title: JavaCV compute ORB descriptors for SIFT keypoints
body: <p>I have big problems calculating ORB descriptors for keypoints found by SIFT detector. If I try to run a simple example program the whole system freezes and I can't figure out why. The sample code is as follows:</p>
  
  <pre><code>import static com.googlecode.javacv.cpp.opencv_highgui.cvLoadImageM;
  
  import com.googlecode.javacv.cpp.opencv_core.CvMat;
  import com.googlecode.javacv.cpp.opencv_features2d.DescriptorExtractor;
  import com.googlecode.javacv.cpp.opencv_features2d.FeatureDetector;
  import com.googlecode.javacv.cpp.opencv_features2d.KeyPoint;
  import com.googlecode.javacv.cpp.opencv_features2d.ORB;
  import com.googlecode.javacv.cpp.opencv_nonfree.SIFT;
  
  public class DescriptorTest {
  
      public static void main(String[] args) {
          SIFT sift = new SIFT(0, 3, 0.04, 10, 1.6);
          FeatureDetector detector = sift.getFeatureDetector();
          ORB orb_descriptor = new ORB(500, 1.2f, 8, 31, 0, 2, 0, 31);
          DescriptorExtractor descriptor = orb_descriptor.getDescriptorExtractor();        
          CvMat image = cvLoadImageM("res/dvd_009_ref.jpg");
          KeyPoint keypoints = new KeyPoint();
          CvMat descriptors = new CvMat(null);
          detector.detect(image, keypoints, null);
          System.out.println("Keypoints found: "+ keypoints.capacity());
          descriptor.compute(image, keypoints, descriptors);
          System.out.println("Descriptors calculated: "+descriptors.rows());
      }
  }
  </code></pre>
  
  <p>Does anyone has an idea what the problem is? Would be great :)</p>