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. ![[Quick Ref]](../icons/quick_ref.gif)
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Any number of atmospheric effects may be associated with the default
medium (``air'').

- fog ^color ^thinness
Add exponential fog with the specified thinness and color.
Fog is simulated by blending the color of the fog with the color of
each ray. The amount of fog color blended into a ray color is an exponential
function of the distance from the ray origin to the point of intersection
divided by the specified thinness for each color channel.
If the distance is equal to thinness,
a ray's new color will be half of the fog color plus half its
original color.

- mist ^color ^thinness zero scale
Add global low-altitude mist of the specified color. The color of
a ray is modulated by a fog with density that varies linearly with
the difference in z coordinate
between the ray origin and
the point of intersection. The thinness values specify the transmissivity
of the fog for each color channel.
The base altitude of the
mist is given by zero, and the apparent height of the mist can
be modulated using scale, which scales the difference in
altitude used to compute the fog.

- fogdeck altitude offset ^scale chaosscale
octaves ^color ^thinness
Add low-altitude fog, with transmissivity modulated by
a chaotic function.
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. ![[Quick Ref]](../icons/quick_ref.gif)
Next: The Default Medium
Up: Surfaces and Atmospheric
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Jelle van Zeijl (jvzeijl@iso.estec.esa.nl)
Wed Jun 15 16:19:08 MET DST 1994