1. A computer-implemented method comprising: obtaining a three-dimensional scan of a subject; generating a customized digital model including a set of blendshapes using the three-dimensional scan, each of one or more blendshapes of the set of blendshapes representing at least a portion of a characteristic of the subject; receiving input data of the subject, the input data including video data and depth data; tracking body deformations of the subject by fitting the input data using one or more of the blendshapes of the set; and fitting a refined linear model onto the input data using one or more adaptive principal component analysis shapes.