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286 Chapter 18: Effects and Environments
Inter face
TheVolumeFogParametersrolloutappears
when you select Volume Fog under Effects in the
Environmentdialog.TheVolumeFogParameters
rollout has the following controls.
Gizmos group
By default, volume fog fills the entire scene.
However, you can choose a gizmo (an atmospheric
apparatus) to contain the fog. The gizmo can be
a sphere, a box, a cylinder , or some combination
of these.
Pick Gizmo—Click to enter Pick mode and click an
atmospheric apparatus in the scene. The apparatus
contains the volume fog when you render. The
name of the apparatus is added to the apparatus
list.
Mult iple apparatus objects can display the same
fog effect.
You can pick multiple gizmos. Click Pick Gizmo
and then press
H . ThisdisplaysaPickObject
dialog on which you choose multiple objects from
the list.
Changing the dimensions of a gizmo changes the
region that fog affects, but do esn’t change the scale
of the fog and its noise. For example, reducing
the radius of a spherical gizmo crops the fog, and
moving the gizmo changes the fog’s appearance.
Wa rn in g : When you press Shift while copying a
gizmo, the new gizmo isn’t bound to the volume fog.
If you want to use the new gizmo, you must use Pick
Gizmo to add it explic itly.
Remove Gizmo—
Removes a gizmo from the
volume fog effect. Select the gizmo in the list, and
then click Remove Gizmo.
Sof ten Gi zmo Edges—Feathers the edges of the
volume fog effect. The hig her the va lue, the s ofter
the edges. R ange=0 to 1.0.
Tip: Don’tsetthisvalueto0.At0,SoftenGizmo
Edges can cause a liased edges.
Volume group
Co lor—Sets the color for the fog. Click the color
swatch, and then select the color you w ant in the
Color Selector (page 1–161).
You c an animate the color effect by changing the
fog color at a nonzero frame with the Auto K ey
button on.
Ex ponential—Increases density exponentially with
distance. When turned off, density increases
linearly with distance. Activate this check box only
when you want to render t ransparent objects in
volume fog.
Tip: IfyouturnonExponential,increasetheStep
Size value to avoid banding.
Density —Controls the fog density. Range=0 to 20
(anything over that tends to obliterate the scene).