9

Radiosity Processing Parameters Rollout 65
Once the f ul l Initial Quality p ercent age has been
reached, clicking Continue has no effect.
Stop—Stops the radiosity processing. The Start
menu changes to Continue. You can later click
Continue to resume radiosity processing, as
described for the Start menu.
Keyboard shortcut:
Esc
Process group
The options in this group set the b ehavior of the
first two stages of the radiosity solution, Initial
Quality and Refine.
Initial Quality —Sets the quality percentage at
which to stop the Initial Quality stage, up to
100%. For example, if you specify 80%, you will
get a radiosity solution that is 80% accurate in
energy distribution. A goal of 80 to 85% is usually
sufficient for good results.
During the Initial Quality stage, the radiosity
enginebouncesraysaroundthesceneand
distributes energy on surfaces. Between each
iteration,theenginemeasurestheamountof
variance (noise b etween surfaces) that was
computed.
Most of the brightness of the scene is dist ributed in
the early iterations. The contribution to the scene’s
average brightness decreases logarithmically
between iterations. Af ter the first few iterations,
the brightness of the scene does not increase much,
but subsequent iterations reduce the variance in
the scene.
Note: The “quality” refers to the accuracy of
energy distribution, not to the visual quality of the
solution. Even at a high Initial Quality percentage,
the scene can still show considerable variance.
This variance is resolved by the subsequent stages
of the solution.
Increasing the percentage value of Initial Quality.
Increasing quality does not greatly increase the average
brightness of the scene, but it decreases the variance between
different surfaces in the scene, such as the faces of the sphere.
Ref ine I tera tions (All Objects)—Sets the number
of Refine iterations to perform for the scene as a
whole. The Refine Iterations stage increases the
quality of the radiosity processing on all objects
in the scene. Ga thers energy from each face in
order to reduce the var iance between faces using
a different process from the Initial Quality stage.
This stage do es not increase the brightness of
the s cene, but it improves the visual quality of
the solution and significan tly reduces variance
between surfaces. If you don’t reach an acceptable
result after processing a certain number of Refine
iterations, you can increase the number and
continue processing.
Tip: If you plan to use Regathering at render time,
you generally don’t need to perform the Refine
stage to get good-qualit y final renderings.
Note: After 3ds Max processes Refine Iterations,
Initial Quality is dis abled and you can’t change it
until you click Reset or Reset All.