Perceptually-Driven Radiosity
S. Gibson, Roger Hubbold.
Computer Graphics Forum, 16(2), June 1997, pp 129-140.
Abstract
We present a new approach to radiosity simulation that uses
perceptually-based measures to control the generation of view-independent
radiosity solutions. This enables computational effort to be moved away
from areas that are deemed to have a visually insignificant effect on the
solution's appearance, into those that are more noticeable. We achieve this
with an a-priori estimate of the real-world adaptation luminance, and use a
tone-reproduction operator to transform luminance values to display colours
during the solution process. The distance between two colours in a
perceptually-uniform colour space is then used as a numerical measure of
their perceived difference. We describe an oracle that stops patch
refinement once the difference between successive levels of elements
becomes perceptually unnoticeable. We also show how the perceived
importance of any potential shadow falling across a receiving element can
be determined. This is then used to control the number of rays that are
cast during visibility computations, giving reductions of almost 93% in
the total number of rays required for a solution without any significant
loss in image quality. Finally, we discuss how perceptual knowledge can be
used to optimise the element mesh for faster interactive display and to
save memory during computation.
Copyright The Eurographics Association 1997, Published by
Blackwell Publishers, 108 Cowley Road, Oxford OX4 1JF, UK and 350 Main
Street, Cambridge, MA 02148, USA.