1. First compile the C++ models to be able to extract the features
2. Extract features using scripts in the "data extraction" folder, this allows to build a PCA subspace for HOGs that is relevant to faces and facial expressions
    - run all of the extract_features_*.m scripts 
    - this will take some time: 4-20 hours depending on your machine as you will need to process a lot of visual data
    - you need to make sure you have the right datasets and they are in the right locations
    - Note for Bosphorus you will need to change the code a bit and add face_model.Reset(); after frame_count++ line in FeatureExtraction.cpp (this is because the images are not from a video and are quite far from each other).

Create a PCA model