A system for determining the location of a toolpiece, the system comprising: a tool carrying a toolpiece and comprising an imaging device for capturing images of the environment around the tool, the tool being actuable to manipulate the toolpiece to work on a workpiece; and an image processor remote from the tool and communicatively coupled to the imaging device for receiving images therefrom and having access to reference data representing an expected environment, the image processor being configured to compare an image captured by the imaging device with the reference data to identify a match therebetween and to determine in dependence on characteristics of that match the location of the toolpiece; wherein the system is configured to cause the tool to transmit images captured by the imaging device to the image processor in response to actuation of the tool.