  Portrait synthesis creates realistic digital avatars which enable users to
interact with others in a compelling way. Recent advances in StyleGAN and its
extensions have shown promising results in synthesizing photorealistic and
accurate reconstruction of human faces. However, previous methods often focus
on frontal face synthesis and most methods are not able to handle large head
rotations due to the training data distribution of StyleGAN. In this work, our
goal is to take as input a monocular video of a face, and create an editable
dynamic portrait able to handle extreme head poses. The user can create novel
viewpoints, edit the appearance, and animate the face. Our method utilizes
pivotal tuning inversion (PTI) to learn a personalized video prior from a
monocular video sequence. Then we can input pose and expression coefficients to
MLPs and manipulate the latent vectors to synthesize different viewpoints and
expressions of the subject. We also propose novel loss functions to further
disentangle pose and expression in the latent space. Our algorithm shows much
better performance over previous approaches on monocular video datasets, and it
is also capable of running in real-time at 54 FPS on an RTX 3080.
