Interaktive Medien - Human Factors Publikations - Pastoor: 3D Displays

3D Video-Communication

Siegmund Pastoor, In Schreer, O., Kauff, P., Sikora, T. (Hrsg.), 2005. Wiley Verlag

13.1 Introduction
Stereoscopic 3D displays provide different perspective views to the left and right eye. Like in natural vision, the differences in perspective are immediately used by the visual system to create a vivid, compelling and efficient sensation of depth in natural and computer generated scenes. Thus, stereoscopic displays not only add a unique sense of naturalness to any video communications system; they are an absolute must if applications require seamless and accurate mixture of video output with real 3D environments (see Chapter 14). Various human factors experiments with advanced display technologies (including large-screen HDTV and 3DTV) have demonstrated that stereoscopy significantly enhances the spatial impression, telepresence and attractiveness of videoconferencing systems. It was concluded that 3D can be considered the promising feature of future videocommunication (Suwita et al., 1997).

Apart from videocommunication, 3D displays have proven to be particularly useful in applications where immediate and accurate depth perception is vital. Remote control of vehicles and robotic arms in hazardous environments as well as handling and coordination of instruments in endoscopic (minimally invasive) surgery are most obvious examples. Various medical applications including diagnosis, surgical planning, training and telemedicine benefit from the visualization of imaging data, such as MRI/CT scans, in full-3D. Room-sized virtual 3D environments like the CAVE system provide total immersion into the world of scientific data. Such surround displays are efficiently used in education, engineering, and scientific computing - both as stand-alone devices and as networked systems for tele-cooperation. 3D displays are increasingly employed in engineering applications like computer-assisted design (CAD) and manufacturing (CAM), genetic and pharmaceutical engineering (modelling of complex protein molecules, structure-based drug design), virtual design review of new products, virtual prototyping, and architecture. Consequently, most renowned 3D software tools already come with special plug-ins for the different stereo formats of today's display hardware. Emerging 3D applications in the military and security fields vary from battlefield simulation to surveillance, intelligence analysis, and baggage scanning. Due to the availability of affordable displays and production technologies the use of 3D displays is spreading out into the domains of entertainment and infotainment (3DTV, 3D film, 3D video, arcade games), trade (electronic show rooms, point-of-sale product presentation with interactive 3D kiosk systems) and education (museums, simulator-based training, teaching).

There are two basic approaches in the underlying 3D display technologies. One relies on special user-worn devices, such as stereo glasses or head-mounted miniature displays, in order to optically channel the left and right-eye views to the appropriate eye. Such aided-viewing systems have been firmly established in many applications. Another approach integrates the optical elements needed for selective addressing of the two eyes in a remote display device, hence allowing free 3D viewing with the naked eyes. In general, free-viewing 3D displays are more comfortable to the viewer. Since the eye region is not occluded by technical equipment, these displays are particularly well suited for human-to-human video communication. The respective technologies are challenging. Most of the numerous concepts presented in recent years are still under development. Based on an earlier survey (Pastoor and Wöpking, 1997) this chapter reviews the state-of-the-art of both, aided-viewing and free-viewing techniques.

The next section will briefly introduce the relevant perceptual processes and definitions needed to understand the basic display concepts. This is followed by a classification of 3D techniques. The main part reviews the basic forms of display implementation. Interested readers find detailed treatises on the foundations of 3D displays and spatial vision in the works of Valyus (1966), Okoshi (1976), and Howard and Rogers (1995).