8

94 Chapter 17: Rendering
Same model rendered in mist
Mist applied as a camera volume shader; rea listic falloff
chosen.
Therearetwowaystoassignavolumeshader:
•Toacamera
This effectively makes the entire scene a single
volume.
•Toamaterial
This makes a volume out of objects to which
the material is applied.
Usually when you assign a volume shader
to a material, you want to make its surface
transparent so the shading within the volume is
visible. You can do this with the mental images
T
ransmat shader.
To assign a volume shader to a camera, use the
Render Scene dialog. To assig n a volume shader
to a material, use the material’s Volume shader
component. This component is found on the
mental ray Connect ion rollout (page 2–1305) ,and
in the
mental ray material (page 2–1385) itself. See
the “Procedures” that follow.
Pr ocedur es
To apply volume shading to a camera:
1.
Choose Customize > Preferences. Go to the
mental ray panel, and turn on Enable Mental
Ray E xtensions.
2. On the Render toolbar, click Re nder
Scene.
If the active renderer is not already the mental
ray renderer, go to the Common panel, and
on the Assign Renderer rollout, click the “...”
button for the Production renderer. A Choose
Renderer dialog is displayed. High light “mental
ray Renderer” in the list, and then click OK.
3. ClicktheRenderertabtogototheRenderer
panel. On the Camera Effects rollout, find the
Camera Shaders group, and click Volume.
The
Material/Map Browser (page 2–1256) is
displayed.
4. Cho o se a volume shader from the list in the
Browser , and then click OK.
To a pply v olume shading to an object:
1.
Choose Customize > Preferences. Go to the
mental ray panel, and turn on Enable Mental
Ray Ex tensions.
2. On the Render toolbar, click Re nder
Scene.
If the active renderer is not already the mental
ray renderer, go to the Common panel, and
on the Assign Renderer rollout, click the “...”
button for the Production renderer. A Choose
Renderer dialog is displayed. High light “mental
ray Renderer” in the list, and then click OK.
Leave the Render Scene dialog open, or
minimize it.
3. Open the Material Editor. Use the mental
ray Connection rollout (page 2–1305)
to assign
a volume shader to the Volume component.
Another technique would be to use the
mental
ray material (page 2–1385)
,andassignashader
totheVolumecomponent.