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1210 Chapter 15: Lights and Cameras
This value does not change during an animation.
You must choose the value, based on the size of
the scene extents.
Whenoff,thebiasiscomputedrelativetotherest
of the scene, and then normalized to 1.0. This
provides a common star t ing bias value in scenes of
any size. If the scene extents change, this interna l
normalization c an vary from fr ame to f rame.
Default=off.
Tip: Leaving Absolute Map Bias off gives good
results in most situations, because the bias is
internally balanced to match the scene size. In
animations,however,ifmovingobjectscausea
large change in the scene extents (or if objects are
unhidden, and so on), the normalized bias value
might become inappropriate, causing shadows
toflickerordisappear. Ifthishappens,turnon
AbsoluteMapBias.YouwillhavetosettheBias
control to a value appropriate for the scene. As a
rule of thumb, try a Bias value that is the distance
between the light and the target object, divided
by 100.
2-Sided Sha dows—When on, backfaces are not
ignored when calculating shadows. Objects seen
fromtheinsidearenotlitbylightsfromthe
outside. When off, backfaces a re ignored, which
can cause outside lights to illuminate object
interiors. Default=on.
Thefacesinsidetheslicedspheredonotcastshadowsif
2-Sided Shadows is not s elected.
Cam eras
Create panel > Cameras
Create menu > Cameras
Cameras present a scene from a particular point of
view. Camer a objects simulate still-im age, motion
picture, or video cameras in the real world.
With a
Camera viewport (page 3–788) you can
adjust the camera as if you were looking through
its lens. Camera viewp orts can be usef ul for
editing geometry as well as setting up a scene for
rendering. Multiple cameras can give different
views of the same scene.
The
Camera Correction modifier (page 2–1237)
letsyoucorrectacameraviewto2-point
perspective, in which vertical lines remain vertical.
If you want to animate the point of view , you can
createacameraandanimateitsposition. For
example, you might want to fly over a landscape or
walk through a building. You can animate other
camera parameters as well. For example, you can
animate the c amera’s field of view to give the effect
of zooming in on a scene.
The Display panel’s
Hide By Categor y (page 1–52)
rollout has a toggle that lets you turn the display of
camera objects on and off.
A convenient way to control the display of camera
objectsistocreatethemonaseparate
layer (page
3–704)
.Youcanhidethemquicklybyturningoff
the layer.
Tip: The Camera Match utility (page 2–1232)
allows you to start with a background photograph
and create a camera object that has the same point
of view. This is useful for site-specific scenes.
There are two kinds of camera objects: