Opencv Rect only creates one rectangle

Question

In an attempt to introduce a particle filter, I first manually drew a rectangle (x, y, w, h) around the car in my image (in red), then I took 50 particles and assigned them noise, i.e. x = x + noise (0.15) and y = y + noise (0.15).

Then I wanted to split all the rectangles for each particle in green, but instead of showing 50 rectangles, it only displays one rectangle.

#include<opencv2\core\core.hpp>
#include<opencv2\imgproc\imgproc.hpp>
#include<opencv2\highgui\highgui.hpp>

#include<stdio.h>
#include<iostream>
#include<random>

using namespace cv;
using namespace std;



const int N = 50;// no of particles

string intToString(int number){

    //this function has a number input and string output
    std::stringstream ss;
    ss << number;
    return ss.str();
}



int main()
{


    Mat frame;
    frame = imread("f (1).png");
    namedWindow("Out");


    //locating the car manually
    Rect car(175, 210, 42, 31);


    //making a rectangle around the car
    rectangle(frame, car, Scalar(0, 0,255), 1, 8, 0);



    //getting tht height and width of the frame
    const int FRAME_HEIGHT = frame.rows;
    const int FRAME_WIDTH = frame.cols;


    //Particle filter initialization

    Mat Init = (Mat_<float>(4, 1) << car.x, car.y, 0, 0);


    //for a gaussian noise distribution
    std::default_random_engine generator;
    std::normal_distribution<double> distribution(0, 15);


    //Initializing the particles
    std::vector<cv::Mat> particle(N, cv::Mat(4, 1, CV_32F));


    cout << car.x << " " << car.y << "\n";

    for (int i = 0; i < N; i++)
    {
        particle[i].at<float>(0, 0) = Init.at<float>(0, 0) + distribution(generator);
        particle[i].at<float>(1, 0) = Init.at<float>(1, 0) + distribution(generator);
        particle[i].at<float>(2, 0) = 0.0;
        particle[i].at<float>(3, 0) = 0.0;
        cout << particle[i] << "\n";
    }

    for (int i = 0; i < N; i++)
    {
        int x = particle[i].at<float>(0, 0);
        int y = particle[i].at<float>(1, 0);

        rectangle(frame, Rect(x, y, 42, 31), Scalar(0, 255, 0), 1, 8, 0);
    }

    imshow("Out", frame);


    waitKey();





    return 0;
}

The result is as follows

The xy particle coordinates are in the following image. The first record is a car that was hardcoded manually, the rest are the coordinates of the particles.

Answer 1

, . :

 //Initializing the particles
    std::vector<cv::Mat> particle(N, cv::Mat(4, 1, CV_32F));

, N Mat, 4 1 float. , , ... ! , Mat ? , Mat . , . . ? , :

template<class T>
vector::vector (size_type n, const value_type& val = value_type(),
                 const allocator_type& alloc = allocator_type()) {
    // how it can be written? Probably in the following way:
    this->resize(n); // allocates using allocator
    for(int i=0;i<n;i++)
         this->innerBuffer[i] = alloc(val); // runs copy constructor with argument val
                    // in our case, this is cv::Mat(const cv::Mat &)
}

cv:: Mat, . , , . Mat:: clone(). clone(). , , Mat , !

, ( , ):

 for (int i = 0; i < N; i++)
    {
        particle[i].at<float>(0, 0) = Init.at<float>(0, 0) + distribution(generator);
        particle[i].at<float>(1, 0) = Init.at<float>(1, 0) + distribution(generator);
        particle[i].at<float>(2, 0) = 0.0;
        particle[i].at<float>(3, 0) = 0.0;
        cout << particle[i] << "\n"; // it is obvius that HERE particles are different
                 // beacuse in the next loop run you overwrite them!
    }

    for (int i = 0; i < N; i++)
    {
        int x = particle[i].at<float>(0, 0);
        int y = particle[i].at<float>(1, 0);

        rectangle(frame, Rect(x, y, 42, 31), Scalar(0, 255, 0), 1, 8, 0);
    }

 for (int i = 0; i < N; i++)
    {
        particle[i].at<float>(0, 0) = Init.at<float>(0, 0) + distribution(generator);
        particle[i].at<float>(1, 0) = Init.at<float>(1, 0) + distribution(generator);
        particle[i].at<float>(2, 0) = 0.0;
        particle[i].at<float>(3, 0) = 0.0;

    }

    for (int i = 0; i < N; i++)
    {
        cout << particle[i] << "\n";

        int x = particle[i].at<float>(0, 0);
        int y = particle[i].at<float>(1, 0);

        rectangle(frame, Rect(x, y, 42, 31), Scalar(0, 255, 0), 1, 8, 0);
    }

, .

: ()

 vector(size_type __n, const value_type& __value,
00199          const allocator_type& __a = allocator_type())
00200       : _Base(__n, __a)
00201       { this->_M_impl._M_finish = std::uninitialized_fill_n(this->
00202                                 _M_impl._M_start,
00203                                 __n, __value); }
00204