purposes
+    Mat mask = Mat::zeros(old_frame.size(), old_frame.type());
+
+    while(true){
+        Mat frame, frame_gray;
+
+        capture >> frame;
+        if (frame.empty())
+            break;
+        cvtColor(frame, frame_gray, COLOR_BGR2GRAY);
+
+        // calculate optical flow
+        vector<uchar> status;
+        vector<float> err;
+        TermCriteria criteria = TermCriteria((TermCriteria::COUNT) + (TermCriteria::EPS), 10, 0.03);
+        calcOpticalFlowPyrLK(old_gray, frame_gray, p0, p1, status, err, Size(15,15), 2, criteria);
+
+        vector<Point2f> good_new;
+        for(uint i = 0; i < p0.size(); i++)
+        {
+            // Select good points
+            if(status[i] == 1) {
+                good_new.push_back(p1[i]);
+                // draw the tracks
+                line(mask,p1[i], p0[i], colors[i], 2);
+                circle(frame, p1[i], 5, colors[i], -1);
+            }
+        }
+        Mat img;
+        add(frame, mask, img);
+
+        imshow("Frame", img);
+
+        int keyboard = waitKey(30);
+        if (keyboard == 'q' || keyboard == 27)
+            break;
+
+        // Now update the previous frame and previous points
+        old_gray = frame_gray.clone();
+        p0 = good_new;
+    }
+}

samples/cpp/tutorial_code/video/optical_flow/optical_flow_dense.cpp

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+#include <iostream>
+#include <opencv2/core.hpp>
+#include <opencv2/highgui.hpp>
+#include <opencv2/imgproc.hpp>
+#include <opencv2/videoio.hpp>
+#include <opencv2/video.hpp>
+
+using namespace cv;
+using namespace std;
+
+int main()
+{
+    VideoCapture capture(samples::findFile("vtest.avi"));
+    if (!capture.isOpened()){
+        //error in opening the video input
+        cerr << "Unable to open file!" << endl;
+        return 0;
+    }
+
+    Mat frame1, prvs;
+    capture >> frame1;
+    cvtColor(frame1, prvs, COLOR_BGR2GRAY);
+
+    while(true){
+        Mat frame2, next;
+        capture >> frame2;
+        if (frame2.empty())
+            break;
+        cvtColor(frame2, next, COLOR_BGR2GRAY);
+
+        Mat flow(prvs.size(), CV_32FC2);
+        calcOpticalFlowFarneback(prvs, next, flow, 0.5, 3, 15, 3, 5, 1.2, 0);
+
+        // visualization
+        Mat flow_parts[2];
+        split(flow, flow_parts);
+        Mat magnitude, angle, magn_norm;
+        cartToPolar(flow_parts[0], flow_parts[1], magnitude, angle, true);
+        normalize(magnitude, magn_norm, 0.0f, 1.0f, NORM_MINMAX);
+        angle *= ((1.f / 360.f) * (180.f / 255.f));
+
+        //build hsv image
+        Mat _hsv[3], hsv, hsv8, bgr;
+        _hsv[0] = angle;
+        _hsv[1] = Mat::ones(angle.size(), CV_32F);
+        _hsv[2] = magn_norm;
+        merge(_hsv, 3, hsv);
+        hsv.convertTo(hsv8, CV_8U, 255.0);
+        cvtColor(hsv8, bgr, COLOR_HSV2BGR);
+
+        imshow("frame2", bgr);
+
+        int keyboard = waitKey(30);
+        if (keyboard == 'q' || keyboard == 27)
+            break;
+
+        prvs = next;
+    }
+}