
354 Virtual Reality: Concepts and Technologies
with the simple shape factor:
F
i
j
=
1
A
x
x
K (x, x
)dAdA
=
1
A
i
A
i
A
j
K (x, x
)dA
i
dA
j
(15.18)
The method of radiosity has been improved several times after its introduction in image
synthesis. The hierarchical resolution (Hanrahan et al., 1991) decreases the complex-
ity by solving it at different levels, which gives a multiresolution approach using the
wavelets functions for the projection of radiosity (Gortler et al., 1993b). In fact, when
the surfaces are distant, a rough subdivision is sufficient to obtain good results, whereas
when the surfaces are closer, a finer subdivision becomes necessary. Smits et ...