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;
}