OpenCV 3.0 rc1, FarnebackOpticalFlow(dense optical flow) example source code.

This article introduces FarnebackOpticalFlow example in opencv 3.0 rc1.
FarnebackOpticalFlow class also was changed dll name to reference.

This example is similar with here(http://study.marearts.com/2014/04/opencv-study-example-source-code-for.html).


This example will help what dll and header file need to use FarnebackOpticalFlow  class.

Required Dlls are follows :
(tbb.dll is my option)

And refer to this example.

#include < iostream>  
#include < opencv2\opencv.hpp>  
#include < opencv2\highgui.hpp>  
//#include < opencv2\imgcodecs.hpp>  
#include < opencv2\videoio.hpp> 
#include < opencv2\core\cuda.hpp>
#include < opencv2\imgproc.hpp>
#include < opencv2\cudawarping.hpp>
#include < opencv2\cudaimgproc.hpp>
//#include < opencv2\cudaarithm.hpp>
#include < opencv2\cudaoptflow.hpp>


#ifdef _DEBUG             
#pragma comment(lib, "opencv_core300d.lib")     
#pragma comment(lib, "opencv_highgui300d.lib")  
//#pragma comment(lib, "opencv_imgcodecs300d.lib")  //imread
#pragma comment(lib, "opencv_videoio300d.lib") //video capture
#pragma comment(lib, "opencv_imgproc300d.lib") //line, circle
#pragma comment(lib, "opencv_cudawarping300d.lib") //cuda::resize
#pragma comment(lib, "opencv_cudaimgproc300.lib") //cuda::cvtcolor
#pragma comment(lib, "opencv_cudaarithm300d.lib") //cuda::farnebackOpticalFlow
#pragma comment(lib, "opencv_cudaoptflow300d.lib") 
#else     
#pragma comment(lib, "opencv_core300.lib")     
#pragma comment(lib, "opencv_highgui300.lib")  
//#pragma comment(lib, "opencv_imgcodecs300.lib")  //imread
#pragma comment(lib, "opencv_videoio300.lib") //video capture
#pragma comment(lib, "opencv_imgproc300.lib") // //line, circle
#pragma comment(lib, "opencv_cudawarping300.lib") //cuda::resize
#pragma comment(lib, "opencv_cudaimgproc300.lib") //cuda::cvtcolor
#pragma comment(lib, "opencv_cudaarithm300.lib") //cuda::farnebackOpticalFlow
#pragma comment(lib, "opencv_cudaoptflow300.lib") 

#endif      

using namespace std;
using namespace cv;

void drawOptFlowMap_gpu(const Mat& flow_xy, Mat& cflowmap, int step, const Scalar& color);

int main()
{

 int s = 1;

 unsigned long AAtime = 0, BBtime = 0;

 //variables  
 Mat GetImg, flow_x, flow_y, next, prvs, flow_xy;

 //gpu variable  
 cuda::GpuMat prvs_gpu, next_gpu, flow_x_gpu, flow_y_gpu, flow_xy_gpu;
 cuda::GpuMat prvs_gpu_o, next_gpu_o;
 cuda::GpuMat prvs_gpu_c, next_gpu_c;

 //file name  
 char fileName[100] = "M:\\____videoSample____\\Rendering\\Wildlife.avi";
 //video file open  
 VideoCapture stream1(fileName);   //0 is the id of video device.0 if you have only one camera
 if (!(stream1.read(GetImg))) //get one frame form video
  return 0;

 //gpu upload, resize, color convert
 prvs_gpu_o.upload(GetImg);

 
 cuda::resize(prvs_gpu_o, prvs_gpu_c, Size(GetImg.size().width / s, GetImg.size().height / s));
 cuda::cvtColor(prvs_gpu_c, prvs_gpu, CV_BGR2GRAY);

 //dense optical flow
 Ptr< cuda::FarnebackOpticalFlow > fbOF = cuda::FarnebackOpticalFlow::create();

 

 //unconditional loop
 while (true) {

  if (!(stream1.read(GetImg))) //get one frame form video     
   break;

   ///////////////////////////////////////////////////////////////////  
  //gpu upload, resize, color convert  
  next_gpu_o.upload(GetImg);
  cuda::resize(next_gpu_o, next_gpu_c, Size(GetImg.size().width / s, GetImg.size().height / s));
  cuda::cvtColor(next_gpu_c, next_gpu, CV_BGR2GRAY);
  ///////////////////////////////////////////////////////////////////  

  AAtime = getTickCount();
  //dense optical flow  
  fbOF->calc(prvs_gpu, next_gpu, flow_xy_gpu);

  BBtime = getTickCount();
  float pt = (BBtime - AAtime) / getTickFrequency();
  float fpt = 1 / pt;
  printf("%.2lf / %.2lf \n", pt, fpt);

  //copy for vector flow drawing  
  Mat cflow;
  resize(GetImg, cflow, Size(GetImg.size().width / s, GetImg.size().height / s));  
  flow_xy_gpu.download(flow_xy);
  drawOptFlowMap_gpu(flow_xy, cflow, 10, CV_RGB(0, 255, 0));
  imshow("OpticalFlowFarneback", cflow);

  ///////////////////////////////////////////////////////////////////  
  //Display gpumat  
  next_gpu.download(next);
  prvs_gpu.download(prvs);
  imshow("next", next);
  imshow("prvs", prvs);

  //prvs mat update  
  prvs_gpu = next_gpu.clone();

  if (waitKey(5) >= 0)
   break;
 }


 return 0;
}

void drawOptFlowMap_gpu(const Mat& flow_xy, Mat& cflowmap, int step, const Scalar& color)
{

 for (int y = 0; y < cflowmap.rows; y += step)
  for (int x = 0; x < cflowmap.cols; x += step)
  {
   Point2f fxy;
   fxy.x = cvRound(flow_xy.at< Vec2f >(y, x)[0] + x);
   fxy.y = cvRound(flow_xy.at< Vec2f >(y, x)[1] + y);


   cv::line(cflowmap, Point(x, y), Point(fxy.x, fxy.y), color);
   cv::circle(cflowmap, Point(fxy.x, fxy.y), 1, color, -1);

  }

}
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