MARC: a framework that features emotion models for facial animation during human–computer interaction

Emotions and their expressions by virtual characters will play a key role in future affective human–machine interfaces. Recent advances in the psychology of emotions and recent progress in computer graphics allow researchers to animate virtual characters that are capable of subtly expressing emotions. Existing virtual agent systems are nevertheless often limited in terms of underlying emotional models, visual realism, and real-time interaction capabilities. In this paper, we explain how we explored four computational models of emotions that are oriented towards interactive facial animation. The models that we implemented correspond to different approaches to emotions: a categorical approach, a dimensional approach, a cognitive approach, and a social approach. We explain how we implemented and evaluated these models in our Multimodal Affective and Reactive Character framework. MARC is designed for animating interactive expressive virtual agents with different levels of interactivity. The advantages, drawbacks and complementarity of these approaches are discussed.