Please see the following blog post for more details about this code

Face Reconstruction using EigenFaces (C++/Python)

To train your own model

1. Download images. These images are the first 1000 images of the CelebA dataset. You can create a larger model by using more aligned and cropped images from the CelebA dataset.
2. Use createPCAModel.cpp or createPCAModel.py to create the modelfile pcaParams.yml.
3. Use reconstructFace.cpp or reconstructFace.py to reconstruct the face. It needs the pcaParams.yml file.