Visualization Wall Software

Contents:

Disclaimer

The software on this page is not warranted to have any practical use whatsoever. It is not pretty, it is not fully de-bugged, and it is not the best solution available. It is considered "good enough" around here - at least until some annoyance crops up and it gets re-written, by-passed, or tossed. Use at your own risk.

General Software

The master, visualization, and compute nodes run Red Hat Enterprise Linux 4 with updates. A few of the important package versions for working with the Viz Wall are:

The image viewing program "xv" is not free, so Red Hat does not include it in its distribution. The program is quite useful, and version 3.10a is used in the image display scripts below.

Although the ImageMagick tools can do all sorts of image manipulations, libtiff contains some excellent TIFF image manipulation tools. Pixar has their own versions of these tools that are distributed with their PhotoRealistic Renderman software, and have a few extra options I like. For manipulating TIFF images, these tools can run many times faster for large images than using ImageMagick commands.

Cluster and Monitor Control

The nodes of the cluster are connected on a private cluster network, and use rsh and rsync for password-less communication and file transfer. This practice is generally abhorred by security experts and one would never do this over an open network, but is relatively common for clusters. For clusters with other communication standards, adjust accordingly.

A note about node numbering. The nodes of are numbered using three digits. The head node is wall000, while the visualization nodes are wall001 - wall016.

In order to access the X server on each node, one has to have the proper authorization. When Red Hat boots to a graphical login prompt, it is running gdm. The X authorization file for gdm can be found in /var/gdm/:0.Xauth on each machine. One needs to extract this authorization and add it to the wall user's Xauthority file. Assuming home directories from the master are NFS mounted on the nodes, the following perl script can be adapted and run by root on the master.

Once you have X authority, you can control the screens remotely. Turning the screens on and off uses the "xset" command to control the dpms features. The following perl script can be used to turn all the screens on and off.

One annoyance is that the screensaver may be set, and the displays will start to go black in the middle of a demo. The perl script below again uses xset to turn off the screensaver. There are vague recollections that if dpms is in the wrong state, the screensaver doesn't get turned off. If one uses "wall_monitors.pl off", "wall_monitors.pl on" first, then the screensaver most definitely gets turned off.

Another annoyance is that the mouse cursor can float atop the graphics one is showing. A simplistic solution is to use the program "x2x" to one monitor and shadow the rest of the wall monitors. One then controls the mouse on all the displays and can drag it to a corner. For some silly reason, demo viewers seem to think its cool to control 16 mouse cursors at once. For this and other stupid x2x tricks, an alias to a command something like the following is useful.

Image Display

TO DO: Add some details of how I use the above codes.

Movie Display

NPB / Chromium config files

TO DO: Add some details of how I use the above codes.

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Page last updated on: June 4, 2004