  Despite the frequent appearance in the radiation heat transfer literature of
articles describing Monte Carlo ray-trace (MCRT) applications to
two-dimensional enclosures, no formal verification may be found of the method
commonly used to determine the directional distribution of diffuse emission and
reflection when estimating two-dimensional radiation distribution factors.
Considered are two methods for determining the direction cosines in this
situation. The results are shown to be in agreement with those obtained in the
limiting case of a three-dimensional enclosure as one of its dimensions is
increased.
