The present invention relates to a method for generating animations of a human figure modeled by a multi-articulated structure in computer graphics (CG) and, more particularly, to a method for generating animations of shoulder rotation and arm swing of a human figure modeled by a multi-articulate d structure constructed by rigid bars or sticks connected or joined by joints, a recording medium having recorded thereon the method and an animation generating apparatus using the method.
In conventional methods for generating human figure animations, it is customary to model human arms, legs, body, head and so forth as multi-articulated structures constructed from rigid links coupled by joints just like a robot arm. In this instance, the position and direction of each link are represented by polar or cylindrical coordinates parameters or Euler angles. In a D-H method (Denavit-Hartenberg method), a joint-link parameter of an i-th link in a multi-articulated structure constructed by plural links sequentially coupled by joints is represented by Joint.sub.i =[a.sub.i,.alpha..sub.i,d.sub.i,.theta..sub.i ] to express link motions (K. S. Fu. et al, "ROBOTICS:Control, Sending, Vision, and Intelligence," McGraw-Hill, 1987). In either case, the method for generating animations of various parts of the human body by the use of such parameters utilizes (1) an interpolation scheme that employs linear or elementary functions, (2) a scheme that formulates an equation of motion and performs numerical calculations to satisfy initial and final conditions, or (3) a scheme that uses motion data obtained by extracting feature parameters of joint positions in the human body from an image taken by a video camera or measuring positional changes of the human body by a magnetic or electric sensor.
The creation of animations through the use of these parameters requires skill and is low in operation efficiency because it is hard to judge how these parameters directly (visually) contribute to the magnitude or direction of, for instance, arm or leg motions, or because the individual parameters cannot directly be controlled, or because it is difficult to control a motion generating method for each parameter.