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The Virtual Reality Laboratory

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Equipment

Haptic Equipment

PHANTOM 3.0 by Sensable Technologies
Our Phantom haptic simulation devices allow the haptic rendering of virtual scenes, i.e. you can touch and feel objects that are not really there. This allows for an unprecedented feeling of immersion in a virtual reality environment and allows the study of visuo-haptic coordination, adaptation, and learning in psychophysical experiments. Our instrument allows us to produce artificial environments with subtle or gross discordances between visual and haptic information which are not attainable in the real world.

Description
The haptic setup consists of two PHANToM 3.0 force feedback devices by SensAble Technologies, Inc. Each device is mounted on a specially made epoxy block. We aligned the two devices with high precision and reduced the mismatch between them below 1mm across the central area of our workspace. The haptic simulation is done on a SGI Onyx 2 or SGI Onyx workstation and runs at a rate of 1 kHz. A graphical user interface allows for quick and easy generation of visuo-haptic scences and design of experiments. The two PHANToM force feedback devices are used in one workspace in order to perform easy one-hand precision grips or two handed pointing tasks. The GUI allows all object properties to be changed on the fly.

Phantom Tutorial and Documentation (UNDER CONSTRUCTION)

Position Sensing Equipment

Hi-Ball Precision Tracker by 3rdTech
The development of the 6 degrees of freedom Hi Ball tracking system allows subjects to walk in a virtual environment with relative ease. The HiBall tracker is a recent development based on the Wide-Area Tracking research project of the Department of Computer Science of the University of North Carolina at Chapel Hill.

Description
HiBall is an analog/optical tracking system that can track the linear and angular motion of a receiver at sub-millimeter spatial and near-millisecond temporal resolution over a large field, making it ideal for measuring movements of VR HMDs. No other device can provide comparable speed and accuracy over a wide area. The system triangulates position using multiple analog sensor/lens pairs to image a number of IREDs on the ceiling. The device can :
  • Provide 2 rooms with 622 sq.ft. and 240 sq.ft of tracking space
  • Maintain extraordinary precision throughout the tracking space
  • Deliver precision unaffected by metal, magnetic fields, noise
  • Built in redundancy overcomes most line-of-sight obstructions
  • Provide very high update rate and low latency - solid tracking even at high-speed motion


Fastrack by Polhemus
The Fastrack is a 6 degrees of freedom magnetic tracking device. The device runs at 120hz with 4ms latency. The primary limitations of this system are its range of 30 inches (without a significant loss in accuracy and its susceptibility to electromagnetic interference.)

Eye Tracking Equipment

ASL 201 Eye Tracker by Applied Science Laboratories
The most recent extension to our eye tracking capability is the inclusion of a separate limbus tracker. Despite it's poor spacial resolution, the superior temporal resolution of the limbus tracker allows for updating the display based on saccadic eye movements.

Description
The limbus tracker is mounted on a goggle-like frame with an elastic strap. Subjects first don the limbus tracker then put on the HMD for use in virtual environments. The limbus tracker's 1000hz sampling rate provides 8 millisecond temporal latency. We are currently integrating it into the experimental control software.

ASL 501 Eye Tracker by Applied Science Laboratories

ASL 501 Online Tutorial and Documentation

This eyetracker is the centerpiece of our psychophysical instrumentation. The VR Lab was the first laboratory worldwide to install eye-trackers into an head-mounted display (HMD) providing the capability to track the eyes in a virtual environment.

Description
The ASL 501 was recently upgraded to the 5000 series. The tracker, which is mounted within the optics of our V8 HMD, runs at 120hz. In addition to the HMD system, we are also able to use the ASL to track real world tasks. We have developed a system for recording the image of the observer's eye and overlaying this on the video record containing the location of gaze. This allows better evaluation of small eye movements and allows us to minimize the effects of tracker noise in our data.

ASL 501 Mobile Eye Tracker by Rochester Institute of Technology
The mobile eyetracker allows exploration of eye movements in real world tasks and environments. This tracker was built by Rochester Institute of Technology in collaboration with ASL.

Head Mounted Displays

V8 Helmet by Virtual Research
The V8 Helmet is a stereo display used to visualize our virtual environments. It contains an ASL 501 eye tracker and can be used with the limbus tracker at the same time. Head position is monitored by either the HiBall or Fastrack devices.

Description
Each of the V8's 1.3 inch LCDs runs at true VGA (640x480) resolution with 921,600 color elements. The active matrix displays, which are driven by an external control box, refresh at a rate of 60hz. Field of view is 60 degrees diagonal. The helmet allows for adjustment of interpupilary distance. Sound is provided by a pair of Sennheiser headphones. Each V8 weighs approximately 1kg.

Computing Hardware

Onyx 2 Visualization System by SGI
The Onyx 2 is now the primary system used for running experiments. It is equipped with 4 MIPS R10000 processors running at 300MHz. Graphics are rendered by an Infinite Reality 2 graphics engine. Video for the HMD is output at 60Hz.

Onyx Visualization System by SGI

Other Computers
G3 by Apple
G4 by Apple
O2 by SGI
Athlon by AMD
Pentium 3 by Intel
Pentium 3 Xeon Dual Processor Dell Workstation by Dell

Driving Simulation

Motion Platform by McFadden Systems
The motion platform is a hydraulic system capable of 6 degrees of freedom. The platform is controlled by a dedicated PC running software from the manufacturer.

Driving Console by Simulator Systems Int., Inc.
The driving console contains the accelerator, brake and steering inputs from the driving simulator. Inputs are converted from analog to digital in an a2d converter before being processed. The console is equipped with subwoofer-like tactile sensation devices to produce vibrations in the driver's seat.

3D Digitizing

Vivid 900 by Minolta
This high-resolution 3D scanner from Minolta uses LASER triangulation to form 3D models of objects. Multiple exposures can be merged together to form complete 3D representations.

Description
The Vivid 900 uses a 1/3" 340,000 pixel CCD for image capture. Internal automatically-switched color filters are used to apply textures to 3D models. Scanning takes 2.5 seconds to capture 307,000 points and an additional .5 seconds for capturing color information with resolutions up to 0.039 mm. Software on a Dell Dual P3 Xeon workstation is used to merge multiple exposures for more complete 3D models. 3D models can be output to VRML files.

Video Equipment

Hi-8 VCR by Sony
Hi-8 VCRs have been the workhorses for video recording in the lab.

Mini-DV VCR by JVC
The addition of a DV VCR has brought the lab up to a new level of high-resolution digital video recording. The new format offers the digital benefits of lossless dubbing along with an IEEE 1394 Firewire port. Firewire allows easy video transfers to our PCs and G3/G4 systems for simple editing and distribution.


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Last Updated October 2001 by Evan Gaines