Question

我正在尝试使用Android进行面部识别。所有负载都可以，但是 haarcascade_frontalface_alt2.xml 文件，我不知道如何使用JavaCV加载它。这是我的代码：

public static void detectFacialFeatures()
{
    // The cascade definition to be used for detection.

    // This will redirect the OpenCV errors to the Java console to give you
    // feedback about any problems that may occur.
    new JavaCvErrorCallback();

    // Load the original image.

    // We need a grayscale image in order to do the recognition, so we
    // create a new image of the same size as the original one.
    IplImage grayImage = IplImage.create(iplImage.width(),iplImage.height(), IPL_DEPTH_8U, 1);

    // We convert the original image to grayscale.
    cvCvtColor(iplImage, grayImage, CV_BGR2GRAY);

    CvMemStorage storage = CvMemStorage.create();

    // We instantiate a classifier cascade to be used for detection, using the cascade definition.
    CvHaarClassifierCascade cascade = new CvHaarClassifierCascade(cvLoad("./haarcascade_frontalface_alt2.xml"));

    // We detect the faces.
    CvSeq faces = cvHaarDetectObjects(grayImage, cascade, storage, 1.1, 1, 0);

    Log.d("CARAS","Hay "+faces.total()+" caras ahora mismo");
}

问题出在这里

CvHaarClassifierCascade（cvLoad（ “./ haarcascade_frontalface_alt2.xml”））;

我已经尝试将xml文件放入/ assets文件夹，但我不知道如何加载它。它总是给我下一个错误：

03-26 17:31:25.385: E/cv::error()(14787): OpenCV Error: Null pointer (Invalid classifier cascade) in CvSeq* cvHaarDetectObjectsForROC(const CvArr*, CvHaarClassifierCascade*, CvMemStorage*, std::vector<int>&, std::vector<double>&, double, int, int, CvSize, CvSize, bool), file /home/saudet/projects/cppjars/OpenCV-2.4.4/modules/objdetect/src/haar.cpp, line 1514

... 看起来更接近它指向此代码行的错误：

CvSeq faces = cvHaarDetectObjects（grayImage，cascade，storage，1.1,1， 0）;

这就是我很确定问题来自haarcascade_frontalface_alt2.xml加载的原因。

感谢您的帮助。

P.D：我想将级联包含在apk中而不是sdcard中。

Answer 1

如果您的级联在SD卡中，您可以使用：

CascadeClassifier cascade = new CascadeClassifier(Environment.getExternalStorageDirectory().getAbsolutePath() + "/cascade.xml");

Environment.getExternalStorageDirectory().getAbsolutePath()为您提供正确的SD卡路径，然后是SD卡中的文件地址。

Answer 2

您可以将文件打包到apk中，然后将其复制到外部位置，以便OpenCV函数可以访问它。

    try {
        File learnedInputFile = new File(Environment.getExternalStorageDirectory().getPath() + "/learnedData.xml");
        if (!learnedInputFile.exists()) {
            InputStream learnedDataInputStream = assetManager.open("learnedData.xml");
            FileOutputStream learnedDataOutputStream = new FileOutputStream(learnedInputFile);

            // copy file from asset folder to external location, i.e. sdcard
            byte[] buffer = new byte[300];
            int n = 0;
            while (-1 != (n = learnedDataInputStream.read(buffer))) {
                learnedDataOutputStream.write(buffer, 0, n);
            }
        }
        classifier.load(learnedInputFile.getAbsolutePath());
    } catch (IOException exception) {
        // there are no learned data, train ml algorithm or show error, etc.
    }

如何使用JavaCV在Android中加载ClassifierCascade？

2 个答案: