Inverse Kinematics and Geometric Constraints for Articulated Figure Manipulation

Computer animation of articulated gures can be tedious largely due to the amount of data which must be speci ed at each frame Animation techniques range from simple interpolation between keyframed gure poses to higher level algorithmic models of speci c movement patterns The former provides the animator with complete control over the movement whereas the latter may provide only limited control via some high level parameters incorporated into the model Inverse kinematic techniques adopted from the robotics literature have the potential to relieve the animator of detailed speci cation of every motion parameter within a gure while retaining complete control over the movement if desired This work investigates the use of inverse kinematics and simple geometric constraints as tools for the animator Previous applications of inverse kinematic algorithms to computer animation are reviewed A pair of alternative algorithms suitable for a direct manipulation interface are presented and qualitatively compared Application of these algorithms to enforce simple geometric constraints on a gure during interactive manipulation is discussed An implementation of one of these algo rithms within an existing gure animation editor is described which provides constrained inverse kinematic gure manipulation for the creation of keyframes