OpenCV (CvHaarClassifierCascade*) cvLoad doesn't load, unable to load xml file

Question

I\'m trying face detection using OpenCv 2.3. My trying to load "haarcascade_frontalface_alt_tree.xml" on my project, I\'m constantly unable to load the xml file.

Answer 1

To narrow down the issue, before calling cvLoad you should check to see if the file exists. Here's one way:

struct stat buf;
int statResult = stat(file,&buf);
if (statResult || buf.st_ino < 0) {
    cout << "File not found: " << file << endl;
    exit(-2);
}

You'll need to #include

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On my system (OS X 10.6.8/OpenCV 2.3), when I attempt to load haarcascade_frontalface_alt_tree.xml or haarcascade_frontalface_alt.xml I get an exception:

OpenCV Error: Unspecified error (The node does not represent a user object (unknown type?)) in cvRead, file /Users/steve/Development/opencv2/opencv/modules/core/src/persistence.cpp, line 4857

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I think you are using an outdated OpenCV 1 tutorial that doesn't work with the current version of haarcascade_frontalface_alt_tree.xml. Try this OpenCV 2 tutorial instead. This code from that tutorial works for me:

CascadeClassifier face_cascade;
if (!face_cascade.load( file) ) { 
    cout << "Couldn't load face_cascade" << endl;
    exit(-1); 
}

cout << "Loaded face_cascade" << endl;