Legde,K., Castillo,S., Cunningham,D.W.
The majority of virtual agents have adult bodies. There are, however, a number of reasons for using younger avatars. For example, an adult interface agent usually leads users to expect adult-level communicational and social skills. As a result, users tend to be rather intolerant when the interface agent makes obvious mistakes (e.g., incorrect grammar) or uses inappropriate behavior (e.g., looking away from the interlocutor). Since computer social-skills are still under-developed, it seems reasonable to use a body model that reflects this: child avatars. Unfortunately, the use of database-driven techniques for creating a variable-aged animation system would require a very large number of scans of children at different ages, making such a system impractical for technical and ethical reasons. As an alternative, this paper develops and validates a method for synthetically and systematically altering the apparent age of a virtual character. Starting with a three-dimensional, adult facial scan, we use a physiologically-inspired, trigonometric polynomial to age-regress the model (and any associated animation) to the desired age. Quantitative measurements show that the technique can reconstruct the correct anthropometric proportions of 2-10 year-old children. A perceptual experiment provides an initial mapping of the technique"s parameters onto the perceived age and realism.