  Recent advances in generative adversarial networks (GANs) have demonstrated
the capabilities of generating stunning photo-realistic portrait images. While
some prior works have applied such image GANs to unconditional 2D portrait
video generation and static 3D portrait synthesis, there are few works
successfully extending GANs for generating 3D-aware portrait videos. In this
work, we propose PV3D, the first generative framework that can synthesize
multi-view consistent portrait videos. Specifically, our method extends the
recent static 3D-aware image GAN to the video domain by generalizing the 3D
implicit neural representation to model the spatio-temporal space. To introduce
motion dynamics to the generation process, we develop a motion generator by
stacking multiple motion layers to generate motion features via modulated
convolution. To alleviate motion ambiguities caused by camera/human motions, we
propose a simple yet effective camera condition strategy for PV3D, enabling
both temporal and multi-view consistent video generation. Moreover, PV3D
introduces two discriminators for regularizing the spatial and temporal domains
to ensure the plausibility of the generated portrait videos. These elaborated
designs enable PV3D to generate 3D-aware motion-plausible portrait videos with
high-quality appearance and geometry, significantly outperforming prior works.
As a result, PV3D is able to support many downstream applications such as
animating static portraits and view-consistent video motion editing. Code and
models are released at https://showlab.github.io/pv3d.
