9

908 Glossary
is 32-bit, with the extra 8 bits of alpha providing
256 levels of transparenc y.
3dsMaxcreatesthealphachannelautomatically
when you render. Any background pixels in the
rendered image are fully transparent, and the alpha
channel also accounts for any other transparency
thatyoucreateviamaterials,etc. Youcansee
this in the rendered frame window (page 3–5) by
clicking the Display Alpha Channel button on
the toolbar: In the resulting display, black pixels
are fully transparent, white pixels are opaque,
and gray pixels show degrees of transparency. To
return to the regular display, click Display Alpha
Channel again.
To output a rendered image w ith alpha, save in an
alpha-compatible format such as TIFF or Targa.
With Targa, the default settings include saving
alpha; with TIFF, be sure to turn on the Store
Alpha Channel check box.
Ambi ent Color
Ambient color is the color of an object where it is
in shadow. This color is what the object reflects
when illuminated by ambient light rather than
direct light.
Ambient color areas in the scene will not appear
any darker than t he ambient light setting (page
3–908).
You can lock a material’s ambient color to its
diffuse color so that changing one automatically
changes the other.
Ambient Light
Left: No ambient light
Middle: Low ambient light
Right: User-adjusted ambient light
Ambient light is the general light that illuminates
the entire scene. It has a uniform intensity and is
uniformly diffuse. It has no discernible source and
no discernible direction.
By default, there’s no ambient light in a scene. If
you examine the darkest shadows on your model
w ith the default ambient lig ht setting, you cannot
makeoutthesurfacebecauseit’sunlitbyanylight.
Shadows in yo ur scene will not appear any darker
than the ambient light color, w hich is why you
usually keep ambient light set to black (or a very
dark color).
If you use photometric lights and a radiosity
solution (page 3–51),ambientlightisaccurately
calculated. The other advanced lighting option,
light tracing (page 3–44), also generates ambient
lighting.
If you use standard lig hts, a good lig hting test is to
set your ambient lighting to black (the default), set
up all your lights, and then decide at the end if you
need to increase the ambient light.
Animated Tex ture
An animated texture is a material whose properties
change over time. One example of this is assigning
a multi-frame bitmap (for example, an AV I file or
an IFL image-file sequence) as a map.