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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;
}
}
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