There are two main ways of capturing vector data for use in a GIS. One can digitise the vector features on a digitising tablet or table or one can head-up digitise features from an image. In both instances the original, on paper or as a digital image, has to be registered to a co-ordinate system. Digitising from an original on a digitising table is the most accurate way of data capture, as scanning of an image for use of head-up digitising can introduce errors caused by distortion during the scanning process.