Graphics Programs Reference
In-Depth Information
Cycles also supports ambient occlusion, which
can be used to add white ambient light to a scene,
with occlusion based on the distance between
faces. You can turn this effect on in the World
tab of the Properties editor by using the Ambient
Occlusion tab.
Also in the World tab under Settings is the
option to sample the background as a lamp. Enable
this when using a textured background, particularly
when using HDRI (high-dynamic-range image) maps
for background lighting to dramatically speed up ren-
dering (see Figure 13-10).
World Settings in Cycles
In Cycles, World settings are node based and use the
same shader system as do materials and lights. The
World settings use the Background Shader node
exclusively, which lights the scene and sets the back-
ground color or texture (depending on the inputs
you supply it with) and the strength of the lighting
that the background contributes. The standard
background node tree is shown in Figure 13-8.
You can influence the color of the background
as with other materials by using textures, images,
and colors. Particularly useful for this are the Sky
Texture and Environment Texture nodes. The
Sky Texture node creates a procedural sky, using
the direction you set by dragging the sphere input
of the node, with the level of atmospheric scatter-
ing determined by the Turbidity setting. This effect
works particularly well when combined with a sun
lamp with a yellow-orange (sunlight) color to get
some basic outdoor lighting (see Figure 13-9).
Lighting the Bat Creature
For the Bat Creature, I wanted dramatic lighting to
make the character look dangerous and forebod-
ing. I needed some dark shadows and stark lighting
that wouldn't give too much away. To create this
effect, I used a three-point lighting setup, which is
commonly used to light characters and portraits.
Additionally, I needed to set up my lights to cre-
ate good shadows with the creature's hair and to
light the creature from behind so that light would
be seen scattering through the skin of the wings
(using the subsurface scattering material we cre-
ated in Chapter 12).
Figure 13-8: The standard node tree for World settings in
Cycles
Figure 13-9: Combining the sky shader for the background with a sun lamp gives a decent approximation of outdoor lighting.
Left: The sky shader. Right: Illumination from the sky combined with a sun lamp.
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