A method of assembling an apparatus for use in performing pattern recognition, the method involves placing a module and a housing relative to one another, the housing being supported relative to an object having an optical marker, and the module comprising a camera for generating a camera output indicative of a scene in the field-of-view of the camera, using the camera output to determine the position of the marker in the field-of-view of the camera, moving the module and the housing relative to one another until the marker is at a predetermined location in the field-of-view of the camera and then fixing the position of the module relative to the housing.
