基于模板匹配的目标跟踪（OpenCV）

基于VS2010+ OpenCV2。代码可以读入视频，也可以读摄像头，两者的选择只需要在代码中稍微修改即可。对于视频来说，运行会先显示第一帧，然后我们用鼠标框选要跟踪的目标，然后跟踪器开始跟踪每一帧。对摄像头来说，就会一直采集图像，然后我们用鼠标框选要跟踪的目标，接着跟踪器开始跟踪后面的每一帧。具体代码如下：

#include <opencv2/opencv.hpp>  
  
using namespace cv;  
using namespace std;  
  
// Global variables  
Rect box;  
bool drawing_box = false;  
bool gotBB = false;  
  
// bounding box mouse callback  
void mouseHandler(int event, int x, int y, int flags, void *param){  
  switch( event ){  
  case CV_EVENT_MOUSEMOVE:  
    if (drawing_box){  
        box.width = x-box.x;  
        box.height = y-box.y;  
    }  
    break;  
  case CV_EVENT_LBUTTONDOWN:  
    drawing_box = true;  
    box = Rect( x, y, 0, 0 );  
    break;  
  case CV_EVENT_LBUTTONUP:  
    drawing_box = false;  
    if( box.width < 0 ){  
        box.x += box.width;  
        box.width *= -1;  
    }  
    if( box.height < 0 ){  
        box.y += box.height;  
        box.height *= -1;  
    }  
    gotBB = true;  
    break;  
  }  
}  
  
  
// tracker: get search patches around the last tracking box,  
// and find the most similar one  
void tracking(Mat frame, Mat &model, Rect &trackBox)  
{  
    Mat gray;  
    cvtColor(frame, gray, CV_RGB2GRAY);  
  
    Rect searchWindow;  
    searchWindow.width = trackBox.width * 3;  
    searchWindow.height = trackBox.height * 3;  
    searchWindow.x = trackBox.x + trackBox.width * 0.5 - searchWindow.width * 0.5;  
    searchWindow.y = trackBox.y + trackBox.height * 0.5 - searchWindow.height * 0.5;  
    searchWindow &= Rect(0, 0, frame.cols, frame.rows);  
  
    Mat similarity;  
    matchTemplate(gray(searchWindow), model, similarity, CV_TM_CCOEFF_NORMED);   
  
    double mag_r;  
    Point point;  
    minMaxLoc(similarity, 0, &mag_r, 0, &point);  
    trackBox.x = point.x + searchWindow.x;  
    trackBox.y = point.y + searchWindow.y;  
    model = gray(trackBox);  
}  
  
int main(int argc, char * argv[])  
{  
    VideoCapture capture;  
    capture.open("david.mpg");  
    bool fromfile = true;  
    //Init camera  
    if (!capture.isOpened())  
    {  
        cout << "capture device failed to open!" << endl;  
        return -1;  
    }  
    //Register mouse callback to draw the bounding box  
    cvNamedWindow("Tracker", CV_WINDOW_AUTOSIZE);  
    cvSetMouseCallback("Tracker", mouseHandler, NULL );   
  
    Mat frame, model;  
    capture >> frame;  
    while(!gotBB)  
    {  
        if (!fromfile)  
            capture >> frame;  
  
        imshow("Tracker", frame);  
        if (cvWaitKey(20) == 'q')  
            return 1;  
    }  
    //Remove callback  
    cvSetMouseCallback("Tracker", NULL, NULL );   
      
    Mat gray;  
    cvtColor(frame, gray, CV_RGB2GRAY);   
    model = gray(box);  
  
    int frameCount = 0;  
  
    while (1)  
    {  
        capture >> frame;  
        if (frame.empty())  
            return -1;  
        double t = (double)cvGetTickCount();  
        frameCount++;  
  
        // tracking  
        tracking(frame, model, box);      
  
        // show  
        stringstream buf;  
        buf << frameCount;  
        string num = buf.str();  
        putText(frame, num, Point(20, 20), FONT_HERSHEY_SIMPLEX, 1, Scalar(0, 0, 255), 3);  
        rectangle(frame, box, Scalar(0, 0, 255), 3);  
        imshow("Tracker", frame);  
  
  
        t = (double)cvGetTickCount() - t;  
        cout << "cost time: " << t / ((double)cvGetTickFrequency()*1000.) << endl;  
  
        if ( cvWaitKey(1) == 27 )  
            break;  
    }  
  
    return 0;  
}