Display location calculation means and methods for calculating a display location are disclosed. It has become common for users to indicate a point on a display in order to communicate with a machine. It is therefore necessary to be able to calculate the location on the display that is being indicated by the user. A display generator (123) is arranged in operation to generate a display in response to display data generated by a machine (111). A camera operable to generate image data representing at least part of the scene within the field of view of the camera (which part, includes at least a portion of the display) is carried in a pointer device (103). Computation means (111, 113, 115) are arranged in operation to receive the image data and the display data and to calculate from these data sets the position and/or orientation of the pointer device (103) relative to the display. A display location can then be calculated from the calculated position and/or orientation.