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1346 Chapter 15: Lights and Cameras
Attenuation (page 3–912) is the effect of light
diminishingoverdistance.In3dsMax,youcan
set attenuation va lues explicitly. The effects can
vary from real-world lights, giving you more direct
control ove r how lights fade in or fade out.
Note: With no attenuation, an object can
paradoxicallyappeartogrowbrighterasitmoves
away from the light source. This is because the
angle of incidence m ore closely approaches 0
degrees for more of the object’s faces.
Twosetsofvaluescontrolattenuationforobjects.
The Far attenuation value sets the distance at which
the light drops off to zero. The Near attenuation
value sets the distance at which the light "fades
in." Both these controls are turned on and off by a
toggle called Use.
When Use is set for far attenuation, the light at
itssourceusesthevaluespecifiedbyitscolorand
multiplier controls. It remains at this value from
thesourcetothedistancespecifiedbyStart,then
itsvaluedropsofftozeroatthedistancespecified
by End.
Adding attenuation to a scene
When Use is set for Near attenuation, the lig ht
valueremainsatzerouptothedistancespecified
by Start. From Start to the distance specified by
End, its value increases. Beyond End, the light
remainsatthevaluespecifiedbythecolorand
multiplier controls, unless far attenuation is also
active.
You can’t set the Near and Far attenuation
distances so they overlap.
TheDecaycontrolsareanadditionalwaytomake
alightfadeout.
Tip: When lights are attenuated, the light might
betoobrightonnearsurfacesortoodimonfar
surfaces. If you see this in renderings, exposure
control can help correct the problem. It adjusts the
larger dynamic r ange of the (simulated) physical
scene, into the smaller dynamic range of the
display. See Environment Panel (page 3–272) for
additional information on exposure control.
Procedures
To choose the color of a light using the color selector:
1.
Click the color swatch next to the On check box.
AmodalColor Selector (page 1–161) is
displayed.
2. UsetheColorSelectortochooseanewcolor,
and then click OK.
Shaded viewports update to show the new light
color, which also appears in renderings.
To change a light’s intensity:
•Increasethelight’sMultipliervalue.
To use a ttenuation:
1.
SettheStartandEndvalues.
2. Tu r n on Use.
A ttenuation is now in effect for this light when
the scene is shaded or rendered.
Note: You can also change the decay type (and
values) to reduce the light’s intensity over
distance.
To see the attenuat ion ra nge in v iewpor ts:
• Set Show for far or near attenuation.
You can preview the effect of attenuation in
shaded viewpor ts only if you turn this on as an
option in viewport preferences (page 3–821).