8

Using Dummy Objects 411
Usi ng D ummy Obj ects
The primar y use of dummy helper objects (page
2–15)
is to assist in creating complex motions and
building complex hierarchies. Because dummies
are invisible when rendered, they are an excellent
choice for offset joints, connectors between
objects, and handles for complex hierarchies.
Dummies and
Points (page 2–22) can act as null
objectsthatfunctionascontrolsfortransforming
parts of an IK chain.
Using a D ummy to Cont rol Mot ion
Breaking complex motions into simple
components often makes it easier to go back and
edit your animations.
Consider a bouncing ball that moves along a path.
You could animate the ball by positioning it on
many frames, but it would be very difficult for you
to go back and adjust the height of the b ounce or
the path of the ball. You have to edit the m otion
of the ball on many frames to make even a simple
change.
Usingadummyobjectsolvesthisproblemby
breaking the motion into simple components. One
component is the up and down bounce of the ball.
Theotherismovementonthepath.
Combining the bouncing motion of a ball with the for ward
motion of a dummy results in a moving bouncing ball.
Using a Dummy as a Handl e
You might want to move and animate a selection
of objects individually but als o have the ability to
transformthemasasingleobject.
A good example of this is a camera on a tripod.
Youwanttoadjustboththecameraanditstarget
individually but also want to move them together
as a single unit.
Procedures
To create a complex bounce moti on using a d ummy
obj ect:
1.
Start with a sphere, then create a dummy object
below the sphere, and link the sphere as a child
of the dummy.
2. Animate the sphere bouncing up and down
above the dummy.
3. Animate the dummy moving.
Thespherebouncesontopofthedummy
object as the dummy moves around the scene.
You can easily change the height and speed of
thebouncebychangingthesphereanimation.
You can change the path through the scene by
changing the dummy animation.
To create a camera tr i pod:
• Createadummyobjectbelowatargetcamera
and link the camera and target as children of
the dummy object.
Thecameraandthetargetfollowthedummy
object. You can quickly position the camera by
placing the dummy object and compose your
view by adjusting the camera and its target.
Animating Links
Yo u a s s i g n a Link constraint (page 2–386) to
an object to animate links from one parent to
another. You use a link const r a int instead of
using the regular Select and Link and Unlink