Game Development Reference
In-Depth Information
Quality.
The default Quality is
High
—though this setting can be toggled between
High (for production use) and Low (for testing). The value to use here depends
on how you like to work and how long it takes to produce lightmaps and to
make adjustments. But, when building the final lightmaps for your game, be sure
to use the High quality setting.
Bounce Boost and Bounce Intensity (Pro Only feature).
Together these
values control the influence and power of indirect illumination in the lightmaps.
During the lightmap generation process, the lightmapper emits rays from all
light sources in the scene, and these travel in a straight line until they strike and
bounce away from any surfaces they contact. The bounced light loses some of
its intensity and inherits some of the color from the surface it previously hit. This
is why (for example) a white floor near a red wall will be “splashed” with a tint of
red, as light from the wall bounces and strikes the floor. In the “real world” there
is no known limit to the number of light bounces allowed. But for computers,
this kind of potentially infinite regression is not permitted, and so a concrete
limit must be set on the number of bounces. This limit is controlled by
Bounce
Boost
. Higher values theoretically produce more accurate and believable results
at the cost of calculation time. In practice, however, you don't usually need to
go very high for results that are “believable enough.” The
Bounce Intensity
value
is a multiplier (brightness increase) for each bounced ray. For the CMOD level
in Figure
2-29
, I think the values of 1.38 and 1.42 work for Bounce Boost and
Intensity, respectively. I did not calculate these numbers in anyway. I simply
played around and made multiple lightmap bakes, tweaking the settings and
trying again several times, before finally settling on these values. Through
successive builds and refinement you can arrive at values that work best for you.
Ambient Occlusion (Pro Only feature).
Ambient Occlusion (AO) simulates
one symptom of indirect illumination known as
Contact Shadows
. This refers
to the darkening that occurs inside and near the crevices that form when two
solid surfaces meet, such as where the floor meets a wall, or a coffee mug
base meets the table. In and around those regions there's a thin border of
shadow or darkening that results because light rays are more occluded or
blocked from those regions. By using Ambient Occlusion, you can enhance
the general volume of your environments and the embeddedness of your
objects—making them feel much more of an integrated part of the world. By
default, Ambient Occlusion is disabled. You can enable it (on the Pro version
of Unity) by switching the Ambient Occlusion slider to a value above 0. A value
of 1 means AO will take full effect, and lower values between 0 and 1 act as an
opacity control. The Ambient Occlusion slider works in combination with the
Max Distance
and
Contrast
sliders to control the size and darkness of the AO
shadows generated in crevices. For CMOD, the values of 0.1 and 1 work well for
Max Distance and Contrast, respectively.
