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VR Interfaces: Star CAVE


Overview of Star CAVE

The Star CAVE is the first of the third generation of CAVE VR interfaces - Computer Augmented Virtual Environments.

As its name suggests, it is star-like in that it has five corners, like an pictographic star. However, the outline of its form resembles a pentagon, not a pentagram.

Drawing from the principles of cycloramas, StarCAVE also improves on both its predecessors, by diffusing where the walls meet the floor. Previous CAVEs have used a single back projected screen for each wall, creating a sharp angle where wall and floor meet. Instead, this interface uses three back projected screens per wall.

The middle screen is as before, perpendicular to the floor. Above and below it, are screens which tilt inwards bt 15 degrees, provinding a smoother transistion between wall and floor or wall and ceiling. In total, seventeen screens are thus used. Fifteen screens make up the walls, one for the floor and one for the ceiling, all controlled by the same VR computer system and working in harmony with one another to create a single seamless display.

These displays are backlit by thirty-four high-definition projectors, with two backlighting each screen in an interlacing pattern to provide stereoscopy. One projector on each screen is projecting for the left eye, one for the right eye. Rather than the traditional dedicated minicomputer, this CAVE utilises grid computing, via a network of dedicated PCs. Ech pair of projectors is powered by a high-end, quad-core PC running on Linux, with dual graphics processing units and dual network cards to achieve gigabit Ethernet or 10GigE networking.

The graphics cards in those PCs are using 34 of the newest nVIDIA chips that can generate highly complex images. Each PC has as much high speed memory as its systems can handle, packed to the rafters to speed computation. With this set-up, each projector delivers a 4,000,000 pixel display area to its screen. That means a total of 4,000,000 pixels, per eye for each screen as the projectors are tuned slightly out of phase with one another. Combining all the screens together, that gives a total resolution of 68,000,000. For comparison, the maximum image processing of the human eye at peak, is estimated at 72-78 million pixels.

Thus, the StarCAVE supports 20/40 vision and the images are very high contrast, thanks to the room?s unique shape and the polarised projectors which allow polarised viewing glasses - advanced, unpowered shutter glasses - to view all images in true 3D.

Adding to the experience inside the StarCAVE is the surround sound system, which harnesses recent advances in wave field synthesis ? a way to maximise the perception of many channels of sound emanating from different sides of the room. The developers worked closely with Meyer Sound, Inc., to customise the installation of three arrays of five conventional high-quality speakers to provide 5.1 surround sound or up to 15 channels of discreet audio diffusion (with a subwoofer channel built into the floor structure).

As with previous CAVE structures, a Wanda, or 3D pointer will work just fine as a remote to control the display system, acting as a six degrees of freedom mouse within the thin air in the middle of the CAVE.

While the StarCAVE was in development, computer scientists were working on new applications to adapt computer programs for display in the VR environment. The room connects to the Protein Data Bank, so users can pull up one or multiple proteins and fly around them to find similarities and differences between the proteins. It was constructed by the UC San Diego division of the California Institute for Telecommunications and Information Technology (Calit2), and so a virtual replica of Calit2?s headquarters building at UC San Diego, Atkinson Hall, has been used by neuroscientists who want to know if the human brain operates differently in virtual reality versus reality in ?wayfinding? situations.

While the StarCAVE is already being used by a variety of scientists at UC San Diego, Calit2 will continue to make upgrades to the system to provide even greater realism for users. Eventually the engineers hope to increase the visual acuity from 20/40 to 20/20, by upgrading the system?s 34 projectors from 2K to 4K (roughly 4,000 horizontal pixels for each of the 17 screens) ? an upgrade that could cost at least 3 million USD at today?s prices.

Total expenditure to date, is less than 1 million USD.

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