1. A method for representing a three dimensional object in a computer system capable of displaying the object in three dimensions wherein, in use: a surface of the object is approximated by a set of planar facets; a grid defining a set of nodes is imposed upon each of the facets; an object point is associated with each node of the grid; each object point is moved away from its associated node on the plane of the facet; the distance and direction of the movement is decided in a random or pseudo random manner; such that the totality of object points is used as the representation of the object.