VIRTUAL ACTORS

Virtual actors and a virtual script
Research area Intelligent Multimedia Systems

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Basis
The history of animated films is even older than that of films. Hand-drawn stroboscopic wheels form the foundations of today's TV and video technique. It takes a lot of work to achieve the fascination of a Walt Disney trick film. Each of the 24 pictures per second that cause the illusion of movement is produced by hand.

Today computer animation saves the animation artists a great deal of graphic work. It produces a mixture of tricks in real films - such as the dinosaurs in "Jurassic Park" - and of real elements in trick films, such as the dancing scene in "Beauty and the Beast". But the most stimulating elements for the films are men, animals, and all kinds of beings from this and other worlds. They are far more animated than any gesture, but they have to be added by the laborious scanning of a real scene rotoscoping.

Living geometry
Virtual actors are different. They are interactive, that means they can be revived easily by cooperation between the animation drawer and the actor. Moving their lips automatically and synchronously to language, virtual actors take over a lot of the burdensome routine work. Moreover they have the ability to remember frequent gestures and attitudes, which can spontaneously be performed by a puppeteer.

Virtual actors in real time
The most important feature of the computer-generated actors is their realtime ability. This is the only way to realize the spontaneous production of several minutes of computer animation for programmes such as "Traugott" broadcast by the Vox channel. Real time allows the use of true-to-life characters in virtual worlds, in interactive artistic installations, and in educational systems.

The virtual script
Never-ending patience, along with unchanging accuracy, is another characteristic feature of the virtual actor. Producers, camera men, cutters, and actors have the possibility of watching a scene from any position desired over and over again. They can alter details and try different cutting sequences. So students can do their experiments without TV studios or filmlabs. Producers will plan entire films in advance; unnecessary and subsequent shooting days can be reduced if not completely avoided. Camera men, together with cutters, can work out cutting sequences or camera perspectives and optimize them without any great outlay.

Further applications
Moreover, virtual actors can be brought into play in TV and cinema films (stunts, cartoons, fancy beings, presentation of telephone partners), in games (adventure games, simulation, cybersex ), in medicine (cosmetic surgery, anatomy) in simulation (drive simulator, risk of injury at gadgets, positioning of operation elements), in communication (face-to-face telephone), and in the arts (interactive element).

Technical realization
Software for the creation and movement of virtual actors has been realized under "C" supported by "GL" on Silicon Graphic Computers. Another C++ module playing (back) completed animations allows problem-free integration into "Inventor"-based programs. Further details can be imported into the actor's world by an interface with "Softimage". Heads or bodies to be adapted or alienated can also be exported on this way. All modules under a "Motif"-interface are now being collected to make them available fo the entire UNIX world.

Matthias Melcher (Kunsthochschule für Medien, Kön), Monika Fleischmann
German National Research Center for Computer Science - September 1994

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