GeoWall

A GeoWall is a low cost interactive 3D stereoscopic projection system. It consists of a computer with a dual-output graphics card, two projectors, a rack to hold them, polarizing filters, silver screen, a pair of cheap polarized glasses for each user, and (optionally) one or two monitors. This can be put together for well under US$10,000, or bought as a turnkey system at a higher price from various vendors. There are equivalent systems under other names e.g. passive 3D display.
This article uses the word 'GeoWall' as a convenient trisyllabic equivalent for "low-cost polarization-based dual-projector interactive 3D stereoscopic system". Interactivity is a crucial aspect to GeoWalls, particularly for real-time data exploration. Without interactivity, a GeoWall is merely a system for viewing 3D films – a cheap 3D IMAX on a smaller screen.
GeoWalls are examples of passive Virtual Reality, in the sense that there is no head tracking. Instead of a complete immersive experience for one user, there is a partial immersive experience for multiple users. This makes it suitable for classrooms, group presentations, aCloud.
Origins of the name.
The first GeoWall was built in January 2001 by Prof. Jason Leigh at the Electronic Visualization Laboratory (EVL) at the University of Illinois at Chicago, home of the Cave Automatic Virtual Environment (CAVE), when asked by Paul Morin if a stripped-down single-wall CAVE would provide a level of 3D immersion acceptable for exploring geoscience data at a price affordable to smaller institutions like museums and academic departments. So instead of a complete CAVE, it was only a single wall, and being used primarily for geology, it was a "geology wall" or GeoWall.
Shortly after the first GeoWall was built, the GeoWall Consortium was created to support the development and distribution of software and data for the GeoWall users. Today, the GeoWall Consortium remains an active user group, whose members have made available free and/or open-source software, content, and documentation. Over 500 GeoWalls have been built since 2005 and the numbers continue to grow. The GeoWall Consortium can be accessed through its website geowall.org and mailing list.
Data Interactively Explored with GeoWalls.
GeoWalls have been used to explore data in several domains. Stereo photographs and movies can be viewed on a GeoWall, as well as most 3D models. Here are some examples of other data sets that are freely available. All can be modified to work on regular single-screen computers.
Nick Schwarz has a list of more GeoWall resources.
Graphics Cards for GeoWalls.
The following graphics cards have been reported as capable of supporting GeoWalls. Geowall.org says that "on the most general level the graphics card needs to have two monitor outputs to provide output to left and right projector".