Autodesk 12812-051462-9011 User Guide 3 - Page 2732

A big advantage of the footstep method is the natural adaptation of the biped that occurs when the footsteps are edited in time and space. Also, you can reposition all of the footsteps to move the entire animation. Forward Kinematics The default method of manipulating a hierarchy uses a technique called "forward kinematics". The basic principles employed by this technique are: ■ Hierarchical linking from parent to child ■ Placement of pivot points to define the connecting joint between linked objects ■ Inheritance of position, rotation, and scale transforms from parent to child In forward kinematics, when a parent object moves, its children must follow. If the child wants to go off on its own, the parent remains behind. For example, in a hierarchical linkage of a human figure, when the torso (the parent) bends over, the head (the child) moves along with it, but you can turn the head without affecting the torso. Forward Kinematics (Bipeds) Using an arm to move a hand is an example of forward kinematics. Using the hand to move the arm is an example of inverse kinematics on page 8016. When you use freeform animation on page 7988 to animate a biped on page 4147, you can use both kinds of kinematics. By planting a hand or foot, you use another object (object space) or the world (world space) to control IK motion. In this method, the IK Blend parameter in the Key Info rollout on page 4367 determines how forward kinematics and inverse kinematics are blended to interpolate intermediate positions. Frame Rate The frame rate of an animation is generally expressed in frames per second (fps). This is the number of frames displayed for every second of real time. Different recording devices output different frame rates, but the standard rates are as follows: Glossary | 7987