Graphics Programs Reference
In-Depth Information
googling), but the differences are really pretty
straightforward.
Classical
These buffers are the simplest
and can suffer from biasing artifacts (see
Figure 13-2).
Classical-Halfway
These buffers improve
on Classical and suffer less from biasing
artifacts.
Irregular
These shadow buffers always pro-
duce crisp, clean shadows with no aliasing,
but they can't be used to produce soft shad-
ows, and the shadows they create don't show
up in ray-traced reflections.
Deep
These shadow buffers are the most
advanced and can store transparency infor-
mation, allowing for partial shadowing from
transparent objects. They are ideal for ren-
dering shadows from materials like hair and
fur, as well as volumetric materials.
F i filter Ty pe
The filter type used to blend shadow
borders.
Gauss
gives the smoothest results.
Soft
This sets the softness of your shadows in
terms of the size of the lamp used to cast shad-
ows. Larger values give softer shadows but
require more samples.
Figure 13-2: Shadow-buffer biasing artifacts are shown
here with a low shadow-buffer size to exaggerate the effect.
Increasing the Bias value avoids these artifacts, but high set-
tings can cause you to lose shadows that
should
be there.
Bias
This adjusts how the shadow buffer is cal-
culated. It's used to prevent artifacts that are
caused by faces at a low angle to the lamp cast-
ing shadows on themselves (see Figure 13-2).
Higher values reduce bias artifacts but can
cause some parts of a mesh not to cast shadows
where they should, so set this as low as you can
without introducing artifacts.
will still be lit by the spot lamp but will not cast
shadows. The extent of this range is displayed in
the 3D Viewport as a solid line extending out-
ward from the lamp's center between the clip-
start and clip-end distances (see Figure 13-4).
Sample Buffers
This determines the number of
shadow buffers that are rendered. Higher values
give better anti-aliasing of hard-edged shadows,
but more buffers use more memory, so tread
carefully.
Autoclip Start/End
Turning on these options
leaves it to Blender to set the clip-start and clip-
end distances automatically based on the verti-
ces visible from the point of view of the lamp.
Size
This sets the resolution of the shadow-buffer
map (see Figure 13-3). The higher the value,
the greater the detail that can be captured
in the map and the more memory required for
rendering. If you want soft shadows, you won't
be able to see that much detail in them anyway,
so use high resolutions only for harder shadows.
Lighting in Cycles
In Cycles, lighting is broadly similar to that of
Blender Internal but with fewer options. Setting up
lighting in Cycles is easier because you get instant
feedback from the render preview. Lights in Cycles
are node based and consist of shaders, just as with
materials. In fact, Cycles allows you to incorpo-
rate the emission of light into materials
and
lamp
objects. We'll discuss both here.
Clip Start/End
These settings define the range of
distances over which objects will cast shadows
in the shadow buffer. Objects outside this range
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