1. A method comprising: by one or more computing devices, receiving an identifying feature of a target entity, the identifying feature requiring that the target entity to be in a line of sight of a camera for the camera to recognize the identifying feature, the identifying feature selected from the group consisting of a barcode associated with the target entity, a Quick Response code associated with the target entity, a color of the target entity, and a pattern of the target entity; locating the target entity using the camera based on the identifying feature and without using any radio frequency identifiers; and tracking the target entity using the camera based on the identifying feature, including: periodically capturing digital images with the camera; identifying the target entity in the captured digital images based on recognition of the identifying feature in the captured digital images; and following the target entity with the camera optics by moving the camera optics as the target moves.