Electronic Visualization Laboratory (EVL) University of Illinois at Chicago GeoWall 101 Vaidya C. Atul Nayak

Electronic Visualization Laboratory (EVL) University of Illinois at Chicago

GeoWall 101

Vaidya C.

Atul Nayak


Outline

• What is a GeoWall ?

• What are the components of a GeoWall?

• How does it work?

• Setting up the hardware.

• GeoWall software.


GeoWall

• An inexpensive solution to view 3D data in stereo.


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.


GeoWalls in Use


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.


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


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


Projectors

• Use InFocus LP 530 DLP projectors.

• As compared to CRT projectors DLPs are:– Cheaper. – Brighter.

InFocus LP530


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.


Passive Stereo Schematics

Right Eye

Left Eye

Circular Polarizers


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.


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).


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.


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.


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.


Projectors Mount

• Front Projection

– Easier to setup.

– Cannot move too close to the screen as shadow causes loss of immersive experience.


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.


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


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


Projector Alignment


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.


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.


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


Application Software

• ImmersaView–Requires

• Windows/Linux

• fltk (fast and light toolkit).

• Open Inventor

• http://www.coin3d.org


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


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.


Stereo Images

• Images can be taken in stereo using Stereo Cameras.

• Viewed using Viewer or Wallview.


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.


GeoWall Web page


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


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.


GeoWall in Chile

• GeoWall was part of the demos at the Internet2 conference in Chile.

• Proof of “Pack and Go” stereo.


Questions?

Documents

Electronic Visualization Laboratory (EVL) University of Illinois at Chicago GeoWall 101 Vaidya C. Atul Nayak