The CAVE Facility
Texas A&M University at Qatar recently acquired a virtual reality (VR) system known as the CAVE. It is a four-sided space onto which high resolution images are projected. The viewer wears a pair of virtual reality glasses that provide depth perception via a process known as stereoscopy — a technique whereby two slightly offset images are shown to the viewer– one per eye. The viewer's brain ultimately processes the pair of images as one, and senses depth in the image as a result. The images are generated by powerful computers in coordination with a motion capture system which records the viewer's head position and orientation with respect to the projection surfaces. These head movements are factored in to how the rendered images are displayed on the projection surfaces. As a result, the viewer is able to explore her virtual world by moving around the space and even grabbing objects with a flystick, a wand-like device. Multiple viewers often share virtual experiences and easily carry on discussions inside the CAVE, enabling researchers to exchange insights. One user is the active viewer, controlling the stereo projection reference point, while the rest of the users are passive viewers.
The projection system comprises four display surfaces: front, floor and two sides (left and right). Each display surface is rear-projected by a Barco NW-12 projector having 12000 ANSI Lumens at a refresh rate of 120 Hz. The physical size of both front and floor displays is 3.1 x 2.3 meters and the image resolution is 1600x1200 pixels. The size of the left and right side displays is 2.3 x 2.3 meters with an image resolution of 1200x1200 pixels. The side display surfaces are configurable and support four different geometries: power-wall, immersive-theatre, L-shaped and CAVE. First, the power-wall geometry presents a large ultra-wide display that is suitable for collaboration, project review and presentation to a typically large audience. Second, the immersive-theatre arranges the side displays at 30o or 45o angle from the front display. It is typically suitable for collaborative work when a partially immersive environment is needed. Third, the L-shaped geometry is a combination of both power-wall and immersive-theatre geometries that configures one side in a flat-screen geometry and the other in fully closed configuration giving an L-shape configuration. And last, the CAVE-like geometry provides full immersive experience to the users. The system has two image generators. The first is a cluster of five powerful HP Z820 workstations – one master and four slaves. Each workstation contains a dual Intel Xeon E5-2690 @2.40Ghz processor having 8 cores each, 32GB of system memory, 4TB of disk space and one Nvidia Quadro K5000 graphics card with 4 GB of GDDR5 graphics memory. The cluster is interconnected with a 10GigE network and is gen-locked with each other to synchronize the output images in order to avoid image tearing. The graphics cluster is used to drive the system in the CAVE (closed), L-shaped and immersive-theatre configurations when all four displays are active -- each slave workstation drives one display separately. The second image generator is a single workstation that is also an HP Z820 system but with a more powerful graphics configuration (Nvidia Quadro Plex configured in SLI Mosaic mode). It drives the system in the flat-wall configuration giving users an ultra-wide desktop. In this mode, the floor projection is switched off. Both image generators run on the 64-bit Windows 7 operating system. In addition to the immersive visualization capabilities, the facility also has a Blu-ray player for full HD 1080p video playback, and a user laptop input port with support for 5.1 channel surround sound.