  Recent communities have seen significant progress in building photo-realistic
animatable avatars from sparse multi-view videos. However, current workflows
struggle to render realistic garment dynamics for loose-fitting characters as
they predominantly rely on naked body models for human modeling while leaving
the garment part un-modeled. This is mainly due to that the deformations
yielded by loose garments are highly non-rigid, and capturing such deformations
often requires dense views as supervision. In this paper, we introduce
AniDress, a novel method for generating animatable human avatars in loose
clothes using very sparse multi-view videos (4-8 in our setting). To allow the
capturing and appearance learning of loose garments in such a situation, we
employ a virtual bone-based garment rigging model obtained from physics-based
simulation data. Such a model allows us to capture and render complex garment
dynamics through a set of low-dimensional bone transformations. Technically, we
develop a novel method for estimating temporal coherent garment dynamics from a
sparse multi-view video. To build a realistic rendering for unseen garment
status using coarse estimations, a pose-driven deformable neural radiance field
conditioned on both body and garment motions is introduced, providing explicit
control of both parts. At test time, the new garment poses can be captured from
unseen situations, derived from a physics-based or neural network-based
simulator to drive unseen garment dynamics. To evaluate our approach, we create
a multi-view dataset that captures loose-dressed performers with diverse
motions. Experiments show that our method is able to render natural garment
dynamics that deviate highly from the body and generalize well to both unseen
views and poses, surpassing the performance of existing methods. The code and
data will be publicly available.
