Abstract:
The gathering radiosity is a popular method for investigating the lighting
effects in a closed environment. In lighting simulations, the locations
of
objects and light sources usually remain fixed, whereas the intensity
and color of light sources and/or reflectivity of objects vary in time.
For lighting simulations, after the form-factor values are computed and
stored, the linear system of equations are solved repeatedly to visualize
the effect of these changes. Therefore, efficient implementation of the
solution phase becomes crucial for such applications. The Scaled Conjugate-Gradient
(SCG) method is known to be a powerful technique for the solution of large
sparse linear system of equations with symmetric positive definite matrices.
In this paper, the utilization and parallelization of SCGmethod is investigated
for the solution phase. The non-symmetric form-factor matrix is efficiently
transformed into a symmetric matrix. An efficient data redistribution scheme
is proposed to achieve almost perfect load balance in the solution phase.
Several parallel algorithms for the form-factor computation phase are also
presented. The relative performance of the proposed algorithms are experimented
on a 16-processor Intel's iPSC/2 hypercube multicomputer. Very high efficiency
values are obtained for sufficiently large granularity.