NAVE Parts List

The NAVE uses three VREX 2210 stereoscopic projectors.   These projectors have a mono resolution of 1024x768 at 400 Lumens.  Because the NAVE is enclosed in a completely dark, windowless room, 400 lumens was sufficient.  VREX sells stereoscopic projectors that cost between $8000 and $15000 each.  If you are interested in these projectors, our contact at VREX is Carl Tung (tung@vrex.com).  Our sales representative is David Harrison (harrison@vrex.com).

There are also several models of affordable mono LCD projectors on the market offered by Epson, 3M, and Phillips which cost between $3000 and $12000.  Prices vary depending on resolution and brightness.  Replacement bulbs can cost as much as $1000 making bulb life an issue to consider.  Barco and Electrohome provide impressive, high-end projectors with stereo capabilities.  These projectors are used in the CAVE, Immersadesk, and Immersive Workbench systems.  However, the prices can approach $40000 making their cost prohibitive.
 

Currently our application runs optimally using cards based on the NVIDIA RIVA TNT2 chipset.  A number of firms including Creative, Diamond, and Hercules offer RIVA TNT2 based products.  These cards provide excellent OpenGL and Direct3D hardware accelerated performance.  These cards can be purchased for as low as $150.00. We have found that the drivers work equally well for Windows NT and 95/98.  Using these cards, the Santiago 2000 Virtual City runs in stereo with 15-25 fps, at 1024x768 resolution.  For our applications, we have found that these cards often outperform high end SGI graphics workstations and expensive PC OpenGL accelerators.  The lucrative 3D game market has resulted in the emergence of incredible price/performance ratios in PC graphics products.

Evans and Sutherland offers high quality graphics accelerators supporting dual screens and stereo viewing though these cards are priced as high as $2000 each.
 

For real time 3D (positional) audio capabilities, our audio API requires a sound card with four speaker output and DirectSound3D hardware acceleration capabilities.  The Diamond Monster MX300, and the Soundblaster LIVE! have these features.  These cards can be found for as low as $100.  Basic 3D sound can be  programmed using Microsoft's DirectSound SDK.  Hardware acclerated 3D audio using DirectSound3D is only available in Windows 95/98.  NT provides software accelerated 3D audio which is woefully insufficient for creating a convincing 3D audio environment.  Consequently, the audio PC in the NAVE system runs Windows 98.  Windows 2000 (aka NT 5.0) supposedly resolves the descrepancies between 95/98 and NT.
  Low quality speakers can significantly hinder the benefits of audio cues in a virtual environment. The best speaker solution in terms of size and versatility is the Bose Acoustimass-6 system.  The system includes 5 small cube speakers and a passive subwoofer.  Two of the cube speakers were mounted on the top corners of the center screen providing the front left and right channels.  The front speakers were oriented downward toward the two user seats.  Two other cube speakers were mounted on stands behind the seats at the approximate ear height of a seated user.  The passive subwoofer was placed in a corner of the room to maximize its effectiveness.  The fifth cube speaker is not used by the NAVE audio system.  The Bose Acoustimass 6 system can be purchased for $700.00.  Crutchfield offers Bose products online.
  Aura systems manufacturers the "Bass Shaker Pro" which can be mounted under seats or platforms to create bass vibrations.  The bass shakers can be purchased for approximately $150 per pair.  Six bass shakers are installed in the NAVE floor.  In the NAVE audio system, a second four channel sound card is installed in the audio PC.  The six bass shakers and the subwoofers mounted under the user seats are subdivided into four zones.  The second audio card exclusively steers four channels of discrete bass across these zones.  Consequently, it is possible to convincingly create audio-tactile effects for simulating the vibration of vehicles, thunder, explosions, shockwaves, and earthquakes.
  Four audio amplifiers are used in the NAVE. Each of the four Bose cube speakers requires a discrete amplifier channel.  To satisfy this requirement, two Pioneer SX-205 stereo amplifiers capable of outputting 100 watts per channel are employed.  One stereo amplifier drives the front left and right speakers.  A second stereo amplifer drives the two rear speakers.  The four outputs of the Soundblaster LIVE! are connected to these two amplifiers.

The four bass zones require two additional Pioneer SX-205 amplifiers which are connected to the Monster Sound MX-200´s four outputs.

The four amplifiers cost $100.00 each.

The NAVE uses custom cut plastic rear projection screens that preserve the polarization in the VREX image.  Our three screens were purchased directly through our VREX sales representative David Harrison (harrison@vrex.com).  The screens used for the NAVE prototype cost approximately $1000.00 each.

In Santiago de Compostela, Spain, the screens were obtained through a local plastics company.  Sample test materials were obtained from the plastics firm.  The samples were tested with the VREX projector to determine the best material to use.  Once a material was selected, the rear projection screens were cut to our specifications.  The plastics company charged approximately $300 for each screen.

Initially, we were convinced that we needed to use front surface mirrors similar to those in reflector telescopes to preserve the light polarization.  We learned that other systems used stretched mylar. Mylar mirrors proved difficult to obtain.  We decided to test the material used in standard bathroom mirrors.  We purchased a 1 foot by 1 foot mirror tile at a local hardware store.  The tile was 1/4 inch thick, rear surfaced.   It worked perfectly with the VREX projector with no polarization loss.  We took this tile to a mirror and glass cutting firm, and we asked them to cut larger versions.  This company typically provides mirrors for clubs, homes, bathrooms, and department stores.  They cut and sold the mirrors for a total cost of approximately $300.00.  These mirrors were mounted on stands built from 1 inch thick plywood, 4x4, and 2x4 lumber pieces. The initial content for the NAVE, the Santiago 2000 Virtual City, uses the Simple Virtual Environments (SVE) Toolkit.  OpenGVS is a commercially available, cross-platform toolkit that could also be used to author content in a NAVE system.  OpenGVS can be obtained for $2,500 according to their latest price list.
 


Three pentium III 500 Mhz PC´s were used to drive each of the three projectors.  A Pentium II 450 acts as the audio server and master simulation controller.  The PC´s were bought from Dell online.  The four PC´s are linked via an Ethernet network hub.  A digital switchbox allows the four computers to share one keyboard, mouse, and monitor.  The switchbox and connection cables, manufactured by Belkin, cost $300.00

Approximately $2000 was spent on lumber and hardware supplies.  A strobe light for lightning effects cost $30.00 at a party supply store.  Four fans used for wind effects cost lest than $15.00 each.  Another $1500 was spent purchasing video, audio, and power cables.
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