Greta: A Simple Facial Animation Engine Stefano Pasquariello 1 , Catherine Pelachaud 2 1 Kyneste S.p.A, Rome, Italy 2 Department of Computer and Information Science University of Rome “La Sapienza", Rome, Italy Abstract. In this paper, we present a 3D facial model compliant with MPEG-4 specifications; our aim was the realization of an animated model able to simulate in a rapid and believable manner the dynamics aspect of the human face. We have realized a Simple Facial Animation Engine (SFAE) where the 3D proprietary facial model has the look of a young woman: “Greta". Greta is the core of an MPEG-4 decoder and is compliant with the “Simple Facial Animation Object Profile" of the standard. Greta is able to generate the structure of a proprietary 3D model, to animate it, and, finally, to render it in real-time. Our model uses a pseudo-muscular approach to emulate the behaviour of face tissues and also includes particular features such as wrinkles and furrow to enhance its realism. In particular, the wrinkles have been implemented using bump mapping technique that allows to have a high quality 3D facial model with a relative small polygonal complexity. 1 Introduction MPEG-4 is an ISO/IEC standard developed by MPEG (Moving Picture Experts Group), the committee that also developed the well known standards MPEG-1 and MPEG-2. MPEG-4, whose formal ISO/IEC designation is ISO/IEC 14496, was finalized in October 1998 and became an International Standard in the first months of 1999. The fully backward compatible extensions under the title of MPEG-4 Version 2 were frozen at the end of 1999, to acquire the formal International Standard Status early 2000. Some work, on extensions in specific domains, is still in progress. MPEG-4 provides the standardized technological elements enabling the integration of the production, distribution and content access paradigms of: digital television, interactive graphics applications (synthetic content) and interactive multimedia (World Wide Web, distribution of and access to content). Among other items, MPEG-4 defines specifications for the animation of face and body models within a MPEG-4 terminal [4, 9]. We realized a Simple Facial Animation Engine (SFAE) that has the look of a young woman: “Greta”, it is the core of a MPEG-4 decoder and it is compliant with the “Simple Facial Animation Object Profile” defined by the standard.