Full Body Avatar Interaction Bernhard Spanlang 1,3 and Mel Slater 1,2,3 1 Departament de LSI, Universitat Politècnica de Catalunya 2 ICREA 3 EVENT Lab, Universitat de Barcelona www.event-lab.org Abstract. This paper is a practice and experience paper on the use of a low cost motion capture system. We describe the integration of the Optitrack motion capture system with HALCA a hardware accelerated library for character animation in a Virtual Reality system called XVR. We demonstrate our system by mapping in real-time the tracked whole body motions of a person onto a virtual character which is visualized on an immersive large screen power-wall display. Keywords: Motion capture, character animation, body perception, body scanning. 1 Introduction Since the early days of virtual reality that employed head-tracked head-mounted displays (HMD) the importance of a self-representation, an egocentric virtual body has been recognized – in particular with respect to participant’s sense of presence within the virtual environment. See, for example, [16, 17]. This has also come to be recognized more recently with a new wave of interest in HMDs, for example [10]. A virtual body representation has many applications not only for virtual reality and computer games but even in health care. However, in more common human-computer interaction, such as for computer games such (e.g., Quake) it is normal that no virtual body is required because the interactive images are shown from a first person perspective, and the user does not have head tracking so that it is impossible to look down at one’s own body - although the player may see a virtual body’s (or avatar’s) weapon or hands etc. In virtual worlds such as Second Life 1 or World of Warcraft 2 the player usually can observe his avatar from a birds eye view and control comes from the keyboard, a joystick or other simple interaction devices. More recent hardware for games such as the Nintendo Wii and the Wii balance board have shown new possibilities in controlling an avatar. Here, contrary to the usual hand controlled avatar the user of a 1 http://secondlife.com/ 2 http://www.worldofwarcraft.com