Building animatable 3D models is challenging due to the need for 3D scans,
laborious registration, and manual rigging, which are difficult to scale to
arbitrary categories. Recently, differentiable rendering provides a pathway to
obtain high-quality 3D models from monocular videos, but these are limited to
rigid categories or single instances. We present RAC that builds category 3D
models from monocular videos while disentangling variations over instances and
motion over time. Three key ideas are introduced to solve this problem: (1)
specializing a skeleton to instances via optimization, (2) a method for latent
space regularization that encourages shared structure across a category while
maintaining instance details, and (3) using 3D background models to disentangle
objects from the background. We show that 3D models of humans, cats, and dogs
can be learned from 50-100 internet videos.

利用可微分渲染实现从单个视频中生成人，猫和狗等动物的可动态三维模型，并通过优化特定的骨架实现实例化，使用潜在空间正则化鼓励类别间的共享结构并同时维护实例的细节和使用三维背景模型将对象与背景分离。