How to load ClassifierCascade in Android using JavaCV? - opencv

Question

I'm trying to use facial recognition with Android . All the loads are ok , but the haarcascade_frontalface_alt2.xml file wich i don't know how to load it using JavaCV.
This is the code i have:
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");
}
The problem is here
CvHaarClassifierCascade(cvLoad("./haarcascade_frontalface_alt2.xml"));
I have tried putting the xml file it into the /assets folder , but i have no idea of how must i load it. It's always giving me the next error:
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
...
looking more near at the error it points to this code line:
CvSeq faces = cvHaarDetectObjects(grayImage, cascade, storage, 1.1, 1,
0);
That's why i'm pretty sure that the problem comes from the haarcascade_frontalface_alt2.xml load.
Thanks for your help.
P.D: I want to include the cascade into the apk not in sdcard .

Answer 1

If your cascade is in SD card you can use:
CascadeClassifier cascade = new CascadeClassifier(Environment.getExternalStorageDirectory().getAbsolutePath() + "/cascade.xml");
Environment.getExternalStorageDirectory().getAbsolutePath() give you right path to SD card and next - is address to your file in your SD.

Answer 2

You can pack your file in apk and then copy it to external location so it is accessible by OpenCV functions.
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.
}