Emotions for a motion: rapid development of believable pathematic agents in intelligent virtual environments

Abstract

This paper discusses and proposes a solution for two interrelated problems: how to develop real-time intelligent virtual environments with believable agents over short periods of time, and how to instill emotional believability in these agents. Short development time is achieved using a modular architecture approach, minimizing the communication between modules, and therefore allowing their parallel implementation. Real-time performance is achieved using information redundancy and one-way communication between modules. All these techniques are supported by a theatrical metaphor. The intelligent virtual environment is divided into three functional units: the dynamic scriptwriter who creates the narrative, the theatrical company and its cast of actors who perform upon it, and the virtual stage managers who handle the cameras and special effects. The dynamic scriptwriter is responsible for the management of the synthetic actor inner persona. Personality is expressed as a regular exteriorization of emotions. Thus, the synthetic characters are characterized by a set of valenced reactions exteriorizing their inner goals, beliefs, and attitudes. The emotional structure is handled by an instantiation of Ortony, Clore, and Collins' cognitive theory of emotions and the agent implementation is inspired by Frijda's two-stage emotional stimuli appraisal theory. This approach was tested in a real-time application developed under a tight schedule, and exhibited in Lisbon during the last world exposition of the century, Expo'98. Two synthetic dolphins, the emotional characters of this intelligent virtual environment, were displayed to more than one million visitors over the four months of the exhibition. This project showed that the approach is a viable solution for short time development of quality intelligent virtual environments. © 2000 Taylor and Francis Group, LLC.