We have proposed the IllusionHole system, which allows three or more people to simultaneously observe stereoscopic images from dynamically changing individual viewpoints. With a simple configuration, this system provides intelligible 3D stereoscopic images free of flicker and distortion. Based on the IllusionHole concept, we have built a prototype system using two liquid crystal projectors and polarizing filters. This paper describes the details of this prototype. We investigate how the image formation position of the stereographic image is affected by sources of errors such as measurements of the user's interpupillary distance and observing position. We also measure and discuss the variation of brightness and hue with viewing direction.

An ideal stereoscopic display system for multiple users is proposed. It allows three or more people to simultaneously observe individual stereoscopic image pairs from their own viewpoints. The system tracks the head positions of all of the users and generates distortion-free images for each eye of each user. The system consists of a normal display and a display mask, which has a hole in its center. The display mask is placed over the display surface at a suitable distance from it. By controlling the position of the image drawing area for each user according to the corresponding user's viewpoint, each user can observe the stereoscopic image pairs shown in an individual area of the display system with shutter glasses. On the other hand, no user is able to see the image drawing areas of the other users because these areas are adequately occluded by the display mask. Accordingly, the display system can simultaneously provide intelligible 3D stereoscopic images for three or more moving observers without flicker or distortion.