2008

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.
Multiple apparatus objects can display the same fog effect.
You can pick multiple gizmos. Click Pick Gizmo and then press H. This opens
the Pick Object dialog, which lets you choose multiple objects from a list.
Changing the dimensions of a gizmo changes the region that fog affects, but
doesn'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.
Remove Gizmo Removes a gizmo from the volume fog effect. Select the
gizmo in the list, and then click Remove Gizmo.
Soften Gizmo Edges Feathers the edges of the volume fog effect. The higher
the value, the softer the edges. Range=0 to 1.0.
TIP Don't set this value to 0. At 0, Soften Gizmo Edges can cause aliased edges.
Volume group
Color Sets the color for the fog. Click the color swatch, and then select the
color you want in the
Color Selector on page 331 .
You can animate the color effect by changing the fog color at a nonzero frame
with Auto Key on.
Exponential Increases density exponentially with distance. When turned
off, density increases linearly with distance. Activate this check box only when
you want to render transparent objects in volume fog.
TIP If you turn on Exponential, increase the Step Size value to avoid banding.
Density Controls the fog density. Range=0 to 20 (anything over that tends
to obliterate the scene).
6516 | Chapter 19 Effects and Environments