An Immersive Projection Technology (IPT) has been noted as a display device for virtual reality. In this system, users enter a space surrounded by multiple screens, and it projects stereo images matching the position of one user. When multiple users observe them, images matched one user are projected. Therefore, all users observe the same images. Our aim of this study was to make two users observe different 3D images at the same time. In this research, we proposed a system that uses real-time tracking and four parallaxes projection corresponding to two users using LC shutter glasses and a 3D projector. We conducted experiments to confirm whether two users can observe different 3D images at the same time. In experimental results, it was confirmed that the corresponding parallax images could be seen with the eyes of two users and that it was possible to track the position of the two users. This made it possible for two users to observe different 3D images at the same time.
In a short period of time, virtual reality has taken over the media, tending to promote that idea that it is a new technology. In fact, all started as early as the seventies and eighties, for portable devices (e.g.Head-Mounted Displays) as well as for complex and large devices (CAVEs). In this paper, we try to put these different systems in perspective, and to show the interest of comparing them in an experimental approach.