1. A system comprising: one or more image capture devices that capture a sequence of images; one or more processors; and one or more memories storing instructions that, when executed by the one or more processors, cause the system to: compute optical flow of movement of an object within the sequence of images; extract motion features based at least in part on the optical flow of the movement of the object within the sequence of images, wherein the motion features characterize part-centric motion that is associated with typical movement of an individual part of a particular type of object and that is useful in distinguishing the particular type of object from other types of objects; and determine, based at least in part on the motion features, that the optical flow of the movement of the object characterizes the particular type of object within the sequence of images.