[PD] Pd/GEM and camera for tracking

[David Kirkpatrick]

Hi Jack,
 
Yep, your chain is right. A minor difference is that I use two BNC baluns (one with a BNC to composite adaptor attached), but it should make very little difference. I also used a UTP cat 6 cable instead of cat 5, but I used cat 5 baluns.
 
I've used this chain in multiple theatrical projects without noise issues, even with moving lights messing up the ambient light levels. Obviously you would have a dodgy signal if you ran the UTP cat 5 or 6 alongside a 3 phase lead or something, but apart from that you should be fine. I had the cat 6 lead running through a lighting grid full of 240V and it didn't degrade. It actually seemed cleaner than doing everything with coaxial cable.
 
David Kirkpatrick



CC: pd-list at iem.at
From: jack at rybn.org
Subject: Re: [PD] Pd/GEM and camera for tracking
Date: Sat, 7 Mar 2009 13:15:16 +0100
To: djk_1200 at hotmail.com

Hello David,


Thanx for all this informations using an analogue camera.
It's good to know there is FireWire extensions, but it is very expensive (245 pound sterling !).


If i understand, the system is like this :
Analogue camera with BNC -> BNC baluns with power -> cat 5 cable -> composite baluns with power -> composite to FireWire400 converter -> FireWire400 to FireWire800 cable -> MacMini -> Pd/GEM ?


I know that analogues cameras are good solutions, but with all this stuff, there is no risk of noise ? ;) (tell me if i'm wrong).
++`


Jack




Le 7 mars 09 à 06:18, David Kirkpatrick a écrit :



Hi Jack,
 
I've done a fair bit of this sort of thing before. The most useful setup i've found is:
 
1) Analogue monochrome CCTV camera. (Preferably with around 700 horizontal lines or so, very low lux, and self syncing)
I use these. http://www.allthings.com.au/Catalogue/CCS/monochrome%20low%20light%20cctv%20dsp%20video%20camera.html
You can then buy a C or CS lens that is the right angle for your situation. For roof mounted stuff I use an ultra-wide angle varifocal set to just before it noticably fisheyes.
 
2) Cat 5 balun connected to CCTV camera's analogue video output and power input. This allows signal to be sent, and power to be recieved via a single cheap UTP Cat 5 lead (i've gone 30 metres with no noticable image quality loss, supposedly you can go much further). Removes the need to run a mains power lead or coax lead to the camera so setup is quick and easy, and reduces time spent dangling from ladders. You can get sets of cat 5 baluns really cheap on ebay.
 
3) Second cat 5 balun, on the other end of the cat 5 lead, placed next to computer. Connect to a suitable power supply for your video camera, and connect signal to a near zero latency industrial firewire capture device such as a DFG/1394-1e. http://www.theimagingsource.com/en_US/products/converters/dfg13941e/ This allows you to hook up to a to a desktop or laptop, including a mac mini.
 
Then you're done. Just set Pd to listen to the DFG/1394-1e. Image will be clean and roughly equivalent to 720x576 res.
 
This setup can also be modified to work with near infra-red light instead of visible light if you want to avoid detecting lighting changes as movement. Just tape three squares of primary red and congo blue gel in front of the camera lens. Set up a few PAR56s to flood the space with light. Add the same gel to the 56's as you did to the camera and it will block almost all visible light. People will glow bright white when viewed through the camera, but most other stuff in the space will be close to invisible.
 
 
Alternately, if you want to use a firewire board camera, you can get something like a Lindy CAT5 FireWire Extender. They aren't cheap but they extend the maximum length of a firewire run from around 5m to 70m without quality loss.
 
 
Regards,

David Kirkpatrick





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