9.5.2

338 • CHAPTER 7
OBJECTS MENU • LIGHTING • 339
Inverse Volumetric
Enabling the Inverse Volumetric function has the interesting effect of inverting your volumetric
light — that is, the light is visible where the light cone would normally be in shadow. Imagine a
company logo, behind which you have placed an Inverse Volumetric light source. This inverts the light’s
volumetric effect, giving the impression that the light is radiating from the logo itself.
Types of noise
This section describes the different types of noise you can select for the Noise option on the General
page. The Noise page itself is described later in this chapter.
Illumination. Visibility. Both.
Effects such as animated fog or sun ares can be achieved using this feature without having to use
potentially time consuming volume shaders. However, keep in mind that lights with a noise effect
have a small price to pay in rendering time, as any light using the Noise feature is slower to calculate
than one without.
Illumination
You can add irregularities to your light source in order to give it a realistic appearance. A light’s
illuminated surface is very rarely evenly lit — particularly if dust or small particles are present.
Visibility
This option adds irregularities not to your lit surface, but to the visible light itself. For example, you
can simulate rolling fog that is visible in the light cone.
Both
Ensures that both the basic light and any visible light are provided with noise irregularities.