| It's no secret that Maya is particularly suited to character animation. Characters such as Stuart Little and Aki from the Final Fantasy film have cemented Maya's reputation for 3D character animation. Maya offers powerful and rich tools to animate characters in virtually any way you want. With this versatility and power comes the need, as with any art, to commit the time it takes to build up your skills as a 3D artist. Early animation tools didn't offer skeletons and skeletal deformation. Animation had to use simple rotations, so characters had doll-like arms and legs with ball sockets where they connected. Naturally, it wasn't long before animators wanted to animate characters with richer surface detail than a cockroach's compartmentalized exoskeleton. The general approach is to create a continuous surface model that doesn't have visible breaks or seamed areas. Next, a set of linked joints are constructed and placed inside the character, similar to the armatures that claymation animators put in their characters. note Claymation uses a wire that's twisted into the general shape of a character, which then has clay applied over it. This inner wire skeleton is referred to as the armature.
Finally, the joints are connected to the continuous surface model through the process of skinning. By default, many joints don't bend as naturally as animators would like, so they must modify how joints bend the skin at each trouble spot. Skinning a complex character so that it has a full range of natural motion can take several days. When skinning is complete, the bones bend within the character to deform its skin and clothes in a natural way. To make character animation focused and straightforward, large firms use specialists known as technical directors to add handles, menus, dialogs, movement constraints, and other tools for a character. This process, often called rigging, makes the character- animation process more straightforward. Rigging adds specific controls and custom movement options for character animation for example, knees should bend forward and not backward. Character rigging is a complex subject that's worthy of its own book, but this chapter covers some basic approaches so that you can learn the fundamentals. In this chapter, you learn the basics of each major element of character animation. Maya offers many ways to solve each task, but the tutorials focus on the most mainstream methods to get you started. Other methods are mentioned, however, so that you know what topics to explore next. Here are some of the concepts and techniques covered in this chapter: Creating skeletons You can build, link, and edit collections of joints to make a skeleton for any type of creature. Creating Inverse Kinematics Easy animation is possible through Inverse Kinematics (IK), in which joints automatically rotate in response to moving an IK handle at the end of a joint chain. Skinning The process by which the character's skeleton is attached to the model's surface geometry. Character rigging Adding easy-to-select objects to control the character makes animation much easier. Adding flexors Rigidly bound skeletons require a special deformer called a flexor to modify the way the skin bends around joints. Auto Key This Maya feature automatically sets a new keyframe when it senses that you've changed a variable on an animated timeline. It's a handy way to create animation keys automatically. Trax A tool to work with animation as "clips" and shuffle them on a timeline. Blend Shapes A deformer for blending the shape of one surface into the shape of another surface (or surfaces).
Key Terms skeleton A combination of connected joints. Inverse Kinematics In linked hierarchies, moving the last joint (actually a "handle" at the end joint created for Inverse Kinematics) to cause all the in-between joints to automatically rotate to reach a specific pose. For example, you move a character's hand, and the forearm, bicep, and torso adjust within defined parameters to "reach" wherever the hand was placed. Often abbreviated as IK. Forward Kinematics In linked skeletal hierarchies, rotating joints starting at the root joint and ending at the last joint to reach a specific pose. For example, you might pose a character's torso, then bicep, then forearm, and then hand to have the character reach upward. Often abbreviated as FK. end effector When IK is applied in Maya, a special controller is created with handles at each end. The end that manipulates the IK chain is called the end effector. skinning The process by which a character's skeleton is attached to the model's surface. joint The pivot points of a skeleton. These deformers influence how the surface area behaves on a skinned model. root joint The base joint of a skeleton. joint chain A connected hierarchy of joints within a skeleton. bind pose The position of the skeleton and model when skinning is applied; generally a neutral pose with limbs spread to facilitate skinning. clip A defined set of animation frames for use in Trax. Blend Shape A deformer that enables you to assign other surfaces to the current surface as targets to be blended into. The Blend Shape deformer creates a special dialog box with sliders, used to control the percentage of deformation each blend shape should have on the base model. This technique, known in other 3D packages as morphing, is a popular way to animate facial expressions or speech. |
Hotkeys to Memorize y Repeat the use of the last tool sometimes called the non-sacred tool. p Parent all selected objects to the last selected object. k+MMB-drag Scrub the Time Slider. |
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