7. A system for animating a digital character according to facial expressions of a user, comprising: memory containing a program code; a display coupled to the memory; and one or more processors coupled to the memory and the display, the one or more processors configured to execute the program code, the program code configured to cause the one or more processors to: obtain a first series of two-dimensional (2D) images of a face of a user; obtain a first series of three-dimensional (3D) depth maps of the face of the user; determine 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; identify 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; track 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; determine 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 animate, based on the animation parameters, the digital character to mimic the face of the user on the display.
7. A system for animating a digital character according to facial expressions of a user, comprising: memory containing a program code; a display coupled to the memory; and one or more processors coupled to the memory and the display, the one or more processors configured to execute the program code, the program code configured to cause the one or more processors to: obtain a first series of two-dimensional (2D) images of a face of a user; obtain a first series of three-dimensional (3D) depth maps of the face of the user; determine 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; identify 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; track 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; determine 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 animate, based on the animation parameters, the digital character to mimic the face of the user on the display. 12. The system of claim 7 , wherein the program code further comprises program code to convert the expression parameters into a form readable by an animation tool to enable the animation tool to animate the digital character according to the expression parameters.