THE

1
THE WEDGE

• Rod Boswell, Peter Alexander
• Plasma Research Laboratory,
• Research School of Physical Sciences and
  Engineering,
• Henry Gardner, Dave, Hugh, Rhys, Pascal
• Department of Computer Science, FEIT,
• and ANU Supercomputer Facility,
• Australian National University
• http//wedge.anu.edu.au/

2
Limits of Vision of a human eye

• Total 15M pixels over the FOV of 4/3? (4)
  steradians, most dense in fovea.
• Pixel resolution
• 28 seconds of arc - highest resolution
• 50 seconds of arc - "20/20" vision
• 1.5 arc - minutes - "20/30" acceptable vision
• Normal 18" desktop computer at 24" and 1280 x
  1024 resolution is at limit of resolution.
• Small 48 cm. TV at 3 metres and 200 lines
  resolution can be improved by about a factor of
  two (eg. SVHS or Digital).
• Each screen has resolution 1280 x 1024, image
  area 1.5 x 1.25 metres and viewed from about 1.5
  metres yields a FOV of 0.8 steradians per screen.
• Stand in 4th corner of WEDGE and the corners make
  90 degrees, ie. about that of stereo vision,
  yielding a FOV of ?/2 ie. about 1.6 steradians.
  The display limit is about 20 of the eye limit.

3
Depth Clues from real world

• 1. Occlusion
• 2. Perspective projection
• 3. Binocular disparity
• 4. Motion Parallax
• 5. Convergence
• 6. Accommodation
• 7. Atmospheric
• 8. Lighting and Shadow
• Workstation 1, 2, 7, 8 "VR" adds
  3, 4 and 5

4
Virtual Reality (virtual environments)

• 3D (perspective) computer graphics in stereo
• Interactivity
• Mouse
• 6D Mouse
• Head tracking
• Robotic arms......
• Human Computer Interface research (HCI)
• High end Silicon Graphics supercomputing
• Games end PC cards helmets fun parlours

5
The first Wedge
6
The big wigs get their day
7
Rod receives the WORD from Henry
8
Wedgeorama
9
The p-Wedge at Wagga-Wagga (outreach)
10
Immersive projection-based VR

• Headsets are cumbersome and daggy?
• complaints of motion sickness
• solitary enjoyment?
• The CAVETM
• Small room with back (and down) projected
  stereo images
• Immersive viewers are surrounded by the images
• Collaborative
• 6D mouse head-tracking maybe audio...
• Fraternal user group interaction
• Expensive

11
Barriers to the diffusion of VR technology

• Expensive
• Applications not fully developed
• HCI Visual overload can cause discomfort
• The Wedge
• Built from the bottom up (including software)
• Sacrifice interactivity for affordability
• Driven by a particular application
• Driven by a particular idea
• First immersive VR theatre in Australia

12
The Wedge is...

• Two screens (standard rearlight) back-projected
  in stereo
• Frame made of extruded aluminium flush with the
  floor
• Two CRT projectors
• NEC Multisync XG75
• 800 x 600 non-interlaced images at 120 Hz (60Hz
  each eye)
• Intergraph TDZ2000
• Shutter glasses and emitters
• Ultrasonic head-tracker with 6D mouse (Logitech)

13
Intergraph TDZ2000

• Dual 300 MHz Pentium II
• 128 MB RAM
• 64 MB texture memory
• 32 MB frame buffer
• two VX25 graphics boards with frame
  synchronisation at 120 Hz (two raster
  accelerators and one geometry accelerator)
• resolution up to 1824x1386 pixels
• 1.6 M Gourad shaded triangles per second

14
Head-tracker

• Logitech (Fakespace)
• 23 kHz
• Three loudspeakers and three microphones mounted
  in plastic equilateral triangles (of length 25 cm
  and 5cm respectively)
• Range over 1.5m cone shaped volume angle of 100
  degrees
• Resolution of 100 micrometers in position and 0.1
  degrees in orientation
• Tracking speed up to 75cm/s rate of 50Hz
• Also 6D mouse

15
Driving idea...

• The corner region of the Wedge appears to offer a
  greater sense of presence than a single screen
• Depth cue associated with the recession of the
  screens into the distance
• Anecdotal evidence based on the experience of
  thousands of observers (Wedgeophiles)
• Images in front of screen more compelling than
  images behind the screen

16
Driving Application

• Plasma Fusion experiment at ANU the H-1 Heliac
  national facility
• Interactive engineering in a complicated and
  crowded geometry
• Understanding and communication of physics
  results
• Remote stereo video with lip synch audio for
  teaching and the virtual university

17
Preliminary applications and performance

• Simple molecules (C60 - bucky-ball) with
  vibrational motion
• Mathematical minimum energy surfaces points,
  wireframe and solid
• Percolation simulations
• Presently limited to 10-20,000 polygons _at_ 10
  Hertz increased this by a factor of 4 in 1999
  and with the new Wedge in ANU Comp Sci a factor
  of 10 or more.

18
Image Quality

• Resolution, matching, synchronisation all good
• Ghosting occasionally distracting
• Light extinction efficiency and spectral bias of
  the shutter glasses
• Decay time of the phosphor tubes in projectors
• Perception of ghosts also depends on
• Horizontal scan rate
• Colour palette
• Movement (animation)
• Suggestion
• Ghosts are usually tinged green

19
Shutter Glasses

• Synchronised to left/right eye images by infrared
  signals
• Use crossed polarising filters finite extinction
  efficiency
• We have examined two types of shutter glasses
• industry standard (about US600 a pair)
• home entertainment (about US30)
• needed to be modified electronically
• both have about 20 extinction!
• closed shutter glasses have a bias towards green

20
(No Transcript)
21
Projectors

• Measurements of phosphor decay times were carried
  out using a photodiode and oscilloscope
• Green (3ms half width) is about 1.5 times longer
  than red (2ms)
• Blue is very fast
• Phase varies through the image (due to finite
  horizontal scan rate
• Problems getting CRT projectors as DLPs
  (Victorian Branch) are taking over

22
(No Transcript)
23
Conclusions

• Wedge is a simple and effective VR system
• Very popular with the general public
• Simple JAVA 3D operating system
• More application developments coming
• Total equipment cost about US60k
• Ideal for remote teaching

24
Virtual Language

• The field is deeply rooted
• in cross disciplinary research.
• We intend to thrust
• into this virgin soil
• and break down conceptual barriers
• to plant the seed of new ideas.

25
WEDGE Language

• The Wedge was conceived to envelop the user
• who is drawn into the virtual environment
• which gives birth to new concepts
• and nurtures the growth of new ideas.