C4 Public Tour group experiencing the popular Fire Cave (Cueva de fuego) VR applicationThe C4, slated for dissassembly in the Spring of 2010, is an early Mechdyne Flex™ system that uses a top-projected floor and rear-projected front and side walls to create an immersive, synthetic environment that supports multiple screen configurations. This facility functions as a "U-shaped" CAVE ™ and is easily reconfigured as 36' wide by 9' high power wall by swinging the movable sidewalls out by 90 degrees.

The C4 simulated environment has been driven by a variety of systems, including

  • An Onyx rack system with 16 MIPS R10000 CPU's, 1792 Mb of RAM, and 3 InfiniteReality graphics pipes.
  • An Onyx2 rack with 24 MIPS R12000 CPU's, 12Gb RAM, and 6 IR2 graphics pipes.
    and currently
  • A four node Linux/Windows dual-boot graphics cluster.

The C4 and the C6 are linked by dedicated fiber running between the SELAB (location of the C4) and Howe Hall (home to the C6), enabling C6-to-C4-based research collaboration among geographically separate virtual reality systems.

To make way for the installation of the Flex ™ system in 2002, the C2, which debuted in the SELAB in October 1996, was mothballed and the space renovated. Changes to the facility included removing old wind tunnel equipment, enclosing openings in the roof, raising portions of the existing ventilation system, leveling and tiling the floor, re-painting, and installing overhead cabling trays.

How Does It Work?
The C4 is comprised of four stereoscopic (three-dimensional) projection surfaces and a three-dimensional sound system. With this system, a user is able to navigate through and manipulate virtual worlds and even connect with users in other simulated environments. The user stands in a 12 by 12 foot arena with rear-projected screens to the left, right, and front. The floor is projected from overhead. Because space is a limitation, the images from the projectors are reflected off of a series of mirrors before reaching the screens (folded optics). The mirror for the floor is mounted near the front of the structure so that any shadows are cast behind the users and out of their normal field of view.

Motion Star (magnetic) or A.R.T. (IR - infrared) tracking systems are used to monitor the user's position and orientation. This maintains the user's correct perspective which is used to calculate a true stereoscopic view as one moves into and around objects that appear within the virtual space. The system also tracks the location of various input devices, such as wands and gloves. Stereoscopic perception is achieved using light-weight Crystal Eyes and NuVision shutter glasses. Three dimensional sound is used to add additional depth to the immersive environment.

* C4 installation and initial research is made possible through the support of the Airforce Office of Scientific Research, with additional funding and support for renovations provided by the Iowa State University Institute for Physical Research and Technology (IPRT) and VRAC.