Rendering an image using lookup tables giving illumination values for each light source by direction and distance

摘要

A 3-D image synthesis apparatus maintains an "object database" (OBJ) defining a 3-D world to be represented on a 2-D display screen (DIS) . The object database includes light sources (LS) which have non- uniform distributions of illumination. To simplify calculations of the illumination of an object surface (P.sub.O), the apparatus pre-stores (606) one or more look-up tables. The look-up table (606) is then addressed by polar coordinates (,) calculated per pixel of the output image, to incorporate the dependency of illumination on direction. Several tables may be stored for each light source, each representing the illumination pattern at a different distance (D) from the light source. Smooth variations can be achieved by interpolation between integer values of , and D.