  We introduce GaussianAvatars, a new method to create photorealistic head
avatars that are fully controllable in terms of expression, pose, and
viewpoint. The core idea is a dynamic 3D representation based on 3D Gaussian
splats that are rigged to a parametric morphable face model. This combination
facilitates photorealistic rendering while allowing for precise animation
control via the underlying parametric model, e.g., through expression transfer
from a driving sequence or by manually changing the morphable model parameters.
We parameterize each splat by a local coordinate frame of a triangle and
optimize for explicit displacement offset to obtain a more accurate geometric
representation. During avatar reconstruction, we jointly optimize for the
morphable model parameters and Gaussian splat parameters in an end-to-end
fashion. We demonstrate the animation capabilities of our photorealistic avatar
in several challenging scenarios. For instance, we show reenactments from a
driving video, where our method outperforms existing works by a significant
margin.
