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Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
GeoWall 101
Vaidya C.
Atul Nayak
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Outline
• What is a GeoWall ?
• What are the components of a GeoWall?
• How does it work?
• Setting up the hardware.
• GeoWall software.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
GeoWall
• An inexpensive solution to view 3D data in stereo.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
GeoWall or AGAVE or C-Wall ?
• AGAVE : Access Grid Augmented Virtual. Environment (predecessor to GeoWall).
• Geosciences community embraced AGAVE and named it GeoWall.
• C-Wall in addition uses a 3D tracking system.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
GeoWalls in Use
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
70+ Walls since Jan 2001
June ‘02 Sept. ‘02
40
70
Other
Geosciences
• Integrated into Univ. Michigan, Minnesota, Wisconsin, Indiana and Arizona State curriculum- ~3100 students per semester.
• Deployment at SciTech Museum in Aurora, Illinois; Museum of Science and Industry in Chicago.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
GeoWall Components
1. InFocus 530 Projectors 2 x $ 2550
2. PC with NVIDIA card $ 2500
3. Front Projection Screen $ 160
4. Projector Stand $ 420
5. Paper & Plastic Glasses $ 200
6. Polarizing Filters $ 70
7. Splitters, cables, etc. $200Total Cost $ 8650
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Recommended Computer Hardware Specs
• Pentium III 750 Mhz or higher.• At least 512 MB RAM.• Graphics card
– Should support Twinview – Recommended
• Quadro4 900 XGL• GeForce 4 Ti 4600
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Projectors
• Use InFocus LP 530 DLP projectors.
• As compared to CRT projectors DLPs are:– Cheaper. – Brighter.
InFocus LP530
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Screen
• Front projection– Stewart Film screen Corp– Coated with polarization preserving
material – DaLite silver.
• Rear Projection– Experimentation has led us to use ``Disney
black diffusion film'' (Dbd) for rear projection.
– Tip : Do not touch screen – coating goes off.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Passive Stereo Schematics
Right Eye
Left Eye
Circular Polarizers
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Passive Stereo
What is it?• Two projectors are used for the single
screen one for each eye's view.• Differently polarizing filters are placed in
front of each projector lens.• Users wear polarizing glasses where
each lens only admits the light from the corresponding projector.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Advantages of Passive Stereo
• Polarized stereo glasses cost much less than the LCD shutter glasses used in active stereo.
• Less fragile (you can stop worrying about collecting the glasses after the show is over).
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Polarizers
Two types of Polarizers• Linear • Circular • Circular preferred.• Place polarizers some
distance away from the bulb.• Holder– Use PCI
Slots+Velcro to stick on projectors.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Polarizers
• Circular– Works better because
light is circularly polarized.
– Effect is not dependent. on alignment of viewer’s glasses.
– Are more expensive.– Required if you plan to
use head tracking.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Stereo Glasses
• Glasses to see stereo• Linear or Circular , depends on
Polarizer used.• Disposable paper versions,
reusable plastic and aviatorstyle.
• Cost much less than the LCD shutters used in active stereo.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Projectors Mount
• Front Projection
– Easier to setup.
– Cannot move too close to the screen as shadow causes loss of immersive experience.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Projectors Mount
• Rear Projection– Better utilization of front space.– Ability to go closer to the screen without
shadows disrupting the immersive experience.
– Space required behind the screen.– Can use a mirror to bounce the light – to
reduce distance behind the screen.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Projectors Set up• In order for the passive stereo to
work, the images from the two separate projectors should match up on the screen.
• Projectors aligned when most of the left and right images (mostly in the central areas of the screen) overlap.
• Vertical disparity is more offensive than horizontal disparity.
A typical projector mount setup
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Projectors Set up• We use velcro to stick
polarizers in front of the projectors.
• Use this test pattern file to make sure the projectors are aligned
• http://www.evl.uic.edu/cavern/agave/GeowallAlignment.jpg
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Projector Alignment
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Projector Alignment
• Vertical Disparity difficult to view compared to Horizontal Disparity
• Projectors alignment cannot be perfect as cheap projectors and improper polarization.
• Geometric Alignment of the two images is being done.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
System Software
• Windows XP/2000.• Linux (tried with Red Hat 7.3 and up, and
Suse 7.2 and up).– www.redhat.com
• Any window manager for Red Hat.• Prefer fvwm window manager for Suse. • Get latest Drivers from NVIDIA site,
www.nvidia.com.• Linux use NVchooser.sh to get the Driver
version.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Application Software• ImmersaView
– Open Inventor model viewer for the GeoWall– The data can be a single Inventor model or a
flipbook of models
Screenshot of Immersaview
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Application Software
• ImmersaView–Requires
• Windows/Linux
• fltk (fast and light toolkit).
• Open Inventor
• http://www.coin3d.org
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Stereo Viewers• Wallview
– View Stereo images in Windows– Large images loaded fast– Can also use ‘Irfanview’
• Viewer– View Stereo images in Linux– Multifile support and Slideshow.
• Other Software– Vis5D– Walkabout
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Interaction in GeoWall
• Can be use keyboard, mouse,joystick.
• Tracking can also be performed in GeoWall.
• YG and other software that runs on the CAVE can also be used on the GeoWall.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Stereo Images
• Images can be taken in stereo using Stereo Cameras.
• Viewed using Viewer or Wallview.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Tips for a good demo
• Buy both the projectors at same time , they will then age together.
• Sound card “Sound Test live” is recommended if sound is required.
• Carry an Extra projector.
• Stay away from the screen.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
GeoWall Web page
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Cost of parts
1. InFocus 530 Projectors 2 x $ 2550
2. PC with NVIDIA card $ 2500
3. Front Projection Screen $ 160
4. Projector Stand $ 420
5. Paper & Plastic Glasses $ 200
6. Polarizing Filters $ 70
7. Splitters, cables, etc. $200Total Cost $ 8650
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
The Mac GeoWall
• Created by Andy Johnson at EVL.– Being used to teach sixth
graders scientific enquiry.
– Meant to replace more expensive immersadesk being used till now.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
GeoWall in Chile
• GeoWall was part of the demos at the Internet2 conference in Chile.
• Proof of “Pack and Go” stereo.
Electronic Visualization Laboratory (EVL) University of Illinois at Chicago
Questions?