A system for determining the location of a toolpiece, wherein: the toolpiece is carried by a tool and the tool comprises an imaging device for capturing images of the environment around the tool; and the system comprises an image processor communicatively coupled to the imaging device for receiving images therefrom and having access to one or more reference images of an expected environment, the image processor being configured to compare an image captured by the imaging device with at least one reference image to identify a match therebetween and to determine in dependence on characteristics of that match the location of the toolpiece.