(Disney Meets Darwin)

5 Physics

A qualitative physics model is used to constrain motion in these figures. Although it is quaint and homegrown, this model does produce most of the basic salient features of interacting physical bodies such as falling under gravity, collision effects, and angular momentum. But most importantly, this abbreviated physics model is computationally lightweight enough to allow many figures to be animated simultaneously in real-time (on a Silicon Graphics IRIS workstation). Apprehension of real-time motion is vital for this system, as the animator must be able to evaluate subtle motions on the fly for interactive evolution to be done successfully.

This animation system uses no concept of simulated time as opposed to real-time. Since these figures are not intended to be manufactured as robots, the time it takes for them to animate themselves is all that matters, and it refers to no real-world translation of time. Other physics-based animation techniques incorporate robust algorithms for accurate simulation, and can generate torque effects, etc. But these systems may not afford real-time "intimacy" with a large collection of moving figures, due to the fact that computational demands slow down animation rates, so motion quality can only be experienced after animation frames have been recorded onto videotape and played back at video rates. Physical accuracy has been compromised in this exploration because my chief goal is to understand the nature of interacting with inherently real-time figures. I have found that any resulting inconsistencies with true-world motion are negligible and almost never distract from people's attention to the engaging issues of evolution and the development of a figure's body language.

As physics algorithms become more efficient, and animation hardware faster, more comprehensive physics models can be used in real-time animation systems such as this. However, my future goal may not be more accurate simulation of Newtonian mechanics, but a model fashioned on "cartoon physics", where expressivity, intention, and humor are directly built-in to the laws of physics, encoding the techniques of the master cartoon animators. This set of techniques is sometimes called "Cartoon Laws".

6 Muscles

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