[PD] many DVI ports with Debian/Ubuntu and Gem

cyrille henry ch at chnry.net
Mon Jun 7 10:00:34 CEST 2010

Le 07/06/2010 09:49, IOhannes m zmoelnig a écrit :
> On 2010-06-03 19:23, Hans-Christoph Steiner wrote:
>> I am looking into doing a 10 screen installation using Pd/Gem.  I'd like
>> to run it on as few computers as possible.  Anyone have any
>> recommendations for Debian or Ubuntu setups that can have like many DVI
>> ports in one computer?
> the biggest thing i did with something like this was an 8 projector
> installation [1], using a single computer (running ubuntu; i would have
> preferred debian, but some software we had to license was only available
> for ubuntu)) with 2 "recent" nVidia cards (forgot which ones; it was
> done last year, so probably it was 2 GTX295 or similar);
> 3 heads where equipped with triplehead2go, which would have made for a
> total of 9 projectors, but we only needed 8; the remaining head was the
> control computer to do the patching.
> there were 2 problems involved (and solved):
> - getting the gfx-card recognize the 3head2go over shitty cables (which
> we ended up solving by forcing EDIDs)
using good cable is also a good way to avoid problem...

> - window size:
> depending on your hardware/driver combination, you get a maximum texture
> size. with the cards we used this texture size was 8192x8192.
> this size (both horizontal and vertical) is an upper boundary for
> hardware-accelerated window sizes. so you cannot do a line of 8
> projectors in a row, each with a resolution of 1080p, as this would sum
> up to a window of (8*1920)x1080==15360x1920, and 15360 clearly being>8192.
> what you can do is to have your line of 8 screens form a virtual monitor
> of 4x2 screens, covered by a 7680x2160 window and use framebuffers for
> rendering the scene (this really only matters if there is continuation
> between the screens (e.g. in our project we actually had one huge 270°
> screen, which was fed by 8 projectors)
> if the screens are more or less independent, then it's way simpler)

i think the easiest would be to use 2 gem windows of 7680x1080, and render exactly the same scenne in both. just having to change the perspective of the openGL windows in order to have a perfect continuity...


> fgmasdr
> IOhannes
> [1]
> http://web.medienkunstlabor.at/projects/deskotheque/deskotheque-display-system.html
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