Virtual Characters

In the VECG group, we have a considerable history of research into how to polulate our virtual enivironments with human like characters. These characters might be entirely virtual, controlled by computer, or they might be avatars, representing real people in a collaborative environment. The scale of our populated environments range from large crowd simulations to one-on-one conversations. Our work mostly falls under two broad research questions: what is it about a virtual that makes believable? and what computational techniques can be used to create believable characters?

As with much of our research in virtual environments we do not uncritically assume that high levels of realism are neccessary for creating believable characters. Instead our aim is to investigate exactly which features of a character create believablity, what is it that makes a cartoon character like Bugs Bunny more compelling than a very much real, but wooden, B-movie actor. To this end we have performed many experiments with a variety of different virtual characters. These experiments show that fairly unrealistic characters can produce strong emotional responses in the right context. Some results even suggest that graphical realism can be detrimental if the characters behaviour is not simiarly realistic. Our current hypothesis, based on these experiments, is that one of the most important aspects of a character, is the simulation of social cues, and in particular non-verbal communications (often called "body language").

This raises the question of what compuational techniques to use to create characters with believable non-verbal communication. We have created characters that can use a number of different modalities for social and emotional expression, including gaze, posture, gestures and facial expression. We have developed an open source animation system, PIAVCA, that supports these forms of expression. We have investigated two main methods for generating non-verbal communication. The first is theory driven, using knowledge obtained from psychology and related disciplines to craft behavioural algorithm. More recently we have been investigating methods that centre on capture and statistical analysis of an actor's performance.

Group members working on Virtual Characters include:

Marco Gillies

Vinoba Vinayagamoorthy

Yip Wong

Sylvia Pan

William Steptoe