Abstract: In order to generate a two-dimensional image of an object, three-dimensional model data is used. Drawing rules are stored which correspond to features of the object. Each drawing rule corresponds to a two-dimensional representation of the corresponding feature when that feature is viewed from a particular viewing direction. The drawing rule corresponds, in each case, to a predetermined visual presentation or appearance of the feature from the corresponding viewing direction. The user then selects the viewing direction and the two-dimensional image is generated using the model data and the appropriate drawing rule or rules. In this way, a feature of the object may be shown in the two-dimensional image with a visual presentation or appearance which is appropriate even if the visual presentation or appearance does not result from the model data. The feature may then be shown in a way which corresponds to the purpose to which the two-dimensional image is to be put.

Abstract: An area set operation apparatus effecting a set operation of a plurality of n-dimensional areas positioned in a n-dimensional finite space, wherein n (n.gtoreq.