Educational Install: 3D Simulation To The Max

CHALLENGE: Update a six-sided virtual reality system to meet today's needs and lead it into the next generation.

SOLUTION: Design a system that employs the highest resolution projectors available and one of the world's largest graphics computer clusters.

IMMERSIVE VIRTUAL REALITY enables a broad range of researchers to overcome challenges posed by space constraints, scale, or time variances. Biologists use it to shrink themselves down to the cellular level. Manufacturers apply it to developing new products and managing business models. The military employs it to train for real-world combat.

At Iowa State University in Ames, Iowa, the Virtual Reality Applications Center (VRAC) is at the forefront of virtual reality technology. In 2000, VRAC opened the C6, the first six-sided immersive virtual reality system in North America. A new variation CAVE design (Cave Automatic Virtual Environment, see sidebar), the C6 is a 10-foot-by-10-foot-by-10-foot room in which computer images are rear projected on soft vinyl screens supplied by Stewart Filmscreen on all four walls and the ceiling. A single 2,000-pound, 2 ¾-inch thick piece of optically-correct acrylic allows images from the bottom projector to appear on the floor. One of the wall screens is mounted on a pneumatically actuated frame to allow for access to the C6.

Likening the 3D virtual reality experience to a very sophisticated version of a child's Fisher Price ViewMaster, in which the circular disk shows one image for the right eye and another for the left, Dr. James Oliver, director of VRAC, says the brain fuses those images together to make them appear three dimensional. “You don't see the edges of the boundaries; the walls just melt away, and objects come at you from outside or go out to infinity, he says. However, this vision is difficult to convey in a photograph or video because it becomes only two-dimensional. “Without the stereo effect, it looks like a big box with lights on the walls,” he adds.

For its first five years, VRAC's C6 was one of most widely used virtual reality systems in the world. But by 2005, Oliver says that every performance dimension of the C6 needed improvement. “It had some unique innovations in its day,” he says. “But five years is a long time in technology.”

Image courtesy of Mechdyne Corp. A diagram of the C6 structure, showing the framework and image overlap requirements.

Securing nearly $5 million in funding from the U.S. Air Force Research Laboratory to upgrade the C6, VRAC set out to solicit bids for the project in mid-2005. VRAC received five bids for the project and selected Fakespace Systems, the display system integration division of Marshalltown, Iowa–based Mechdyne Corp., as the installer for the C6 updates in January 2006. Mechdyne was the original installer on the C6 project in 2000. Updates on the system began in May 2006.

In its detailed functional specifications, VRAC required that the new solution be capable of producing a minimum of 4 megapixels at a resolution of 2000 x 2000 per wall for a density of 16.67 pixels per inch. Knowing that increased resolution was high on the list of priorities, Kurt Hoffmeister, vice president of engineering for Mechdyne, says his company wanted to offer VRAC a solution that far exceeded this minimum requirement.

Fakespace incorporated 24 SRX-S105 SXRD projectors, manufactured by Sony Electronics, in the update. Introduced in July 2006, the SRX-S105 ultra high-resolution projector — one of four units in Sony's SXRD projector series — was specifically designed for large-venue and high-resolution applications. The 4096 x 2160 resolution of this projector is four times greater than the highest definition television currently available to consumers. On the 10-foot-by-10-foot walls of the C6, pixel density is greater than 34 pixels per inch, and with a total 24 projectors, the system achieves a 100 million pixel stereoscopic display, which is 16 times greater than C6's original display. Of the initial $5 million bid, the facility and technology upgrade — including projectors, electronics, and optics — made up more than $3.5 million of the cost.

Fakespace knew that the only way to meet VRAC's resolution requirement and support stereoscopic viewing with the current technology available was to provide multiple projectors per wall. Four projectors were stacked vertically for each surface, reaching about 10 feet high. “Two blend together to make up a 4096 x 4096 right eye image, and because it is stereoscopic, the other two projectors are providing the left eye image,” Hoffmeister says. “Because the projectors have to overlap each other to produce a square image, we're using Fakespace's own version of optical blending.”