Showcasing augmented reality: a projection-based technology gets more people into virtually enhanced worlds. (techwatch).

One of the long-standing obstacles to successful virtual and augmented reality applications is the difficulty users have of "getting into" the digital environment. Head-mounted displays (HMDs) are plagued by an unbalanced ratio between quality optics (high-resolution, large field of view) and ergonomics factors. Currently, HMDs that provide good quality are heavy and cumbersome, while lightweight HMDs tend to provide low-quality images in exchange for comfort. For augmented reality applications, HMDs suffer further from focal-length discrepancies. In other words, an image that is overlaid on a real object doesn't appear at the same depth as the real object. Depending on the optics used, the images appear at a constant depth in front of the user's eyes. This means that the eyes have to continuously shift focus between depth planes, or view either the object or the digital imagery out of focus.

Conventional projection-based VR systems (walls, workbenches, caves, domes) bypass most of these problems, but they have limitations of their own, including their inability both to support individual view perspectives of multiple users and to integrate real and virtual objects.

In an effort to overcome these problems, researchers at the Fraunhofer Center for Research in Computer Graphics (CRCG), in cooperation with researchers at Bauhaus University in Germany and the Vienna University of Technology, are developing a new projection-based augmented reality display. Called the Virtual Showcase, the high-resolution display environment supports the shared interactive representation of virtual and real objects for individual or multiple users. The researchers' goal is to create a technology framework for "ambient intelligent landscapes," says CRCG scientist Oliver Bimber, "where the computer acts as an intelligent server in the background, and users can focus on their tasks rather than on operating computers."

The Virtual Showcase consists of two parts: a convex assembly of half-silvered mirror beam splitters and a projection screen for graphics display. To date, the researchers have built Virtual Showcases with two different mirror configurations. The first consists of four half-silvered mirrors assembled as a truncated pyramid. The second prototype uses a single mirror sheet set up to form a truncated cone. The mirror assemblies are placed on top of the projection screen. "Users can see real objects inside the showcase through the half-silvered mirrors merged with the graphics displayed on the screen," says Bimber. The contents of the showcase are lit with a controllable light source, while view-dependent stereoscopic graphics are presented to observers wearing standard shutter glasses controlled by infrared emitters. Users' head movement can be tracked using either optical or electromagnetic tracking devices. The pyramid shaped prototype supports up to four viewers, who can view the showcase simultaneously from four different sides. The cone-shaped prototype offers a seamless surround view of the display. Currently, the display graphics are rendered using a single, ...