Specialized Animation Techniques
a number of objects and tools that can be used to animate a
scene, including motion paths, nonlinear deformers, skeletons, and blend shape.
We have also looked at the process of keyframing within the Timeline and within the
Blend Shape Window. We have used the Graph Editor to rene and to reuse motion.
In this chapter, we are going to look at creating an entire skeleton and using it to animate
a model. We will also look at active bodies and their collisions, natural elds, animating
the transparency of an object, and using scripts to animate a model with an expression.
SKELETONS, INVERSE KINEMATICS HANDLES, RIGGING,
AND SKINNING A SIMPLE HUMANOID
Models of humans are typically animated by using a skeleton. But because people’s
movements are so complex, and because we instantly recognize unnatural movements,
building and animating a human skeleton is a daunting task. Luckily, Maya has some-
thing powerful to help us: a skeleton generator.
HIK: The Skeleton Maker in Maya
In Chapter 7, we looked at a simple skeleton: a human leg. We noted the key dierence
between forward kinematics (FK) and inverse kinematics (IK). With FK, if a joint higher
in the hierarchy is moved, all joints below follow along, and if we move a lower joint, and
other joints need to move as well, we generally have to manually move those joints. With IK,
we can move a joint lower in the hierarchy, and the joints above it will move accordingly. If
a human wants to grab an object that is beyond his reach, the hips and the legs will move,
too. is lets us naturally model the coordinated, skeleton-wide movement that real-world
humans and creatures exhibit. Now we look at the tool within Maya that will generate IK
skeletons for us.
e skeleton generator lets us build a tailored skeleton for a biped. It creates a complete,
integrated set of IK controls. Autodesk calls this feature “HIK,” for human inverse kinematics.
In Figure11.1, we see one of the generic characters that can be purchased from the Daz
site. He is an anime guy named Hiro: we have seen him already, when we gave him a nice