Final Sets and Backgrounds - Animating with Blender: How to Create Short Animations from Start to Finish - page 231

Lighting Exterior Shots

The easiest way to light an outdoor scene is to enable Ambient Occlusion with the Sky Texture option, throw
in a sun lamp, and turn on ray shadows.

Are red lights fl ashing and sirens going off in your head? They should be. The AO sun lamp method is not

going to work for animation.

Fortunately, there is a new nonray-based ambient occlusion method available. One of the downsides of the
original ray-based AO, besides its lack of speed, is that even at maximum quality, it is not completely smooth,
giving a slight grain to every surface it touches. This grain is different on every frame and could produce a
noisy effect when animated. That made it unusable on everything but the highest (slowest) quality settings.
Although the new Approximate method of Ambient Occlusion takes more tweaking to get right than the ray
based variety, which is pretty much “fi re and forget,” the results are relatively quick, smooth, and produce con-
sistent renders across frames. Figure 13.9 shows both AO methods used on the Beast with no other lighting.

Figure 13.9 The Beast in the fi eld with both raycast AO (24:70) on the highest quality level and approximate AO (0:42)

The options for Approximate Ambient Occlusion (AAO) are
a bit obscure, so let's examine how to use them to fi x prob-
lems you may encounter with the default values. Figure
13.10 shows the default values on the Amb Occ panel of
the World buttons .

In Figure 13.11, notice how the areas that have been darkened
by AAO seem unusually dark. This is one of the downsides
of AAO—areas that have faces pointing in the same direction
will tend to reinforce the occlusion effect. To fi x this, there
are two methods: raising the Passes value, which attempts to
cull duplicate faces from the solution before rendering, and
raising the Correction value, which simply tries to reduce

Figure 13.10 Approximate Ambient Occlusion

defaults