How to manipulate dlib landmark points

Question

I wonder how can I manipulate/access the dlib landmark points. I run the code on the camera preview with the intention of detecting some particular emotions. I would like to check how for example the distance between eyelids or how the position of the lips changes in time and so on.

Answer 1

For python api - try this link (https://matthewearl.github.io/2015/07/28/switching-eds-with-python/)

For C++ - http://dlib.net/train_shape_predictor_ex.cpp.html sample has code for estimating interocular distance:

double interocular_distance (
    const full_object_detection& det
)
{
    dlib::vector<double,2> l, r;
    double cnt = 0;
    // Find the center of the left eye by averaging the points around 
    // the eye.
    for (unsigned long i = 36; i <= 41; ++i) 
    {
        l += det.part(i);
        ++cnt;
    }
    l /= cnt;

    // Find the center of the right eye by averaging the points around 
    // the eye.
    cnt = 0;
    for (unsigned long i = 42; i <= 47; ++i) 
    {
        r += det.part(i);
        ++cnt;
    }
    r /= cnt;

    // Now return the distance between the centers of the eyes
    return length(l-r);
}

Same way you can access any facial features More info about the feature numbers can be found in dlib/image_processing/render_face_detections.h