Visualization Wall Hardware

Contents:

Pictures


Frank Summers and his visualization of large scale structure in the universe on the Viz Wall. (140 kb JPEG)
The cluster of visualization nodes is conveniently located in a computer room adjacent to the room housing the master workstation and the display. (44 kb JPEG)

The back side of the visualization nodes. The beige cables are 5 meter DVI cables that go under the raised floor and up to the monitors. One can see the monitor mountings and the 16 monitor boxes through the windows. (60 kb JPEG)
A closer look at those 16 monitor boxes. (56 kb JPEG)

The master workstation and the Viz Wall display shortly after initial assembly. The monitors had not yet been adjusted to be flush with one another. (56 kb JPEG)
The viz wall display with the monitors opened up to show the mounting structure. (48 kb JPEG)

Computers

The computers that drive the Viz Wall are just a standard cluster of Linux computers, commonly referred to as a beowulf cluster. The master and visualization nodes were purchased from PSSC Labs in spring 2002. The RAIDZone NAS was added in fall 2002, and the compute nodes were added in spring 2003. Five Opteron computers were added in 2004-2005, another 3 TB NAS in 2005, and a new master node and a backup master node were added in 2006 (all from PSSC).

To make beowulf nodes useful for a visualization wall, one simply adds a reasonably good graphics card to a standard compute node. At the time, that meant using an AGP riser card in a 2U rackmount box (since a gigabit ethernet card was needed as well). It would have helped to have fast disks to serve files quickly, but we did not have the money at the time, and got reasonable performance with standard 7200 RPM IDE disks.

Master Node and Backup Master Node:

Visualization Nodes (14):

Compute Nodes (12):

Opteron Nodes (5):

Other:

Display

The display is simply a 4 x 4 array of flat panel monitors.

This set-up has the major disadvantage of having seams between the panels, but it was chosen for several reasons:

  1. easiest to implement by a one-person team
  2. requires much less space than a projector set-up
  3. generates much less heat than a projector set-up
  4. considerably cheaper than a projector set-up
  5. requires much less engineering/maintenance for alignment, color balance, etc. than a projector set-up
The monitors chosen were a balance of largest size, fastest response time, highest contrast, best color, and thinnest bezel. The Iiyama 4637 had the thinnest bezel at the time, but had real problems with color response for faint colors. The transition to black was not smooth: an unacceptable problem when showing astronomy pictures. The Samsung 191T has compromises too. For example, one is extremely limited in setting the color response of the monitors, although, fortunately, that has not been a large problem.

The Ergotron display mounting was pieced together from their standard parts. It cost more than building a mount (as others have done for their flat panel display walls), but it did not require any machine shop expertise and could be built by a lone astronomer.

The DVI cables are noted below because they had to stretch from one room under the raised flooring to the adjacent room, and up to the monitors. The inexpensive cables did not carry the signal over that distance. A video tech here at STScI suggested Inline, and their cables worked great.

Display Hardware:

Main Viz Wall_Page My Home Page

Page last updated on: March 23, 2007