Question

I’m just now starting to learn how to use the openCV libraries. I’ve downloaded and installed openCV 2.4.0, and have run a few example projects. In this block of code, I’m trying to get the output from goodFeaturesToTrack and plot the points on an image. The code compiles, but every time I run it, it crashes, and I get the following error:

---

Windows has triggered a breakpoint in Corner.exe.

This may be due to a corruption of the heap, which indicates a bug in Corner.exe or any of the DLLs it has loaded.

This may also be due to the user pressing F12 while Corner.exe has focus.

The output window may have more diagnostic information.

---

The output window does not have more diagnostic information. I’ve traced the error to the goodFeaturesToTrack function. Here’s the offending code:

// Corner.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <opencv.hpp>
#include <opencv_modules.hpp>
#include <opencv2\core\core.hpp>
#include <opencv2\highgui\highgui.hpp>

#include <iostream>
#include <string>
#include <iomanip>
#include <sstream>

using namespace cv; //If you don't have this, you won't be able to create a mat...
using namespace std;


#include <stdio.h>
#include <cv.h>
#include <highgui.h>
#include <math.h>

//Whole bunch of #defines to make editing the code a lot easier

#define MAX_FEATURES 5
#define FILENAME "C:/Users/Mitchell/Desktop/lol.jpg"

int main(void)
{
    namedWindow("Out", CV_WINDOW_AUTOSIZE);
    namedWindow("In", CV_WINDOW_AUTOSIZE);  
    Mat Img;
    Img = cvLoadImage(FILENAME, CV_LOAD_IMAGE_GRAYSCALE);

    if(!Img.data)
    {
        fprintf(stderr, "ERROR: Couldn't open picture.");
        waitKey();
        return -1;
    }

    else
    {
        imshow("In", Img);
        waitKey();
    }

    std::vector<cv::Point2f> Img_features;
    int number_of_features = MAX_FEATURES;

    Mat Out = Mat::zeros(Img.cols, Img.rows, CV_32F);

    goodFeaturesToTrack(Img, Img_features, MAX_FEATURES, .01, .1, noArray(), 3, false);

    fprintf(stdout, "Got here...");

    /*for (int i = 0; i < MAX_FEATURES; i++)
    {
        Point2f p = Img_features[i];
        ellipse(Img, p, Size(1,1), 0, 0, 360, Scalar(255,0,0));
    }*/

    imshow("Out", Out);

    waitKey(0);
    return 0;


}

Is this a bug in the library, or am I doing something dumb?

Answer 1

May be Img_features vector should have MAX_FEATURES items before calling goodFeatures? i.e. try Img_features.resize(MAX_FEATURES) before goodFeatures call.