Computer Animation: a Key Issue for Time Visualization

This paper discusses the relationship between Computer Animation and Visualization. It shows how Computer Animation methods may help to understand physical laws by adding motion control to data in order to show their evolution over time. It presents the state-of-the-art in Computer Animation, emphasizes new trends like physics-based animation, behavioral animation and VR-based animation. New advances in research at the University of Geneva and the Swiss Federal Institute of Technology are presented. keywords: animation, visualization, simulation, motion control, physics-based models, behavioral animation, Computer animation methods may help to understand physical laws by adding motion control to data in order to show their evolution over time. Animation techniques can help increase the scientific knowledge of phenomena and much experimentation should be done in this direction. It is necessary to move from traditional data analysis to the research of more complex structures and to study their meaning in a temporal evolution. When this evolution is not known from the scientist, it is necessary to use traditional computer animation techniques. Visualization has become an important way of validating new models created by scientists. When the model evolves over time, computer simulation is generally used to obtain the evolution of time, and computer animation is a natural way of visualizing the results obtained from the simulation. By using computer animation, scientists may better understand how various phenomena evolve in space and in time. There is another trend in the relationship between animation, simulation and visualization: research in Computer Animation tends to find physical models to improve the motion. To achieve a simulation, the animator has two principal techniques available. The first is to use a model that creates the desired effect. A good example is the growth of a green plant. The second is used when no model is available. In this case, the animator produces "by hand" the real world motion to be simulated. Until recently most computer-generated films have been produced using the second approach: traditional computer animation techniques like keyframe animation, spline interpolation, etc. Then, animation languages, scripted systems and director-oriented systems were developed. In the next generation of animation systems, motion control tends to be performed automatically using A.I. and robotics techniques. In particular, motion is planned at a task level and computed using physical laws. This means that research will tend to find physical models to improve the animation. The main purpose is not a validation of the physical models, but to obtain a graphics simulation of the motion as realistic as possible. We deal with physical objects that are characterized by a shape and dynamics properties. Results have been obtained in modeling rigid objects , deformable and flexible objects (Fig.1) or even set of living creatures and there are examples of their behavior under different circumstances (e.g.