How a virtual agent should smile? morphological and dynamic chacteristics of virtual agent's smiles

A smile may communicate different meanings depending on subtle characteristics of the facial expression. In this article, we have studied the morphological and dynamic characteristics of amused, polite, and embarrassed smiles displayed by a virtual agent. A web application has been developed to collect virtual agent's smile descriptions corpus directly constructed by users. Based on the corpora and using a decision tree classification technique, we propose an algorithm to determine the characteristics of each type of the smile that a virtual agent may express. The proposed algorithm enables one to generate a variety of facial expressions corresponding to the polite, embarrassed, and amused smiles. © 2010 Springer-Verlag Berlin Heidelberg.