opticalflow + openCV

#include "stdafx.h"

#include <iostream>
#include "opencv2/opencv.hpp"
using namespace std;
using namespace cv;
#define UNKNOWN_FLOW_THRESH 1e9
 // Color encoding of flow vectors from:
 // http://members.shaw.ca/quadibloc/other/colint.htm
 // This code is modified from: 
 // http://vision.middlebury.edu/flow/data/
 
 
void makecolorwheel(vector<Scalar> &colorwheel)
{
 
int RY = 15;
int YG = 6;
int GC = 4;
int CB = 11;
int BM = 13;
int MR = 6;
int i;
for (i = 0; i < RY; i++) colorwheel.push_back(Scalar(255,255*i/RY,0));
for (i = 0; i < YG;i++) colorwheel.push_back(Scalar(255-255*i/YG,255,0));
for (i = 0; i < GC; i++) colorwheel.push_back(Scalar(0,255,255*i/GC));
for (i = 0; i < BM; i++) colorwheel.push_back(Scalar(255*i/BM,0,255));
for (i = 0; i < MR; i++) colorwheel.push_back(Scalar(255,0,255-255*i/MR));
 
 
}
 
void motionToColor(Mat flow,Mat &color)
{
 
  if (color.empty())
  color.create(flow.rows, flow.cols, CV_8UC3);
 
static vector<Scalar> colorwheel; //Scalar r,g,b 
    if(colorwheel.empty())
    makecolorwheel(colorwheel);
 
// determine motion range: 
  float maxrad = -1;
 // Find max flow to normalize fx and fy 
 for (int i= 0; i < flow.rows; ++i)
{
 
   for (int j = 0; j < flow.cols; ++j)
   {
 
    Vec2f flow_at_point=flow.at<Vec2f>(i,j);
       float fx=flow_at_point[0];
float fy = flow_at_point[1];
 if ((fabs(fx)>UNKNOWN_FLOW_THRESH)||(fabs(fy)>UNKNOWN_FLOW_THRESH))
continue;
      float rad = sqrt(fx * fx + fy * fy);
      maxrad = maxrad > rad ? maxrad : rad;
    
}
  
}
for(int i= 0; i < flow.rows; ++i)
     {
 
for(int j = 0;j<flow.cols;++j)
{
 
            uchar *data =color.data+color.step[0]* i+ color.step[1] * j;
Vec2f flow_at_point=flow.at<Vec2f>(i,j);
float fx =flow_at_point[0]/maxrad;
float fy = flow_at_point[1] / maxrad;
          if ((fabs(fx)>UNKNOWN_FLOW_THRESH)||(fabs(fy)>UNKNOWN_FLOW_THRESH))
{
 
          data[0] = data[1]=data[2]=0;
              continue;
           
}
        float rad = sqrt(fx*fx+fy*fy);
        float angle = atan2(-fy, -fx)/CV_PI;
         float fk = (angle + 1.0)/ 2.0 * (colorwheel.size()-1);
        int k0 = (int)fk;
      int k1=(k0 + 1) % colorwheel.size();
        float f = fk - k0;
//f = 0; // uncomment to see original color wheel 
for (int b = 0; b < 3; b++)
{
 
float col0 = colorwheel[k0][b] / 255.0;
float col1 = colorwheel[k1][b] / 255.0;
    float col = (1 - f) * col0 + f * col1;
if (rad <= 1)
        col = 1 - rad*(1 - col);// increase saturation with radius
      else
       col *= .75;// out of range
        data[2 - b] =(int)(255.0 * col);
 
}
 
}
 
}
 
}
 
  int main(int, char**)
{
 
VideoCapture cap;
cap.open(0);
cap.open("../22.avi");
 
if(!cap.isOpened())
    return -1;
 
Mat prevgray, gray, flow, cflow,frame;
Mat motion2color;
cv::Size default_size;
default_size.width = 235;
default_size.height = 189;
namedWindow("flow", 1);
 
 
for(;;)    //死循环
{
 
  double t = (double)cvGetTickCount();
 
  cap>>frame;
  cv::resize(frame, frame, default_size);
  cvtColor(frame, gray, CV_BGR2GRAY);
  imshow("original", frame);
 
  if( prevgray.data )
 {
 
    calcOpticalFlowFarneback(prevgray, gray, flow, 0.5, 3, 15, 3, 5, 1.2, 0);
     motionToColor(flow, motion2color);
    imshow("flow", motion2color);
  
}
  if(waitKey(10)>=0)
 break;
 
 std::swap(prevgray, gray);
 t=(double)cvGetTickCount() -t;
     cout <<"cost time:"<<t/((double)cvGetTickFrequency()*1000.)<<endl;
         
}
    
}