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GeoWall 101

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 ?.

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GeoWall 101

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  1. GeoWall 101 Vaidya C. Atul Nayak

  2. Outline • What is a GeoWall ? • What are the components of a GeoWall? • How does it work? • Setting up the hardware. • GeoWall software.

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

  4. 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.

  5. GeoWalls in Use

  6. June ‘02 Sept. ‘02 70+ Walls since Jan 2001 70 • 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. Other 40 Geosciences

  7. GeoWall Components

  8. 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

  9. Projectors • Use InFocus LP 530 DLP projectors. • As compared to CRT projectors DLPs are: • Cheaper. • Brighter. InFocus LP530

  10. Screen • Front projection • StewartFilm 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.

  11. CircularPolarizers Left Eye Right Eye Passive Stereo Schematics

  12. 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.

  13. 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).

  14. 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.

  15. 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.

  16. 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.

  17. Projectors Mount • Front Projection • Easier to setup. • Cannot move too close to the screen as shadow causes loss of immersive experience.

  18. 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.

  19. 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

  20. 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

  21. Projector Alignment

  22. 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.

  23. 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.

  24. 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

  25. Application Software • ImmersaView • Requires • Windows/Linux • fltk (fast and light toolkit). • Open Inventor • http://www.coin3d.org

  26. 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

  27. 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.

  28. Stereo Images • Images can be taken in stereo using Stereo Cameras. • Viewed using Viewer or Wallview.

  29. 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.

  30. GeoWall Web page

  31. Cost of parts

  32. 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.

  33. GeoWall in Chile • GeoWall was part of the demos at the Internet2 conference in Chile. • Proof of “Pack and Go” stereo.

  34. Questions?

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