  As recent advances in Neural Radiance Fields (NeRF) have enabled
high-fidelity 3D face reconstruction and novel view synthesis, its manipulation
also became an essential task in 3D vision. However, existing manipulation
methods require extensive human labor, such as a user-provided semantic mask
and manual attribute search unsuitable for non-expert users. Instead, our
approach is designed to require a single text to manipulate a face
reconstructed with NeRF. To do so, we first train a scene manipulator, a latent
code-conditional deformable NeRF, over a dynamic scene to control a face
deformation using the latent code. However, representing a scene deformation
with a single latent code is unfavorable for compositing local deformations
observed in different instances. As so, our proposed Position-conditional
Anchor Compositor (PAC) learns to represent a manipulated scene with spatially
varying latent codes. Their renderings with the scene manipulator are then
optimized to yield high cosine similarity to a target text in CLIP embedding
space for text-driven manipulation. To the best of our knowledge, our approach
is the first to address the text-driven manipulation of a face reconstructed
with NeRF. Extensive results, comparisons, and ablation studies demonstrate the
effectiveness of our approach.
