1. A method of animating a digital character based on facial expressions of a user, comprising: obtaining a first series of two-dimensional (2D) images of a face of a user; obtaining a first series of three-dimensional (3D) depth maps of the face of the user; determining a set of blendshape weights associated with a generic expression model based on at least some of the first series of 2D images and at least some of the first series of 3D depth maps, the generic expression model representative of a generic person; identifying expression parameters for a user-specific expression model based on at least some of the set of blendshape weights, the user-specific expression model representative of the face of the user; tracking the face of the user by decoupling rigid motion of the user from non-rigid motion of the user based on at least some of the first series of 2D images and at least some of the first series of 3D depth maps, wherein the rigid motion represents a movement of the 3D depth map of the face of the user and the non-rigid motion represents a change in expression of the face of the user; determining animation parameters for a digital character based on the expression parameters, the rigid and non-rigid motions of the user, and an animation prior, the animation prior including a collection of animation parameters of the digital character, the animation prior indicative of a pre-defined animation of the generic expression model; and animating, based on the animation parameters, the digital character to mimic the face of the user.