In CG, you must fake certain traits of light in the real world. Using certain methods, you
can create smoky light beams, glowing lights, and lens flares. Although some of these
effects fall under the domain of rendering and shader tricks, they are best explored in the
context of lighting, as they are indeed created by light in the real world.
How do you create an effect such as a flashlight beam shining through fog? This lighting
effect is called volumetric lighting, and you can use it to create some stunning results,
which can sometimes be time consuming to render.
You cannot apply volumetric effects to Ambient and Directional light types. To add a
volumetric effect to any of the other types of lights, select the light, and in the Attribute
Editor under the Light Effects section, click the checkered Map button to the right of the
Light Fog attribute. This will create a new render node that will appear in the Hypershade
and Multilister windows. Once you click the Map button, the Attribute Editor will take
you to the lightFog node.
The way Maya handles volumetric lights is to attach a lightFog node to the light. The
Color and Density attributes under this node control the brightness, thickness, and color
of the fog attached to that light. Furthermore, in the light’s Attribute Editor, you can con-
trol the fog with the Fog Spread and Fog Intensity settings. Fog Intensity increases the
brightness of the fog, and Fog Spread controls how well the fog is defined within its con-
fines. For example, a Spot light with a fog will show the fog in its cone. Figure 10.39 shows
how spread affects the conical fog shape.
Smoother GI solu-
tion offers a nicer
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