Slashdot Mirror
New System to Counter Photo and Video Devices
Incongruity writes "News.com is reporting that a team from Georgia Tech has developed and demoed a system that actively searches for and effectively blinds cameras and camcorders within a 10 meter radius." From the article: "In this system, a device bathes the region in front of it with infrared light. When an intense retroreflection indicates the presence of a digital camera lens, the device then fires a localized beam of light directly at that point. Thus, the picture gets washed out."
A remote control will blind a camera in night shot mode, but it won't blind anybody. It can actually make a pretty cool looking lens flare, depending on the remote and the camera... I wouldn't be too worried.
Read the goddamn article:
How it works
The Georgia Tech system essentially exploits the "retroreflective" property of digital camera lenses. When light strikes a retroreflective surface, a portion of the light bounces back to the original source. While eyeglasses, bottles, watches and other glass surfaces are retroreflective, a coating on virtually all digital camera lenses puts cameras in a class of their own.
My blog. Good stuff (when I remember to update it). Read it.
And, of course, the eyes of some animals (cats, alligators) are strong and precise retroreflectors.
People, too.
That's why you get "red eye" in the picture if the flash is too close to the lens.
For people it's probably a vestigial remmanant.
For animals it's a night-vision adaptation. The retro-reflector is behind the light-sensitive part of the retina. Any light that makes it through the sensors is sent back (nearly) the way it came in, giving the retina a second chance to catch it and thus a tad under a 3db increase in sensitivity - at a slight cost to focus. The shine you see is what made two passes without being caught.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
A group of cameras are arranged in a ring formation, with their lenses facing inward. Typically, this ring is raised up about 10' or so above the ground, and the cameras aimed down toward a common area. Each camera's lens has a donut shaped ring mounted to it. The donut's surface is covered either red or ir emitting led. The light from these leds floods the capture area (the volume) and bounces off of reflective markers which are attached to the actors inside the volume. The cameras, which are IR sensitive pick up the markers, and a computer then uses the feeds from multiple cameras to triangulate the positions of the markers.
Anyhow, the Vicon guy did say that its not a good idea to stare into the strobes, as it was probably not healthy for the eyes. The red ones are probably less unhealthy, as your pupils contract due to the visible light. The ir ones don't emit any visible light, and the only way to tell if a strobe as working was by a green led stuck among the ir ones.
Just to wrap up this mishmash of info, and to make a point, I don't think flooding areas with ir light is a good idea, as I did find myself getting headaches and eyestrain if we left the strobes running too long in the studio.
My patience is infinite, my time is not.
I know I sugested that about a year ago here on slashdot. //yro.slashdot.org/comments.pl?sid=137379&threshol d=0&commentsort=0&tid=158&tid=126&tid=153&tid=173& tid=155&tid=137&mode=thread&cid=11485581
Part of "No Pictures, Thanks" from 1/26/05
It's actualy easier, you just need a high powered IR source, such as a bunch of LED's,
the Cameras AGC automaticly adjusts so you turn totaly dark.
I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso
In my (not so) humble opinion the law should treat tail-gaters as harshly as drunk drivers. There's no excuse for either and both are incredibly dangerous to other road users.
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