Virtual Reality Laboratory

Virtual Reality Research Group


Computers, tracking and graphics

The lab uses two high-end PC workstations to generate virtual scenes in real-time as an observer moves.

To track an observers movements we use a 14 camera Vicon tracking system (MX3 and T20S cameras). These are connected to the labs tracking computer. The sole role of the tracking computer is to run the Vicon Tracker software. This outputs the coordinates of the HMD and other tracked objects at 240Hz.

The tracking computer has a Quad-Core Intel Xeon 3.6GHz CPU, NVidia Quadro K2000 graphics and 8GB RAM. This is connected to the labs main graphics computer by gigabit Ethernet.

The graphics computer generates the simulated environment in real-time with an eight core AMD Opteron 6212 CPU, dual NVidia GeForce GTX 590 graphics cards and 16GB RAM. 

Both computers run the Windows 7 operating system. 

Virtual environments are generated using custom code running in Matlab using the Psychtoolbox extensions. Coordinates are polled at 60Hz (the refresh rate if the HMD) using the Vicon DataStream SDK for Matlab. The coordinates are then used to generate the virtual scene in Matlab using the Psychtoolbox extensions.

Psychtoolbox is based on C/C++ and OpenGL, and allows virtual scenes to be geenrated with 32 ms end-to-end latency, with a static positional accuracy less than 1mm.

 

Displays

nVisor SX111The main display headset is the nVisor SX111 which offers a binocular view overlap of 50 degrees, with a total horizontal viewable region (binocular + monocular) of 102 degrees. This wide area is necessary since many human vision phenomena are based on information from the peripheral non-binocular region of view.

The SX111 uses LCD displays with a resolution of 1280x1024 pixels, which equates to about 3.6 arcmin per pixel (76 deg per eye). We calibrate the HMD using our in-house calibration method Gilson et al (2008) and Gilson et al (2011).

In the past we have used a CRT-based nvision DV80 headset.

 

KEO headsetFor really high resolution work, the lab also has a KEO ProView. This has 1024x768 pixels over a 35 degree (diagonal) image area of giving 4.8 arcmin resolution.

 

 

 

 

Additional Tracking

In addition to the Vicon tracking system discribed above, the lab also has a number of additional tracking options. 

An Intersense IS900 Large Area Tracking system, uses ultrasound and inertial sensors to determine the position and orientation of trackers within the lab. Presently, the system covers a 3.5x3.5x3m volume, and has one head-mounted station and two hand stations (wands).

There are also ISCAN headmounted eye tracking systems, which are able to track eye position and line of sight in realtime, even when the subject is wearing a headset.

Finally, for detailed tracking (but only over a small area), we have a Polhemus FASTTRAK magnetic tracker.

 

Video capture

We have a range of cameras available for calibration and motion analysis purposes:

Pike F-145BAn AVT Pike F-145B camera. This has a 1388x1038 resolution with a wide field of view lens, making it ideal for HMD calibration.

 

 

 

Basler A600fcFor motion tracking, two Basler 602fc cameras are used. These can stream VGA resolution (640x480 pixels) images to the host computer at 100 frames per second, where home-grown software saves the frames to disk for later processing.

 

FIRE i400We also have a pair of UniBrain FIREi400 IEEE1394 digital video camaras for a similar purpose.

 

 

 

 

Other equipment

The lab is equipped with a range of conventional desktop PC's and laptops. These run Windows, OSX and Linux Ubuntu. Data is backed up using GNU/Linux-based fileserver with Sony AIT2 backups.

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