9

Volume Light Environment Effect 291
Filter Shadows—
Allows you to get better quality
volume-light rendering by increasing t he sampling
rate (at the cost of s ome increased rendering time).
Thesearetheoptions:
Low—The image buffer is not filtered but directly
sampled instead. This option is fine for 8-bit
images, AVI (page 3–609) files, and s o on.
Medium—Adjacent pixels are sampled and
averaged. This produces a very significant
improvement in cases where you’re getting
banding t ypes of ar tifacts. It is slower than Low.
High—Adjacent pixels and the diagonal pixels are
sampled, and each are given different weights.
This is the slowest method and provides somewhat
better quality than Medium.
Use Light S mp R ange—Blurs the shadows cast in
thevolumebasedontheSampleRangevaluein
the light’s shadow parameters. Because increasing
theSmpRangevalueblurstheshadowcastbythe
light, this makes shadows in t he fog be tter match
cast shadows, and helps prevent aliasing in the fog
shadows.
Tip: WiththeUseLightSmpRangeoption,the
higher the lig ht’s Smp Range value, the slower
the rendering . However, with this option you
can usually get good results with a lower Sample
Volume % setting (such as 4 ), which reduces
rendering time.
Sample Volume % —Controlstherateatwhich
the volume is sampled. Ranges 1 through 10,000
(where 1 is the lowest quality and 10,000 is the
highest quality).
Auto—ControlstheSampleVolume%parameter
automatically and disables the spinner (this is the
default). The preset sampling rates are as follows:
low=8; medium=25; hig h =50
Because the parameter ranges up to 100 there’s
still room to set it higher. Increasing the Sample
Volume % parameter definitely slows things down,
but in some cases you may want to increase it (for
extremely high sample quality).
Left: Original scene
Right: Increasing sample volume to improve quality
Attenuation group
The controls in this section are contingent upon
the settings of the Start Range and End Range
attenuation (page 3–912) parameters for the
individual light.
Note: Rendering Volume Lig ht at some angles can
introduce aliasing problems. To eliminate aliasing
problems, activate the Near and Far Attenuation
settings in the light object that the Volume Light
applied to.
Start % —Sets the sta rt attenuation of the light
effect, relative to the actual light parameter’s
attenuation. It defaults to 100 percent, which
means that it starts attenuating at the Start Range
point. When you reduce this parameter, it star ts
attenuating the light at a reduced percentage of the
actual Start Range value that is, closer to the light
itself.
Because you usually want a smooth falloff (page
3–954), you can keep t his value at 0, and no matter
what the light’s ac tua l Start R ange, you’ll always
get a smooth glow without hotspots (page 3–954).
End % —Sets the end attenuation of the lighting
effect, relative to the actual light parameter’s
attenuation. By setting this lower than 100 percent,
you can have a glowing attenuating light that