Tools and Applications for Large-Scale Display Walls

This article extensively describes the workings behind a rather grand endeavor undertaken by a group of professors, scientists, and researchers in the realm of computers. The purpose of this project named The Princeton Scalable Display Wall Project is to break the current bottleneck in computer display resolution power. This project was started in 1998 and set out to come up with a large-format, high resolution display built with inexpensive components. Their first attempt used an 18x8 foot rear projection screen and eight LCD projectors. It could pump out 4,096 x 1,536 pixels by way of 8 PCs. They scaled up their equipment in 2000 to 24 DLP projectors being driven by 24 Pentium III PCs pumping out a staggering 6,144 x 3,072 pixels. Such an elaborate system could be a nightmare to use for the leman so the authors had to develop tools to align, color balance, and manage tiled display systems. They also wanted to create the look and feel of a single display with accurate alignment and color balance. Manual alignment would be impractical for this setup so they developed an automatic alignment method that lets computers warp images to get pixel accuracy for the large projector display. Another issue the developers faced was color balance. Balancing a large projector array's color and luminance proved to be very challenging. Their solution was to use a color mapping algorithm that operates over many colors at one time as opposed to single color channels. One could imagine what a mess it would be to manage 24 computers, 24 projectors and all the software that's involved. To overcome this challenge the team came up with a tiled display management tool they named DwallGUI. This feature offers a wide range of functionality. One of its most interesting features is the ability to enable users to broadcast the keyboard and mouse commands and simultaneously see the results on the gigantic display. Another hurtle to overcome with a large-scale multiprocessor system such as this one is to get scalable performance while requiring minimal communication between computers. The authors solved this problem by coming up with an IMAX quality MPEG decoder. It uses a hierarchal parallel decoding system. This approach requires a much smaller network bandwidth requirement than previous systems. It does this by only transferring encoded macroblocks and reference material.

The range of applications for a technology such as this is very wide. One that the researchers