Abstract
In this paper, we define a face plane to a three-dimensional data set of a facial surface and propose a method to capture as two-dimensional data effectively a change of facial expression by using the face plane. We think that such data obtained from a three-dimensional face data set by mapping the three-dimensional face data to a plane located uniquely and stably is more useful for facial expression analysis than the raw three-dimensional face data. The face plane defined in this paper is solved uniquely and stably from a three-dimensional face data set and is located at the position in a head where normal lines to a face surface are focused. First, we give two definitions of the face plane and present a derivation method for each definition. Second, we propose a facial expression differential map which visualizes a facial expression change from a normal face to a smiling or wry face as analyzing method for facial expression. Finally, by a recognition experiment of facial expression, we demonstrate the effectiveness of the face plane and the facial expression differential map for facial expression analysis.
