04/11/2002
15-462 Graphics I
11
Progressive Refinement
•Shoot
light instead of gathering light
•Basic
algorithm
–Initialize
emitting element with Bi = Ei
–Initialize
others with with Bi = 0
–Pick
source i (start with brightest)
–Using
hemicube around source, calculate Fi j
–For
each j ¹ i, approximate B’j = rj Bi Fi j (Ai / Aj)
–Pick
next source i and iterate until convergence
•Each
iteration is O(n)
•May or
may not keep Fi j after
each iteration