Mat to CvMat conversion problem (Bug #3413)

Could you please elaborate on your problem. Please supply the code that generates the error.
Because reading through Java documentation (http://docs.opencv.org/java/) I noticed that it should be possible with simple conversion operators:

_
Partial yet very common cases of this user-allocated data case are conversions from CvMat and IplImage to Mat. For this purpose, there are special constructors taking pointers to CvMat or IplImage and the optional flag indicating whether to copy the data or not.

Backward conversion from Mat to CvMat or IplImage is provided via cast operators Mat.operator CvMat() const and Mat.operator IplImage(). The operators do NOT copy the data.

// C++ code:

IplImage* img = cvLoadImage("greatwave.jpg", 1);

Mat mtx(img); // convert IplImage* -> Mat

CvMat oldmat = mtx; // convert Mat -> CvMat

CV_Assert(oldmat.cols img->width && oldmat.rows img->height &&

oldmat.data.ptr (uchar*)img->imageData && oldmat.step img->widthStep);

Use MATLAB-style array initializers, zeros(), ones(), eye(), for example:

// C++ code:

// create a double-precision identity martix and add it to M.

M += Mat.eye(M.rows, M.cols, CV_64F);

Use a comma-separated initializer:

// C++ code:

// create a 3x3 double-precision identity matrix

Mat M = (Mat_(3,3) << 1, 0, 0, 0, 1, 0, 0, 0, 1);_

Steven Puttemans wrote:

Could you please elaborate on your problem. Please supply the code that generates the error.
Because reading through Java documentation (http://docs.opencv.org/java/) I noticed that it should be possible with simple conversion operators:

The code generating the problem is really basic, but here is the full code with all the nessesary imports. I really have no idea why this occures. Maybe you guys can find the glitch?

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.*;
import java.io.File;
import java.io.IOException;
import java.util.StringTokenizer;
import java.util.Vector;

import com.googlecode.javacpp.*;
import com.googlecode.javacv.*;
import com.googlecode.javacv.cpp.opencv_core.CvMat;
import com.googlecode.javacv.cpp.opencv_core.CvTermCriteria;
import com.googlecode.javacv.cpp.opencv_core.IplImage;
import com.googlecode.javacv.cpp.opencv_core.Ptr;
import com.googlecode.javacv.cpp.opencv_features2d.BOWKMeansTrainer;
import com.googlecode.javacv.cpp.opencv_flann.KMeansIndexParams;
import com.googlecode.javacv.cpp.opencv_nonfree.SIFT;

import org.opencv.*;
import org.opencv.highgui.*;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.MatOfKeyPoint;
import org.opencv.core.Scalar;
import org.opencv.core.TermCriteria;
import org.opencv.features2d.DescriptorExtractor;
import org.opencv.features2d.FeatureDetector;
import org.opencv.features2d.Features2d;
import org.opencv.features2d.KeyPoint;

import javax.imageio.ImageIO;
import javax.swing.SwingUtilities;

public class Tracker {

    public static void main(String args[]) throws IOException{

        File tmp = new File("opencv_java247.dll");
        System.load(tmp.getAbsolutePath());

        String url = "test.jpg";

        File f = new File(url);
        BufferedImage buf = ImageIO.read(f);        

        Mat input = Highgui.imread(url, Highgui.CV_LOAD_IMAGE_GRAYSCALE);
        Mat desc = new Mat(), out = Highgui.imread(url, Highgui.CV_LOAD_IMAGE_UNCHANGED);
        //input.put(0, 0, ((DataBufferByte) buf.getRaster().getDataBuffer()).getData());
        MatOfKeyPoint keypoints = new MatOfKeyPoint();
        DescriptorExtractor detector = DescriptorExtractor.create(DescriptorExtractor.SIFT);
        FeatureDetector ft = FeatureDetector.create(FeatureDetector.SIFT);

        ft.detect(out, keypoints);
        detector.compute(input, keypoints, desc);
        Features2d.drawKeypoints(input, keypoints, out, new Scalar(255,0,0), 4);
        Highgui.imwrite("test3.jpg", out);

        CvMat zonk = desc; //<== the error is here
        zonk.put(0, 0);
        int size = 3, ret = 1;
        CvTermCriteria tc = new CvTermCriteria(TermCriteria.MAX_ITER, 50, 0.001);

        BOWKMeansTrainer bt = new BOWKMeansTrainer(size, tc, ret, Core.KMEANS_PP_CENTERS);
        CvMat dict = bt.cluster(zonk);
    }
}

It's a bit messy, but I've tried to get it going in many different ways.

Ok, thanks anyway.