Converting Mat to Keypoint?

Question

I\'m writing both descriptors (SurfDescriptorExtractor output) and keypoints (SurfFeatureDetector output) to an XML file. Before writing keypoints (std::vector) conversion to Ma

Answer 1

This is how the opencv source code does the conversion in Java, I couldn't find this conversion in C++, it might not exist. You might be able to translate this to C++, it is not very complex.

 //Code from Opencv4Android: utils/Converters.java
 public static void Mat_to_vector_KeyPoint(Mat m, List kps) {
        if (kps == null)
            throw new java.lang.IllegalArgumentException("Output List can't be null");

        int count = m.rows();
        if (CvType.CV_64FC(7) != m.type() || m.cols() != 1)
            throw new java.lang.IllegalArgumentException(
                    "CvType.CV_64FC(7) != m.type() ||  m.cols()!=1\n" + m);

        kps.clear();
        double[] buff = new double[7 * count];
        m.get(0, 0, buff);

        for (int i = 0; i < count; i++) {
            kps.add(new KeyPoint((float) buff[7 * i], (float) buff[7 * i + 1], (float) buff[7 * i + 2], (float) buff[7 * i + 3],
                    (float) buff[7 * i + 4], (int) buff[7 * i + 5], (int) buff[7 * i + 6]));
        }
    }