Title: Hierarchical Radiosity with Multiresolution Meshes
Author: Andrew J. Willmott
The hierarchical radiosity algorithm solves for the global transfer of
diffuse illumination in a scene. While its potential algorithmic
complexity is superior to both previous radiosity methods and
distributed ray tracing, for scenes containing detailed polygonal
models, or highly tessellated curved surfaces, its time performance and
memory consumption are less than ideal.
My thesis is that by using hierarchies similar to those of
multiresolution models, the performance of the hierarchical radiosity
algorithm can be made sub-linear in the number of input polygons, and
thus make radiosity on scenes containing detailed models tractable. The
underlying goal of my thesis work has been to make high-speed radiosity
solutions possible with such scenes.
To achieve this goal, a new face clustering technique for automatically
partitioning polygonal models has been developed. The face clusters
produced group adjacent triangles with similar normal vectors. They are
used during radiosity solution to represent the light reflected by a
complex object at multiple levels of detail. Also, the radiosity method
is reformulated in terms of vector irradiance. Together, face clustering
and the vector formulation of radiosity permit large savings.
Excessively fine levels of detail are not accessed by the algorithm
during the bulk of the solution phase, greatly reducing its memory
requirements relative to previous methods. Consequently, the costliest
steps in the simulation can be made sub-linear in scene complexity.
I have developed a radiosity system incorporating these ideas, and shown
that its performance is far superior to existing hierarchical radiosity
algorithms, in the domain of scenes containing complex models.