Error first OPENCV project on Raspberry Pi 2

[Miguel Lopez]

Hello.

I'm trying to run Opencv on raspberry and i can't... In Windows, I work with Qt and OpenCv without problems, but in Raspberry appears an error with all funtions:

My code is:

temporal.pro:

   QT       += core gui

   greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

   TARGET = temporal
   TEMPLATE = app

    SOURCES += main.cpp\
    mainwindow.cpp

    HEADERS  += mainwindow.h

    FORMS    += mainwindow.ui

    INCLUDEPATH +=/usr/local/include
    LIBS += -L/usr/local/lib -lopencv_core -lopencv_imgcodecs -lopencv_highgui

mainwindow.h:

    #ifndef MAINWINDOW_H
    #define MAINWINDOW_H
    #include <opencv2/core/core.hpp>
    #include <opencv2/highgui/highgui.hpp>
    #include <opencv2/imgproc/imgproc.hpp>
    #include <QMainWindow>
    #include <iostream>
    #include <stdio.h>
    #include <stdlib.h>

    namespace Ui {
    class MainWindow;
    }

    class MainWindow : public QMainWindow
    {
        Q_OBJECT

    public:
        explicit MainWindow(QWidget *parent = 0);
        ~MainWindow();

    private slots:
        void on_pushButton_clicked();

    private:
        Ui::MainWindow *ui;
    };

    #endif // MAINWINDOW_H

main.cpp:

    #include "mainwindow.h"
    #include <QApplication>

    int main(int argc, char *argv[])
    {
        QApplication a(argc, argv);
        MainWindow w;
        w.show();
    }

mainwindow.cpp:

    #include "mainwindow.h"
    #include "ui_mainwindow.h"

    #include <opencv2/highgui/highgui.hpp>

    using namespace cv;

    MainWindow::MainWindow(QWidget *parent) :
        QMainWindow(parent),
        ui(new Ui::MainWindow)
    {
        ui->setupUi(this);
    }

    MainWindow::~MainWindow()
    {
        delete ui;
    }

    void MainWindow::on_pushButton_clicked()
    {
        Mat img = imread("/home/pi/test.png",1);
    }

I make test and the problem appears when i write the function, in this case, imread. And the error is:

mainwindow.o: undefined reference to symbol '_ZN2cv6String10deallocateEv'
error adding symbols: DSO missing from command line
collect2: error: Id returned 1 exit status

Any idea??

Many thanks!!!

[SGaist]

Hi and welcome to devnet,

Are you building directly on the Pi2 ?

[Miguel Lopez]

@SGaist Yes, I make this project on Qt in Raspberry. I installed opencv following this video: https://youtu.be/rEaQqZ7VM70

[SGaist]

Looks like for some reason there's a symbol from opencv_core that is not found. Can you try to build a basic main.cpp only using OpenCV ?