Maltergate's profile - activity

Up :) I'd like to understand too. I get these via Arucos however I don't see what it refers to. To my understanding :

• tvecs is the location vector (stored in a 3X1 matrix), the coordinates x,y,z of the chessboard or aruco in camera's coordinates system, which is z along optical axis, x to the right and y to the bottom)
  • rvecs is the rotation vector (same as above) of the aruco under camera's coordinates system (same as above).

However it seems that I'm missing something there. When I print the values of rvecs with :

rvecs[i].at<double>(0,k)

Well it seems that values are correlated...

Hi @berak,

Thanks for your awnser. I'll redesign my program in order to avoid multi-threading then. The HighGUI will be used in main thread and I'll create a thread for mat processing (finding the edges, calculating new trajectory, etc...)

However if you have further information why this (highgui in another thread) cannot work, i'd be happy to read it. In fact I really don't understand why, what's the difference between two threads, why it would work in the first one and not in the second.

Hi dears,

First of all, thanks for your time :).

I'm trying to create thread (yes I know, multi-thread is bad however I'd like to experiment) in which I would display an image.

I have read OpenCV doesn't handle very much the threading and for some people, the window creation has to be done in main thread. So that's what I did.

int main(int argc, const char * argv[]) {

    bool success(true), ihm_run(true);

    Drone_Controller drone;
    Vision_Manager vision(drone);

    success = drone.connect();
    if (!success)
        return EXIT_FAILURE;

    cv::namedWindow("Display & Command", CV_WINDOW_AUTOSIZE);

    drone.enable_video_stream();
    vision.ihm_start(&ihm_run);

    while (ihm_run)
    {
        if (ihm.get_key_pressed == 27)
        {
            ihm_run = false;
        }
    }
    vision.stop_ihm();
}

Now I have a class named Vision_manager with the following vision_manager.h :

class Vision_Manager {

public:

/* ------ CONSTRUCTEUR & DESTRUCTEUR ------ */
Vision_Manager(Drone_Controller& drone);
~Vision_Manager();

/* ------ FONCTIONS MEMBRES UTILISABLES DANS LE MAIN ------ */
void video_controls(); //Affiche la vidéo et récupère les entrées clavier
char get_key_pressed();
void ihm_start(bool *m_IHMRun);
void ihm_stop();

private:

/* ------ ATTRIBUTS ------ */
Drone_Controller& m_drone;
cv::Mat m_picture_rgb;
char m_key_pressed;

bool *m_IHMRun;

//Déclaration du thread utilisé pour l'ihm
std::thread m_ihm_thread;
};

and vision_manager.c :

#include "vision_manager.hpp"

Vision_Manager::Vision_Manager(Drone_Controller& drone) : m_drone(drone)
{

}

Vision_Manager::~Vision_Manager()
{
    cv::destroyAllWindows();
}

void Vision_Manager::ihm_start(bool *IHMRun)
{
    m_ihm_thread = std::thread(&Vision_Manager::video_controls, this);
    //&Vision_Manager::video_controls, this, N

    m_IHMRun = IHMRun;
}

void Vision_Manager::ihm_stop()
{
    m_ihm_thread.join();

    std::cout << "Jointure effectuée" << std::endl;
}

void Vision_Manager::video_controls()
{
    int picture_nb;

    //Créationde la fenêtre
    //cv::namedWindow("Affichage & Commandes", CV_WINDOW_AUTOSIZE);

    picture_nb = m_drone.get_picture_nb();

    while (*m_IHMRun == true)
    {
        // Si l'initialitasion du stream n'a pas plantée et que l'image qu'on récupère est différente de celle d'avant
        if (m_drone.get_picture_nb() != picture_nb)
        {
            // On récupère l'image
            m_picture_rgb = m_drone.get_picture();
            picture_nb = m_drone.get_picture_nb();

            // Test si l'image a bien été récupérée
            if (m_picture_rgb.empty())
            {
                //Si elle est vide ça ne sert à rien (typiquement en début de programme)
                std::cout << "Image vide \n";
            }
            else
            {
                //Affichage de l'image avec le niveau de batterie
                cv::imshow("Affichage & Commandes", m_picture_rgb);
                std::cout << "ImShow OpenCV" << std::endl;
            }
        }

        m_key_pressed = cv::waitKey(50);
    }

    cv::destroyWindow("Affichage & Commandes");
}

char Vision_Manager::get_key_pressed()
{
    return m_key_pressed;
}

Everything is compiling and the thread is created as I see the prompts. However I do not have any window.

Does anyone know ?

Thanks again for your help :).