solutions

I got a bunch of really helpful feedback, from my HELP! post and here it is, in case it is of use to anyone else:
From Cefn:

I've been using GEM with PD to lay realtime video across multiple monitors.

As described in the first few lines of this intro to building PD, http://cefn.com/curiosity/?page_id=147 a guy called Vade helpfully provided me with PD patches for video to multiple monitors, so I feel honour bound to helpfully pass them on to you.

http://lists.puredata.info/pipermail/pd-list/2006-01/034396.html is a direct link to the archived discussion with Vade on the PD list, but I don't think you can get the attachment from there, so I've reattached it here.

While in my case each monitor shows the same subsection of the video, I think it would just be as easy to take different parts of the frame. GEM is essentially rendering the whole video, and then taking a defined window on this which could have any coordinates I think. Depends what the source is which needs to be splurged across the monitors whether this approach would help, but PD will manage most sources.

Hope this helps. I'll know more in two weeks when I finish off this PD Bootcamp...
http://goto10.org/-/pdsummerschool2006

Cefn

another reply from Sean offered this help:

http://curiositycollective.org

think your two options are:
1: rear projection using a 2000+lumen projector
Depending on how the light hits, which is to say if sunlight doesn't fall directly on it (or if it's cloudy) you may get a decently viewable result. The smaller you project the brighter it will be. I have some rear projection screen material I could probably give you a piece of, which is 3 feet by however long (and you could probably join a few with scotch tape and it would look pretty good.
Turn the projector on it's side for portrait...

2. Multiple screens.

You aren't going to get less than about 1/2" gap (and that's with LCDs)...but you can be tricky and use the fake window pane divider moulding to make it look like it's supposed to be separate.
2 big plasmas with door frames could work too...but LCDs and plasmas are both quite expensive, and unless you take the LCDs out of their enclosures, you are going to have an even bigger gap.

CRTs will have at least a 2" gap, generally, between the active picture areas, and also can interfere if they are very close together.

Driving:

Driving the projector is simple.
Driving multiple monitors requires either multiple computers or 1 computer with many video outputs, or potentially several DVD players...
If you are doing stills the 1 computer multiple video output (there are both dual head video cards ($100 each or so) as well as the Matrox tripple-head video splitter ($200 I think) can work decently...

For video I've done a 3 screen setup with 3 separate DV files on 3 computers and synchronized them using 3 copies of arkaos, but I think there are much simpler ways to do it.

Hope that helps some-unfortunately what you are trying to do doesn't come cheap (unless you can find someone with a matrix-video wall divider to borrow)

let me know if there's anything else I can help with.

-sean

and from Paul:

What you'd like to do is both technologically difficult, and more
importantly, expensive. You can't just run a graphics card in every PCI
slot on a desktop PC. You need a way to distribute the information, so a
cluster of PCs and graphics cards is needed, along with a distribution
balancer/manager thingie, like MPI. Once you can do that, it's easy to
display images in either portrait or landscape view. I THINK that there
are virtual cluster packages available, so that you can run many monitors
from a single PC, with a corresponding major hit in speed. If you only
need to update every few seconds, that will probably work.

I'm by no means an expert...I'm a rock mechanics guy, but I'm part of the
EarthScope project funded by congress, and the visualization team is at
Scripps...here's a website referencing what I think you're looking for.
Scripps is SIO...

http://www.evl.uic.edu/cavern/glvf/gallery.html

You'll note that all of the montors have the bezels (front edges) on. If
you don't like that, and want a more integrated look, you can just remove
the bezels...they usually just pop off the front. You need to take care
when stacking the montors, as having the bezels off makes it easier for
them to fall apart (completely out of the housing).

Honestly, if you're interest in doing this is just to have enough
brightness so that people can see the image during the day, I would
recommend installing an awning on the outside of the building, and just
going with a projector. Or, maybe you could build a booth/tent/private
viewing area? And webcam the response of the person in the booth? I think
that you might be doing that anyway. My friend Mary Fuller sent me your
proposal...

Sorry that I couldn't be more help. I love Boston in the summer...it would
have been nice to have an excuse to fly over there.

best,
Paul