android - OpenCV 2.4.5 android, FeatureDetector, DescriptorExtractor

Question

使用 OpenCV-2.4.5-android-sdk，我尝试通过特征检测(ORB 检测器和汉明匹配器)来匹配两张图像。不幸的是，在计算描述符时我总是得到 NullPointerException。我究竟做错了什么？

        FeatureDetector detector = FeatureDetector.create("ORB");
        DescriptorExtractor descriptor = DescriptorExtractor.create("ORB");
        BFMatcher matcher = new BFMatcher(Hamming.normType, true);

        KeyPoint keypoints1 = new KeyPoint();
        KeyPoint keypoints2 = new KeyPoint();
        CvMat[] descriptors = new CvMat[2];

        //ORB orb = new ORB();

        //orb.detect(image1, null, keypoints1);
        detector.detect(image1, keypoints1, null);
        descriptor.compute(image1, keypoints1, descriptors[0]);

        detector.detect(image2, keypoints2, null);
        //orb.detect(image2, null, keypoints2);
        descriptor.compute(image2, keypoints2, descriptors[1]);

        // matcher should include 2 different image's descriptors
        DMatch matches = new DMatch();
        matcher.match(descriptors[0], descriptors[1], matches, null);

我想知道，如果我有一个更改，可以在没有 android-ndk 的情况下使用 openCV 在 Android 上执行特征检测。您会建议尝试编写和集成 native C++ 代码吗？

更新:重组项目设置后，执行以下操作:http://docs.opencv.org/trunk/doc/tutorials/introduction/android_binary_package/dev_with_OCV_on_Android.html#dev-with-ocv-on-android描述，代码如下所示:

    FeatureDetector detector = FeatureDetector.create(FeatureDetector.ORB);
    DescriptorExtractor descriptor = DescriptorExtractor.create(DescriptorExtractor.ORB);
    DescriptorMatcher matcher = DescriptorMatcher.create(DescriptorMatcher.BRUTEFORCE_HAMMING);

    MatOfKeyPoint keypoints1 = new MatOfKeyPoint();
    MatOfKeyPoint keypoints2 = new MatOfKeyPoint();
    Mat[] descriptors = new Mat[2];

    //ORB orb = new ORB();
    //orb.detect(image1, null, keypoints1);
    detector.detect(image1, keypoints1, null);
    descriptor.compute(image1, keypoints1, descriptors[0]);

    detector.detect(image2, keypoints2, null);
    //orb.detect(image2, null, keypoints2);
    descriptor.compute(image2, keypoints2, descriptors[1]);

    // matcher should include 2 different image's descriptors
    MatOfDMatch matches = new MatOfDMatch();
    matcher.match(descriptors[0], descriptors[1], matches);

NPE 仍然会发生。

Answer 1

您似乎错过了将对象分配给 descriptors[] 数组。

    descriptors[0] = new CvMat();
    descriptors[1] = new CvMat();