#include <opencv2/core/utility.hpp>
#include <opencv2/tracking.hpp>
#include <opencv2/videoio.hpp>
#include <opencv2/highgui.hpp>
#include<opencv2/opencv.hpp>
#include <iostream>
#include <cstring>
using namespace std;
using namespace cv;
int main(){
VideoCapture cap;
cap.open("/media/laniakea/新加卷/ubuntu/board/train1.mp4");
if(!cap.isOpened()){
cout<<"no video";
return -1;
}
Mat frame;
Mat idontknoew;
namedWindow("input",CV_WINDOW_AUTOSIZE);
namedWindow("MOG2",CV_WINDOW_AUTOSIZE);
Ptr<BackgroundSubtractor> pMOG2 = createBackgroundSubtractorMOG2();
while (cap.read(frame))
{
imshow("input",frame);
pMOG2->apply(frame,idontknoew);
imshow("MOG2",idontknoew);
char c = waitKey(100);
if(c == 27){
break;
}
}
cap.release();
waitKey(0);
return 0;
}

#include<opencv2/opencv.hpp>
#include <iostream>
#include <string.h>
using namespace std;
using namespace cv;
Rect roi;
void processFrame(Mat &binary, Rect &rect)
{
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
findContours(binary,contours,hierarchy,RETR_EXTERNAL,CHAIN_APPROX_SIMPLE,Point(0,0));
if (contours.size() > 0){
double maxArea = 0.0;
for (size_t t = 0; t < contours.size(); t++){
double area = contourArea(contours[static_cast<int>(t)]);//最大外接矩形
if (area > maxArea){
maxArea = area;
rect = boundingRect(contours[static_cast<int>(t)]);
  }
    }
      }
else {
rect.x = rect.y = rect.width = rect.height = 0;
  }
}

int main(){
  VideoCapture cap;
  cap.open("/media/laniakea/新加卷/ubuntu/board/train1.mp4");
  if(!cap.isOpened()){
    cout<<"no file to open \n";
    return -1;
  }
  Mat frame,mask;
  namedWindow("input",CV_WINDOW_AUTOSIZE);
  namedWindow("mask",CV_WINDOW_AUTOSIZE);
  Mat kernel1 = getStructuringElement(MORPH_RECT, Size(3, 3), Point(-1, -1));//(-1,-1) 默認中心位置
  Mat kernel2 = getStructuringElement(MORPH_RECT, Size(5, 5), Point(-1, -1));
  while (cap.read(frame)){ 
 inRange(frame,Scalar(0,0,107),Scalar(90,90,255),mask);
//2 形態(tài)學操作提取
  morphologyEx(mask, mask, MORPH_OPEN, kernel1, Point(-1, -1), 1); // 開操作
//3 輪廓查找
  dilate(mask, mask, kernel2, Point(-1, -1), 4);// 膨脹
  imshow("mask",mask);
  processFrame(mask,roi);
  rectangle(frame,roi,Scalar(0,255,0),3,8,0);
  //roi就是矩形
  Point p = Point(roi.tl().x,roi.tl().y);
  String s = to_string(roi.tl().x) + " ," + to_string(roi.tl().y);
        putText(frame,s,p,FONT_HERSHEY_TRIPLEX,0.8,Scalar(255,0,0),2,CV_AA);
  imshow("input",frame);
  char c = waitKey(100);
  if(c==27){
    break;
  }
    }
  cap.release();
  waitKey(0);
  return 0;
}