Two view of cam to one screen using stitching algorithm(OpenCV, example source code), (mosaic)

This source code based on ->
This link page introduces how to make a mosaic image from two adjacent images.
I made two cam video to one stitching video using the source code.

After run, operate the program of 3 keys.
'q' key is quit, 'p' key is processing(stitching), 'r' is reset.

Mat TwoInOneOut(Mat Left, Mat Right);

void main()
 VideoCapture stream1(0);   //0 is the id of video device.0 if you have only one camera
 VideoCapture stream2(1);   //0 is the id of video device.0 if you have only one camera
 if (!stream1.isOpened()) { //check if video device has been initialised
  cout << "cannot open camera 1";

 if (!stream2.isOpened()) { //check if video device has been initialised
  cout << "cannot open camera 2";

// namedWindow("Processing");
// namedWindow("Left");
// namedWindow("Right");

 Mat H;
 int mode=0;
 //unconditional loop
 while (true) {
  Mat cameraFrame1;
  stream1.read(cameraFrame1); //get one frame form video

  Mat cameraFrame2;
  stream2.read(cameraFrame2); //get one frame form video

  if(mode == 0)
   imshow("Left", cameraFrame1);
   imshow("Right", cameraFrame2);

  Mat Left(cameraFrame1.rows, cameraFrame1.cols, CV_8U);
  Mat Right(cameraFrame1.rows, cameraFrame1.cols, CV_8U);
  cvtColor(cameraFrame1, Left, CV_RGB2GRAY, CV_8U);
  cvtColor(cameraFrame2, Right, CV_RGB2GRAY, CV_8U);

  if (waitKey(30) == 'p')
   printf("Homography Matrix Processing\n");
   H = TwoInOneOut(Left, Right);

  if(waitKey(30) == 'r')
   printf("normal mode\n");
  //printf("%d %d\n", H.cols, H.rows);
  if(H.cols == 3 && H.rows == 3)
   Mat WarpImg( Left.rows*2, Left.cols*2, cameraFrame1.depth() );
      //printf("%d %d\n", A.depth(), A.channels());
   warpPerspective(cameraFrame2, WarpImg, H, Size(WarpImg.cols, WarpImg.rows));
   Mat tempWarpImg = WarpImg(Rect(0,0,Left.cols,Left.rows));

   Mat WarpImg( Left.rows*2, Left.cols*2, CV_8U);
      //printf("%d %d\n", A.depth(), A.channels());
   warpPerspective(Right, WarpImg, H, Size(WarpImg.cols, WarpImg.rows));
   Mat tempWarpImg = WarpImg(Rect(0,0,Left.cols,Left.rows));
   if(mode ==1)
    imshow("Processing", WarpImg );
  //Mat t = WarpImg( Rect(0,0,B.cols, B.rows));


  //imshow("Processing", t );

  if (waitKey(30) == 'q')


Mat TwoInOneOut(Mat Left, Mat Right)
 Mat H;

 if(Left.channels() != 1 || Right.channels() != 1)
  printf("Channel Error\n");
  return H;

 //Detect the keypoints using SURF Detector
    int minHessian = 300; //1500; 
    SurfFeatureDetector detector( minHessian );
 SurfDescriptorExtractor extractor;

    std::vector< KeyPoint> kp_Left;
    detector.detect( Left, kp_Left );    
 Mat des_Left;
    extractor.compute( Left, kp_Left, des_Left );

 std::vector< KeyPoint> kp_Right;
 detector.detect( Right, kp_Right );
 Mat des_Right;
 extractor.compute( Right, kp_Right, des_Right );

 std::vector< vector< DMatch > > matches;
 FlannBasedMatcher matcher;
 matcher.knnMatch(des_Left, des_Right, matches, 2);
 //matcher.knnMatch(des_Right, des_Left, matches, 2);
 std::vector< DMatch > good_matches;

 for (size_t i = 0; i < matches.size(); ++i)
  if (matches[i].size() < 2)

  const DMatch &m1 = matches[i][0];
  const DMatch &m2 = matches[i][1];

  if(m1.distance <= 0.7 * m2.distance)        

 //Draw only "good" matches
 Mat img_matches;
    drawMatches( Left, kp_Left, Right, kp_Right, good_matches, 
  img_matches, Scalar::all(-1), Scalar::all(-1), 
  vector< char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS );
 imshow("Match", img_matches);

 //Find H
 if(good_matches.size() > 20 )
  std::vector< Point2f >  LeftMatchPT;
  std::vector< Point2f >  RightMatchPT;
  for( unsigned int i = 0; i < good_matches.size(); i++ )
   //-- Get the keypoints from the good matches
   LeftMatchPT.push_back( kp_Left[ good_matches[i].queryIdx ].pt );
   RightMatchPT.push_back( kp_Right[ good_matches[i].trainIdx ].pt );

  H = findHomography( RightMatchPT, LeftMatchPT, CV_RANSAC );
  //H = findHomography( LeftMatchPT,RightMatchPT, CV_RANSAC );

 return H;


The source code
-> here


  1. hi , i am very interesting in this work , i used and modified it to stitching 2 video files , but i faced some problem , can you help me ,,, because i ma still beginner in this field and need to help ,

    when i press "p" key for processing issue, stopped and given this massage

    "Unhandled exception at 0x00007ffa68fdf8b0 in opencv.exe: 0xC0000005: Access violation reading location 0x0000000000000009."

    can you help me ????

  2. i was sent my problem and video files to your email,,, if you have a time ,,, can you help me to solve my problem ??
    waiting your replay ..
    thank you ..