Final Sets and Backgrounds - Animating with Blender: How to Create Short Animations from Start to Finish - page 233

Likewise, the Energy control functions exactly like it does for
raycast AO, increasing and decreasing the overall brightness of
the result.
Finally, try enabling the Pixel Cache option, which can dra-
matically speed up AAO rendering. Be aware that it is an even
further shortcut in the rendering process and may produce
undesired results. The best advice, though, is to get your AAO
settings as you like them, do a test render (possibly even a test
animation), then enable Pixel Cache and rerender for com-
parison. If everything still looks good, then go with it!

Figure 13.15 Falloff set to its highest and tightest
value

NOTE
You can choose to use the Sky option with AAO to let the sky's color affect the solution. Unlike
raycast AO, AAO does not take the Real sky option into account, so any colors you specify in the
Horizon and Zenith color blocks of the World buttons will be used as a simple up/down blend,
not as a true color horizon.

Most outdoor scenes will include direct lighting from the
sun as well. The simplest way to accomplish this sort of uni-
directional light is to use a Sun Lamp (remember—no ray
shadows!). Figure 13.16 shows the outdoor test scene that was
previously described rendered with a single Sun Lamp added.
Of course, you will need to include shadows. The best way
to do this in a controllable fashion is to duplicate the Sun
Lamp and change the new lamp to a Spot Lamp, set to Only
Shadow . Settings for the Spot Lamp used to produce Figure
13.17 are in Figure 13.18. If you set the lamp's SpotBl (Spot
Blur) to 1.0, the shadows will fade out nicely around the
edges of the lamp, allowing you to use several lamps beside
each other to shadow large areas if the need arises. Be care-
ful when using multiple shadow-casting spot lamps, though,
that the same object is not overlapped by the coverage areas of
multiple spots. This would produce multiple cast shadows and
look bad. For some shots, you may need to carefully manage
the layering of spot lamps and objects to avoid these sorts of
problems.

Figure 13.16 A Sun Lamp added

When setting up lighting for an outdoor scene, Approximate
Ambient Occlusion creates your base. Direct illumination is Figure 13.17 A Shadow Only spot lamp is added