OpenCV 2.4.8 warpPerspective error

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I'm getting error on my source, and can't find the reason.

Debug Assertion Failed! File : f:\dd\vctools\crt_bld\self_x86\crt\src\dbgheap.c Line : 1322 Expression : _CrtIsValidHeapPointer(pUserData)

Looks like this is kind of memory error, but I don't know why this is happening. I made a source very similar to source in here. http://ift.tt/1pY7hM2

int main()
{
    int n;
    cout << "numbers of images : ";
    cin >> n;

    char file_input[30][256] = {0,}, file_output[30][256] = {0,};
    Mat img[30];
    Mat img_output[30];

    for(int i=0; i<n+1; i++)    // file name
    {
        sprintf(file_input[i], "d%d.jpg", i+1);
        sprintf(file_output[i], "OUTPUT%d.jpg", i);
        img[i] = imread(file_input[i], CV_LOAD_IMAGE_GRAYSCALE);
    }

    int minHessian = 400;
    SurfFeatureDetector detector(minHessian);

    vector<KeyPoint> keypoints_object;
    vector<KeyPoint> keypoints_scene;

    detector.detect(img[0], keypoints_object);

    SurfDescriptorExtractor extractor;
    Mat descriptors_object;
    Mat descriptors_scene;

    extractor.compute(img[0], keypoints_object, descriptors_object);

    FlannBasedMatcher matcher;
    vector<DMatch> matches;
    vector<DMatch> good_matches;

    for(int i=1; i<n; i++)
    {
        keypoints_scene.clear();
        matches.clear();
        good_matches.clear();

        detector.detect(img[i], keypoints_scene);
        extractor.compute(img[i], keypoints_scene, descriptors_scene);

        matcher.match(descriptors_object, descriptors_scene, matches);
        double max_dist = 0;
        double min_dist = 100;
        for(int j=0; j<descriptors_object.rows; j++)
        {
            double dist = matches[j].distance;
            if(dist < min_dist) min_dist = dist;
            if(dist > max_dist) max_dist = dist;
        }

        for(int j=0; j<descriptors_object.rows; j++)
        {
            if(matches[j].distance < 3*min_dist)
                good_matches.push_back(matches[j]);
        }

        vector<Point2f> obj;
        obj.clear();
        vector<Point2f> scene;
        scene.clear();

        for(int j=0; j<good_matches.size(); j++)
        {
            obj.push_back(keypoints_object[good_matches[i].queryIdx].pt);
            scene.push_back(keypoints_scene[good_matches[i].trainIdx].pt);
        }

        Mat H = findHomography(obj, scene, CV_RANSAC);

        warpPerspective(img[i], img_output[i], H, Size(img[0].cols, img[0].rows));
        imwrite(file_output[i], img_output[i]);
    }
    return 0;
}

My input is file "d1.jpg", "d2.jpg", "d3.jpg" and n=3. those pictures are photo of same paper, but is taken on little different angle (within 5 degrees?).

I want to match the images "d2.jpg" and "d3.jpg" on "d1.jpg" exactly, so I used warpPerspective to do so. but the problem occurs, and also the output image is nothing but GRAY, which is NOT what I expected.

Please help. (I apologize for bad English and bad explanation)

asked 1 min ago

user3799624

1