1. A method of processing data defining a plurality of images of an object recorded at different positions and orientations to generate data defining a three-dimensional computer model of the object, comprising: receiving image data defining a plurality of images of an object recorded at different positions and orientations, and data defining the positions and orientations; processing the image data to segment data relating to the object from other image data in at least some of the images; generating data for display to a user showing the results of the segmentation processing; receiving signals input by the user defining changes to the result of the segmentation processing on at least one image; amending the results of the segmentation processing in accordance with the signals received from the user; and generating data defining a three-dimensional computer model of the object using the results of the segmentation processing, including any amended results, and the data defining the positions and orientations at which the images were recorded.