1. An apparatus comprising: a target device; an imaging device that generates a plurality of images of a target formed by the target device as the target device is rotated relative to the imaging device about a pivot axis formed at an interface between a first structure and a second structure in response to the first structure being rotated about the pivot axis relative to the second structure; and a calibrator that identifies a plurality of angles of the target about the pivot axis using the plurality of images and identifies calibration information using the plurality of angles.