EP1235186A2 — Virtual lighting

USPTO Abstract

An image expression method for expressing illumination light from a light source placed in a virtual three-dimensional space by image processing employing a computer. The method comprises the step of disposing a plurality of polygons, each of which corresponds to a shape of a transverse cross section at each position of a virtual region that gradually expands with advancement from the light source in an optic axis direction, at respective positions spaced from each other on the optic axis of the illumination light so that a normal of each polygon is oriented toward a view point set in the virtual three-dimensional space, the respective positions being set in such a manner that at least adjacent polygons are partially superimposed on each other. A texture is mapped that expresses divergence of the illumination light to each polygon, and a size of the virtual region in a direction orthogonal to the optic axis based on a distance from a view point to the light source is changed. A magnification of the virtual region to the distance from the light source based on a relationship between the optic axis and a direction in which the light source is viewed from the view point is then differentiated.