Form factors are used in radiosity image synthesis to describe the fraction
of diffusely reflected light leaving one surface and reaching another. The
y incorporate fundamental geometric properties of interacting surfaces used
for light transfer computation. Many numerical applications such as realis
tic image synthesis require accurate and simple formula for the form factor
s from small oriented differential areas (treated as a point with a normal)
to different geometrical objects; a disk was used in this paper. The exact
analytic solution for the general point-to-disk form factor integral is us
ed to develop more accurate numerical techniques for form factor integratio
n for surfaces commonly in use. The improvements are illustrated with reali
stic image synthesis. (C) 1999 Elsevier Science Ltd. All rights reserved.