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#include "opencv2/video/tracking.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include <iostream>
using namespace cv;
using namespace std;
static void help()
{
cout <<
"\nThis program demonstrates dense optical flow algorithm by Gunnar Farneback\n"
"Mainly the function: calcOpticalFlowFarneback()\n"
"Call:\n"
"./fback\n"
"This reads from video camera 0\n" << endl;
}
static void drawOptFlowMap(const Mat& flow, Mat& cflowmap, int step,
double, const Scalar& color)
{
for(int y = 0; y < cflowmap.rows; y += step)
for(int x = 0; x < cflowmap.cols; x += step)
{
const Point2f& fxy = flow.at<Point2f>(y, x);
line(cflowmap, Point(x,y), Point(cvRound(x+fxy.x), cvRound(y+fxy.y)),
color);
circle(cflowmap, Point(x,y), 2, color, -1);
}
}
int main(int, char**)
{
VideoCapture cap(0);
help();
if( !cap.isOpened() )
return -1;
Mat prevgray, gray, flow, cflow, frame;
namedWindow("flow", 1);
for(;;)
{
cap >> frame;
cvtColor(frame, gray, COLOR_BGR2GRAY);
if( prevgray.data )
{
calcOpticalFlowFarneback(prevgray, gray, flow, 0.5, 3, 15, 3, 5, 1.2, 0);
cvtColor(prevgray, cflow, COLOR_GRAY2BGR);
drawOptFlowMap(flow, cflow, 16, 1.5, Scalar(0, 255, 0));
imshow("flow", cflow);
}
if(waitKey(30)>=0)
break;
std::swap(prevgray, gray);
}
return 0;
}
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