8

Volume Light Environment Effect 287
Filter Shadows—
Allows you to get better quality
volume-light rendering by increasing the sampling
rate (at the cost of some 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 3–658) files, and so on.
Medium—Adjacent pixels are sampled and
averaged. This produces a very sig nificant
improvement in cases where you’re getting
banding types 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 Smp R a nge—Blurs the shadows cast in
thevolumebasedontheSampleRangevaluein
the light’s shadow parameters. Because increasing
theSmpRangevalueblurstheshadowcastbythe
light, this makes shadows in the fog better match
cast shadows, and helps prevent aliasing in the fog
shadows.
Tip: WiththeUseLightSmpRangeoption,the
higher the light’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 3–1006) parameters for the
individual light.
Note: Rendering Volume Light 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 start 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 starts
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 (p age
3–1048)
, you can keep this value at 0, and no
matter what the light’s actual Start Range, you’ll
always get a smooth glow without
hotspots (page
3–1048)
.
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