OpenCV:如何使用createBackgroundSubtractorMOG

Question

我试图通过本教程进行 OpenCV.org：

http://docs.opencv.org/trunk/doc/tutorials/video/background_subtraction/background_subtraction.html#background-subtraction

MOG 指针初始化为

Ptr<BackgroundSubtractor> pMOG; //MOG Background subtractor

主要以下列方式使用：

pMOG = createBackgroundSubtractorMOG();

但是，这会产生以下错误：

    Error: Identifier "createBackgroundSubtractorMOG" is undefined

此外，在更新后台模型时，使用以下命令：

pMOG->apply(frame, fgMaskMOG);

这反过来又会产生以下错误：

    Error: class "cv::BackgroundSubtractor" has no member "apply"

知道对此可以

做些什么吗？提前非常感谢！

以下是整个教程代码：

//opencv
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/video/background_segm.hpp>
//C
#include <stdio.h>
//C++
#include <iostream>
#include <sstream>
using namespace cv;
using namespace std;
//global variables
Mat frame; //current frame
Mat fgMaskMOG; //fg mask generated by MOG method
Mat fgMaskMOG2; //fg mask fg mask generated by MOG2 method
Ptr<BackgroundSubtractor> pMOG; //MOG Background subtractor
Ptr<BackgroundSubtractor> pMOG2; //MOG2 Background subtractor
int keyboard;
//function declarations
void help();
void processVideo(char* videoFilename);
void processImages(char* firstFrameFilename);
void help()
{
  cout
  << "--------------------------------------------------------------------------"  << endl
  << "This program shows how to use background subtraction methods provided by "   << endl
  << " OpenCV. You can process both videos (-vid) and images (-img)."              << endl
                                                                                   << endl
  << "Usage:"                                                                      << endl
  << "./bs {-vid <video filename>|-img <image filename>}"                          << endl
  << "for example: ./bs -vid video.avi"                                            << endl
  << "or: ./bs -img /data/images/1.png"                                            << endl
  << "--------------------------------------------------------------------------"  << endl
  << endl;
}
int main(int argc, char* argv[])
{
  //print help information
  help();
  //check for the input parameter correctness
  if(argc != 3) {
    cerr <<"Incorret input list" << endl;
    cerr <<"exiting..." << endl;
    return EXIT_FAILURE;
  }
  //create GUI windows
  namedWindow("Frame");
  namedWindow("FG Mask MOG");
  namedWindow("FG Mask MOG 2");
  //create Background Subtractor objects
  pMOG = createBackgroundSubtractorMOG(); //MOG approach
  pMOG2 = createBackgroundSubtractorMOG2(); //MOG2 approach
  if(strcmp(argv[1], "-vid") == 0) {
    //input data coming from a video
    processVideo(argv[2]);
  }
  else if(strcmp(argv[1], "-img") == 0) {
    //input data coming from a sequence of images
    processImages(argv[2]);
  }
  else {
    //error in reading input parameters
    cerr <<"Please, check the input parameters." << endl;
    cerr <<"Exiting..." << endl;
    return EXIT_FAILURE;
  }
  //destroy GUI windows
  destroyAllWindows();
  return EXIT_SUCCESS;
}
void processVideo(char* videoFilename) {
  //create the capture object
  VideoCapture capture(videoFilename);
  if(!capture.isOpened()){
    //error in opening the video input
    cerr << "Unable to open video file: " << videoFilename << endl;
    exit(EXIT_FAILURE);
  }
  //read input data. ESC or 'q' for quitting
  while( (char)keyboard != 'q' && (char)keyboard != 27 ){
    //read the current frame
    if(!capture.read(frame)) {
      cerr << "Unable to read next frame." << endl;
      cerr << "Exiting..." << endl;
      exit(EXIT_FAILURE);
    }
    //update the background model
    pMOG->apply(frame, fgMaskMOG);
    pMOG2->apply(frame, fgMaskMOG2);
    //get the frame number and write it on the current frame
    stringstream ss;
    rectangle(frame, cv::Point(10, 2), cv::Point(100,20),
              cv::Scalar(255,255,255), -1);
    ss << capture.get(CAP_PROP_POS_FRAMES);
    string frameNumberString = ss.str();
    putText(frame, frameNumberString.c_str(), cv::Point(15, 15),
            FONT_HERSHEY_SIMPLEX, 0.5 , cv::Scalar(0,0,0));
    //show the current frame and the fg masks
    imshow("Frame", frame);
    imshow("FG Mask MOG", fgMaskMOG);
    imshow("FG Mask MOG 2", fgMaskMOG2);
    //get the input from the keyboard
    keyboard = waitKey( 30 );
  }
  //delete capture object
  capture.release();
}
void processImages(char* fistFrameFilename) {
  //read the first file of the sequence
  frame = imread(fistFrameFilename);
  if(!frame.data){
    //error in opening the first image
    cerr << "Unable to open first image frame: " << fistFrameFilename << endl;
    exit(EXIT_FAILURE);
  }
  //current image filename
  string fn(fistFrameFilename);
  //read input data. ESC or 'q' for quitting
  while( (char)keyboard != 'q' && (char)keyboard != 27 ){
    //update the background model
    pMOG->apply(frame, fgMaskMOG);
    pMOG2->apply(frame, fgMaskMOG2);
    //get the frame number and write it on the current frame
    size_t index = fn.find_last_of("/");
    if(index == string::npos) {
      index = fn.find_last_of("\");
    }
    size_t index2 = fn.find_last_of(".");
    string prefix = fn.substr(0,index+1);
    string suffix = fn.substr(index2);
    string frameNumberString = fn.substr(index+1, index2-index-1);
    istringstream iss(frameNumberString);
    int frameNumber = 0;
    iss >> frameNumber;
    rectangle(frame, cv::Point(10, 2), cv::Point(100,20),
              cv::Scalar(255,255,255), -1);
    putText(frame, frameNumberString.c_str(), cv::Point(15, 15),
            FONT_HERSHEY_SIMPLEX, 0.5 , cv::Scalar(0,0,0));
    //show the current frame and the fg masks
    imshow("Frame", frame);
    imshow("FG Mask MOG", fgMaskMOG);
    imshow("FG Mask MOG 2", fgMaskMOG2);
    //get the input from the keyboard
    keyboard = waitKey( 30 );
    //search for the next image in the sequence
    ostringstream oss;
    oss << (frameNumber + 1);
    string nextFrameNumberString = oss.str();
    string nextFrameFilename = prefix + nextFrameNumberString + suffix;
    //read the next frame
    frame = imread(nextFrameFilename);
    if(!frame.data){
      //error in opening the next image in the sequence
      cerr << "Unable to open image frame: " << nextFrameFilename << endl;
      exit(EXIT_FAILURE);
    }
    //update the path of the current frame
    fn.assign(nextFrameFilename);
  }
}

Answer 1

我今天碰巧遇到了这个问题。本教程适用于 opencv 3.0，不适用于 opencv 2.4+，请进行一些更改，如下所示：

//opencv
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/video/background_segm.hpp>
//C
#include <stdio.h>
//C++
#include <iostream>
#include <sstream>
using namespace cv;
using namespace std;
//global variables
Mat frame; //current frame
Mat fgMaskMOG; //fg mask generated by MOG method
Mat fgMaskMOG2; //fg mask fg mask generated by MOG2 method
Ptr<BackgroundSubtractor> pMOG; //MOG Background subtractor
Ptr<BackgroundSubtractor> pMOG2; //MOG2 Background subtractor
int keyboard;
//function declarations
void help();
void processVideo(char* videoFilename);
void processImages(char* firstFrameFilename);
void help()
{
    cout
        << "--------------------------------------------------------------------------"  << endl
        << "This program shows how to use background subtraction methods provided by "   << endl
        << " OpenCV. You can process both videos (-vid) and images (-img)."              << endl
        << endl
        << "Usage:"                                                                      << endl
        << "./bs {-vid <video filename>|-img <image filename>}"                          << endl
        << "for example: ./bs -vid video.avi"                                            << endl
        << "or: ./bs -img /data/images/1.png"                                            << endl
        << "--------------------------------------------------------------------------"  << endl
        << endl;
}
int main(int argc, char* argv[])
{
    //print help information
    help();
    //check for the input parameter correctness
    if(argc != 3) {
        cerr <<"Incorret input list" << endl;
        cerr <<"exiting..." << endl;
        return EXIT_FAILURE;
    }
    //create GUI windows
    namedWindow("Frame");
    namedWindow("FG Mask MOG");
    namedWindow("FG Mask MOG 2");
    //create Background Subtractor objects
   //NOTE HERE!!!!
    pMOG= new BackgroundSubtractorMOG(); //MOG approach
    pMOG2 = new BackgroundSubtractorMOG2(); //MOG2 approach
    if(strcmp(argv[1], "-vid") == 0) {
        //input data coming from a video
        processVideo(argv[2]);
    }
    else if(strcmp(argv[1], "-img") == 0) {
        //input data coming from a sequence of images
        processImages(argv[2]);
    }
    else {
        //error in reading input parameters
        cerr <<"Please, check the input parameters." << endl;
        cerr <<"Exiting..." << endl;
        return EXIT_FAILURE;
    }
    //destroy GUI windows
    destroyAllWindows();
    return EXIT_SUCCESS;
}
void processVideo(char* videoFilename) {
    //create the capture object
    VideoCapture capture(videoFilename);
    if(!capture.isOpened()){
        //error in opening the video input
        cerr << "Unable to open video file: " << videoFilename << endl;
        exit(EXIT_FAILURE);
    }
    //read input data. ESC or 'q' for quitting
    while( (char)keyboard != 'q' && (char)keyboard != 27 ){
        //read the current frame
        if(!capture.read(frame)) {
            cerr << "Unable to read next frame." << endl;
            cerr << "Exiting..." << endl;
            exit(EXIT_FAILURE);
        }
        //update the background model
           //AND HERE!!!
        pMOG->operator()(frame, fgMaskMOG);
        pMOG2->operator()(frame, fgMaskMOG2);
        //get the frame number and write it on the current frame
        stringstream ss;
        rectangle(frame, cv::Point(10, 2), cv::Point(100,20),
            cv::Scalar(255,255,255), -1);
        ss << capture.get(CV_CAP_PROP_POS_FRAMES);
        string frameNumberString = ss.str();
        putText(frame, frameNumberString.c_str(), cv::Point(15, 15),
            FONT_HERSHEY_SIMPLEX, 0.5 , cv::Scalar(0,0,0));
        //show the current frame and the fg masks
        imshow("Frame", frame);
        imshow("FG Mask MOG", fgMaskMOG);
        imshow("FG Mask MOG 2", fgMaskMOG2);
        //get the input from the keyboard
        keyboard = waitKey( 30 );
    }
    //delete capture object
    capture.release();
}
void processImages(char* fistFrameFilename) {
    //read the first file of the sequence
    frame = imread(fistFrameFilename);
    if(!frame.data){
        //error in opening the first image
        cerr << "Unable to open first image frame: " << fistFrameFilename << endl;
        exit(EXIT_FAILURE);
    }
    //current image filename
    string fn(fistFrameFilename);
    //read input data. ESC or 'q' for quitting
    while( (char)keyboard != 'q' && (char)keyboard != 27 ){
        //update the background model
            //ALSO HERE!!!!
        pMOG->operator()(frame, fgMaskMOG);
        pMOG2->operator()(frame, fgMaskMOG2);
        //get the frame number and write it on the current frame
        size_t index = fn.find_last_of("/");
        if(index == string::npos) {
            index = fn.find_last_of("\");
        }
        size_t index2 = fn.find_last_of(".");
        string prefix = fn.substr(0,index+1);
        string suffix = fn.substr(index2);
        string frameNumberString = fn.substr(index+1, index2-index-1);
        istringstream iss(frameNumberString);
        int frameNumber = 0;
        iss >> frameNumber;
        rectangle(frame, cv::Point(10, 2), cv::Point(100,20),
            cv::Scalar(255,255,255), -1);
        putText(frame, frameNumberString.c_str(), cv::Point(15, 15),
            FONT_HERSHEY_SIMPLEX, 0.5 , cv::Scalar(0,0,0));
        //show the current frame and the fg masks
        imshow("Frame", frame);
        imshow("FG Mask MOG", fgMaskMOG);
        imshow("FG Mask MOG 2", fgMaskMOG2);
        //get the input from the keyboard
        keyboard = waitKey( 30 );
        //search for the next image in the sequence
        ostringstream oss;
        oss << (frameNumber + 1);
        string nextFrameNumberString = oss.str();
        string nextFrameFilename = prefix + nextFrameNumberString + suffix;
        //read the next frame
        frame = imread(nextFrameFilename);
        if(!frame.data){
            //error in opening the next image in the sequence
            cerr << "Unable to open image frame: " << nextFrameFilename << endl;
            exit(EXIT_FAILURE);
        }
        //update the path of the current frame
        fn.assign(nextFrameFilename);
    }
}

Answer 2

根据前面的答案，背景减法器也可以定义为：

BackgroundSubtractorMOG MOG;

而不是：

Ptr<BackgroundSubtractor> pMOG;
pMOG= new BackgroundSubtractorMOG(); //MOG approach

这也需要在不再使用时删除 pMOG，此外，函子可用于以更智能的方式更新前景掩码：

MOG(newFrame, foregroundMask);

而不是：

pMOG->operator()(frame, fgMaskMOG);

openCV的默认假设是背景是相当恒定的，不需要任何更新，因此，在学习初始阶段之后，高斯混合不再改变。详细而清晰的描述也可以在这里找到：

http://hal.archives-ouvertes.fr/docs/00/33/82/06/PDF/RPCS_2008.pdf

Answer 3

我也有同样的问题：错误：标识符"createBackgroundSubtractorMOG"未定义，这是因为我的算法中缺少指向opencv库libopencv_video.so的链接。

我通过在项目链接期间包含 libopencv_video.so 来解决这个问题，这可以像这样在您的 Makefile 中完成： -L/usr/local/lib/libopencv_video.so

它解决了错误，我能够使用此处给出的原始教程：http://docs.opencv.org/3.0-beta/doc/tutorials/video/background_subtraction/background_subtraction.html

Answer 4

如果您希望 MOG 方法正常工作，您应该

#include "opencv2/bgsegm.hpp"

然后

pMOG = bgsegm::createBackgroundSubtractorMOG();