
Junkyard Jumbotron: join all your screens into one big one, no software needed - danshapiro
http://www.boingboing.net/2011/03/13/junkyard-jumbotron-j.html
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syaz1
Slightly OT, how do they do it on TV shops where they put a lot of TVs to form
a big screen? How are the images split? Can I do it with any TV?

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joshu
i think there are boxes that do it. the googleable you are looking for is
"video wall"

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ck2
quote:

 _RickBorovoy_

    
    
      To make your own Junkyard Jumbotron, please use  
      http://jumbotron.media.mit.edu
      The jj.brownbag link above is an earlier version of the software. 
      And please post your feedback / results on the Facebook page at    
      http://www.facebook.com/pages/Junkyard-Jumbotron/207846822564634

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philthy
This is similar to the digital billboard panels on the sidelines at sporting
events. There are some augmented reality applications possible with this idea
too.

Back in the seventies and eighties before very large TVs having 20 TVs daisy
chained together was all the rage to have in your coke dealer mansion.

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metageek
> _This is similar to the digital billboard panels on the sidelines at
> sporting events._

Yes, those are called Jumbotrons.

<https://secure.wikimedia.org/wikipedia/en/wiki/Jumbotron>

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philthy
No sir I am talking about the field level panels for advertising purposes:

[http://en.cnledw.com/upload/2010/08/30/201008301153735939.jp...](http://en.cnledw.com/upload/2010/08/30/201008301153735939.jpg)

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pedrocr
Couldn't get two screens on the same computer to calibrate properly. One of
them always showed up with the big broken sign. I had to use two different
browsers for it to even create two patterns so maybe there's a bug in the
calibration when the two screens are on the same computer.

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bodski
This could be really interesting for people working with digital art
installations (using old PCs and monitors/TVs).

A shame that its not likely to work with the wooden 'mirror' though:
<http://www.youtube.com/watch?v=HCSbk9JDwPY>

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joshu
combining cell-phone screens automatically? lame.

combining video projectors automatically? awesome.

i wonder if the code can deal with overlapping displays.

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Nate75Sanders
As apu points out, this is really well understood now -- has been for over 10
years, in fact. I think the fact that projectors are still fairly expensive
(though much cheaper than years ago) and most researchers aren't big
participants in the open source community is why we don't have anything
widespread.

At the University of Kentucky lab where I worked in 2002 (The Metaverse Lab),
we had a 24-projector geometrically/photometrically-corrected only-casually-
aligned system projecting on 2 walls and the floor with all 3 planes meeting
at a corner. Additionally, the system was cordlessly head-tracked (Intersense)
and the world view would dynamically change so that you could look around
objects, look under tables, etc. It was amazingly cool.

I'm pretty sure I could write the code for the geometric calibration of a 4-6
projector (whatever a single, stationary camera could see most of) single-
plane system in a day and then use the homographies (plane-to-plane mappings)
to warp and display large images geometrically seamlessly on the multi-
projector display. There would still be extremely apparent photometric seams
where the projectors overlap, though. You can use some simple models to get
rid of some of this, but REALLY making it look good in practice is hard, and
requires some engineering.

As with most things, making it look 80% good is easy. It's that last 20% that
requires years of engineering and a dedicated company like Mersive to make it
happen. Their stuff looks good.

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joshu
Oh, of course. It's just that sometimes making the 80% go from easy to trivial
is as interesting as the last 20% :)

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Nate75Sanders
For sure -- this is the essence of learning new fields without being a master.

I'm pretty certain if you buy 2 projectors, a camera (get a half-way decent
one, not just a cheap webcam), and read/study a few relevant papers, you'd
have a calibrated overlapping setup that you could send images to and show
reasonably correctly.

The great thing about this is that it's a lot like graphics programming --
once you get the taste of the positive feedback of small successes, you'll
want to start playing around with it a lot.

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josephcooney
No software needed _except a browser_ much less amazing than title suggests.

