CS 4470 6456 Principles of UI Software

1
CS 4470 / 6456Principles of UI Software

• Large Interactive Surfaces

2
What do we mean by Large?

• Foot Scale Devices
• 21 CRT - 500
• 21 LCD - 2600

3
Meter scale devices

• 42 plasma Screen - 2400
• 65 Projection TV - 2300

4
Getting Bigger

• Projection - 1500 - 50,000 (per unit)
• Variable display size (optical throw lumens)
• Tiled Displays
• Rear Projection vs. Front Projection

5
Ridiculous Sized!

• Toronto Canada Skydome Jumbotron 33 x 110 feet
• 17 million
• 1985 International Science and Technology Expo
  40 x 25 meters

6
Resolution

• Jumbotron 1-5dpi
• Monitors 72dpi
• Humans can see dots/pixels 150 dpi
• Laser Printers 300-600 dpi
• 5color/magazine/glossy 2500 dpi

7
Some Research Work

• Stanford Interactive Mural
• Princeton Display Wall
• UNC Chapel Hill Projection Technology Ramesh
  Raskar

8
Stanford Interactive Mural
Rear Projection 6 by 3mural. 4x2 Array of XGA
(1024x768) projectors at 900 lumens. 3796 x 1436
or 50-60 dpi
9
Alignment Overlap Issues

• Projector overlap areas
• Color temperature differences
• Overall brightness (additive property of light)
• Between projector brightness differences

10
Stanford Interactive Mural

• Alignment
• Unspecified possibly physically aligned
• Overlap
• Software compensation, alpha blended polygons.
• Video

11
References

• Humphreys, Greg and Pat Hanrahan. "A Distributed
  Graphics System for Large Tiled Displays" to be
  published in Proceedings of IEEE Visualization
  99, San Fransisco, CA, October 24-29, 1999.
• For more rear projected display walls, see
• http//www.ncsa.uiuc.edu/TechFocus/Deployment/DBox
  /documentation.html

12
Princeton Display Wall
http//www.cs.princeton.edu/omnimedia/
24 projectors 6x4 array 8x18 size 6000x3000
pixels 30 dpi
13
Original 4x2 array (1998)
14
Projector Array (4x6 2000)
Note Physical Masks
15
Princeton Display Wall

• Alignment
• Work on automatic alignment in software using
  pan/tilt/zoom camera. (1/2 pixel error)
• Overlap
• Physical Masks

16
Office of the Future Project
http//www.cs.unc.edu/raskar/Office/
UNC Chapel Hill
17
Work by Ramesh Raskar

• Student at UNC Chapel Hill under Henry Fuchs
  Greg Welch
• Now working at MERL (Mitsubishi Electric Research
  Laboratory)
• Projector alignment overlap
• Ramesh Raskar, Greg Welch, Matt Cutts, Adam Lake,
  Lev Stesin and Henry Fuchs, The Office of the
  Future A Unified Approach to Image-Based
  Modeling and Spatially Immersive Displays," ACM
  SIGGRAPH 1998, Orlando FL

18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
My Work

• Implementing algorithms from
• Dynamic Shadow Elimination for Multi-Projector
  DisplaysR. Sukthankar, T.J. Cham, G. Sukthankar.
  Proceedings of CVPR 2001
• Shadow Elimination and Occluder Light Suppression
  for Multi-Projector DisplaysT.J. Cham, J. Rehg,
  G. Sukthankar, R. Sukthankar. CVPR Demo Summary,
  2001

25
Single Projector
26
Dual Projectors - Passive
27
Dual Projectors - Active
28
Occluder Light Suppression
29
Large Surface Input

• Through Screen IR
• Passive
• Active (Liveboard)
• Requires rear projection (area)
• Surface Sensing
• Contact Closure (SmartBoard)
• DiamondTouch / SmartSkin
• Rear Projection Difficulties

30
Large Surface Input (cont.)

• Camera Based Tracking/Recognition
• Pen Tracking
• Mimio
• Ebeam
• Issues of Scale
• Cost
• Calibration

31
Multi-Resolution Issues

• Input Output can be at different resolutions
• Output can have multiple areas at different
  resolutions (focus context) video

32
Surface Manager Issues

• Handle multiple output surfaces
• Map input and output
• Discovery coordination