OpenCV/opencv_contrib/modules/tracking/samples/tutorial_introduction_to_tracker.cpp

#include <opencv2/core/utility.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/tracking.hpp>
#include <opencv2/videoio.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>
#include <cstring>

using namespace std;
using namespace cv;

int main( int argc, char** argv ){
  // show help
  //! [help]
  if(argc<2){
    cout<<
      " Usage: tracker <video_name>\n"
      " examples:\n"
      " example_tracking_kcf Bolt/img/%04d.jpg\n"
      " example_tracking_kcf faceocc2.webm\n"
      << endl;
    return 0;
  }
  //! [help]

  // declares all required variables
  //! [vars]
  Rect roi;
  Mat frame;
  //! [vars]

  // create a tracker object
  //! [create]
  Ptr<Tracker> tracker = TrackerKCF::create();
  //! [create]

  // set input video
  //! [setvideo]
  std::string video = argv[1];
  VideoCapture cap(video);
  //! [setvideo]

  // get bounding box
  //! [getframe]
  cap >> frame;
  //! [getframe]
  //! [selectroi]
  roi=selectROI("tracker",frame);
  //! [selectroi]

  //quit if ROI was not selected
  if(roi.width==0 || roi.height==0)
    return 0;

  // initialize the tracker
  //! [init]
  tracker->init(frame,roi);
  //! [init]

  // perform the tracking process
  printf("Start the tracking process, press ESC to quit.\n");
  for ( ;; ){
    // get frame from the video
    cap >> frame;

    // stop the program if no more images
    if(frame.rows==0 || frame.cols==0)
      break;

    // update the tracking result
    //! [update]
    tracker->update(frame,roi);
    //! [update]

    //! [visualization]
    // draw the tracked object
    rectangle( frame, roi, Scalar( 255, 0, 0 ), 2, 1 );

    // show image with the tracked object
    imshow("tracker",frame);
    //! [visualization]

    //quit on ESC button
    if(waitKey(1)==27)break;
  }

  return 0;
}