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FacemarkLBF Params model_filename error

asked 2018-10-02 04:29:09 -0500

burstasia gravatar image

updated 2018-10-02 04:44:14 -0500

berak gravatar image

Hi there OpenCv community!

I'm brand new to OpenCV and I've been trying to build a real time face tracking app using Landmark (from the OpenCV contrib)

And when I try to create my facemark ptr, I give it a FacemarkLBF::Params variable. The issue is that the model_filename variable in the Params struct has an error of "Error reading characters of string" when I create the params. Therefore if I try to access the model_filename the program crashes with a read access violation error.

Is this a known issue? I am using OpenCV 3.4.3 and the latest version of the OpenCV contrib from Github.

Here is the code:

    //create instance of lbf facemark model
cv::face::FacemarkLBF::Params params{};
params.n_landmarks = 68; // number of landmark points
params.initShape_n = 10; // number of multiplier for make data augmentation
params.stages_n = 5; // amount of refinement stages
params.tree_n = 6; // number of tree in the model for each landmark point
params.tree_depth = 5; //he depth of decision tree
std::string name{ "lbfmodel.yaml" };
params.model_filename = name.c_str(); //path name to saved lbf facemark model
cv::Ptr<cv::face::Facemark> facemark = cv::face::FacemarkLBF::create(params);

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Done, replaced the image with text! :)

burstasia gravatar imageburstasia ( 2018-10-02 04:44:46 -0500 )edit

thanks for the edit !

did you really want to train a new model ? (else you don't need the "Params" at all)

berak gravatar imageberak ( 2018-10-02 04:45:03 -0500 )edit

Nope, the lbfmodel is trained I believe. So I'm just trying to use the trained model to create the landmarks on the face

burstasia gravatar imageburstasia ( 2018-10-02 04:47:08 -0500 )edit

As far as I understand I need the parameters to create the facemark variable?

burstasia gravatar imageburstasia ( 2018-10-02 04:50:03 -0500 )edit

no, you can use createFacemarkLBF() without params.

berak gravatar imageberak ( 2018-10-02 05:08:43 -0500 )edit

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answered 2018-10-02 04:58:38 -0500

berak gravatar image

updated 2018-10-02 05:02:51 -0500

then use code like this:

Ptr<face::Facemark> facemark = face::createFacemarkLBF();
facemark->loadModel("C:\\data\\mdl\\lbfmodel.yaml");  // <-- change path !

CascadeClassifier cascade("C:\\data\\mdl\\haarcascade_frontalface_alt2.xml"); // <-- here,too!
Mat image = imread("david2.jpg");  // your image here !

vector<Rect> faces;

vector<vector<Point2f>> fits;
bool ok = facemark->fit(image, faces, fits);
cout << ok << " " << fits.size() << endl;
for (int p=0; p<fits.size(); p++) { // persons
    for (int i=0; i<68; i++) { // points
        circle(image, fits[p][i], 3, Scalar(200,0,0), 2);

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Thank you so much for your answer, I'm going to test it out now! I'm somewhat surprised that you need absolute paths?

burstasia gravatar imageburstasia ( 2018-10-02 05:43:47 -0500 )edit

no, probably not nessecary, it's just the way i had it on my disk ..

berak gravatar imageberak ( 2018-10-02 05:45:21 -0500 )edit

Ah okay, is there a way I can DM you? Because I'm running into another issue and I don't think it belongs on this thread

burstasia gravatar imageburstasia ( 2018-10-02 05:52:26 -0500 )edit

To anyone checking this in the future, make sure you're using the same version for opencv and opencv_contrib! That was my main issue

burstasia gravatar imageburstasia ( 2018-10-02 07:41:31 -0500 )edit
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Asked: 2018-10-02 04:29:09 -0500

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Last updated: Oct 02 '18