INTRODUCTION
Cameras are
ubiquitous today, and, from a technology perspective, the revolution is
just beginning. Video cameras are becoming smaller and cheaper while the
Internet is enabling unlimited live webcasting. Web camera usage has grown
from one in 1991
to hundreds in the mid-1990s to hundreds of thousands today. Video cameras
the size of postage stamps
can be procured for under $100, and will certainly become even smaller and
cheaper.
To many, this is good news. Public webcams enable remote
users to see what they would otherwise need to visit, and empower local
subjects to have a voice and a face to the outside world. Private webcams
empower friends and family to see each other remotely, and to check up on
the safety of their homes and their loved ones.
But there is a dark
side. While hidden cameras are clearly an invasion of privacy, visible
public cameras can be as well. A camera placed in a legally valid site can
peer into otherwise private spaces. Their connections to the Internet
enable arbitrary numbers of users to watch anonymously. And telephoto
lenses enable cameras far greater vision than that of the human eye.
Imagine looking out your window and seeing someone on top of a building
with a large telescope looking down at you. Now imagine the nightmarish
vision of seeing thousands of people on top of the building with
telescopes looking down at you. Laws and conventions acceptable for a
single live gaze do not scale for remote multiple ones.
Live
image from robotic webcam near Paris aimed by anonymous web
user
On a personal note, I'm a camera-guy. For over
twenty years I've worked as an artist and researcher exploring new ways to
represent place, work which often involved custom-designed cameras for 3D,
immersion, and interactivity. Last fall I moved to a small town in Japan
for an artist residency, ostensibly to continue my work with VR and
webcams. But the dark times caught up with me and I felt compelled to ask
some deeper questions, like, when cameras are everywhere, is it possible
to become invisible from them?
The more I learned, the more I
realized the answer is, well, yes and no. I began by aiming an inexpensive
laser pointer directly into the lens of a video camera. The results were
striking. The tiny beam neutralized regions of the camera sensor far
larger than the actual size of the beam. Properly aimed, it could block a
far-away camera from seeing anything inside of a large window.
Then I looked around the Web. Relevant articles existed but were
highly scattered. Not surprisingly, a lot of data exists in the military
literature (much of which appears to be getting "re-classified" and
disappearing from the Web day by day). I realized that I could more or
less cover everything there is to know about camera zapping during my
residency, both in terms of practical information and of larger
metaphors.
I have some artistic and ethical discomfort with this
work. It's divided my artist colleagues into those who see a new activist
tool and those who liken it to burning canvasses. Indeed, is an anti-tool
a tool? Then there's the question of releasing potentially useful
information to criminals and terrorists. Perhaps, but anyone who really
wanted to knock out a camera wouldn't waste their time with harmless,
temporary techniques.
My interest and motivation is to provide the
creative community with some stimulating and provoking stuff. These are
stimulating and provoking times. This is a report of my findings.
BASICS
Cameras
Camera
zapping is possible because cameras are not perfect machines. Two such
imperfections are blooming and lens flare. Blooming is the technical term
for when a portion of the camera's sensor is overloaded, resulting in
"leakage" to neighboring regions. For example, a candle in an otherwise
dark setting may cause blobs or "comet tails" around the flame. Many video
cameras today advertise "anti-blooming" capabilities, but it's ultimately
a matter of degree. Most can indeed handle a candle light without blooming
but almost certainly not direct sunlight.
The other relevant
imperfection is lens flare, caused by unwanted light bouncing around the
glass and metal inside the camera. Multi-coated optics and good design can
minimize lens flare but not completely eliminate it. For example, it is
virtually impossible to eliminate the multi-facet reflection of the lens'
diaphragm blades in today's cameras when they're aimed at the
sun.
Another imperfection common in digital cameras occurs in the
electronics downstream from the camera sensor. Often, when one small
portion of an image is unnaturally brighter than its immediate
surroundings, the electronics get confused. The result may be large
digital "blocky" artifacts in the image.
In addition to these
imperfections, cameras' strengths can also contribute to their weakness,
for example with long, or telephoto, lenses. These lenses act as
telescopes, allowing the camera to fill its frame with a magnified image.
Since the field of view is small, the amount of light needed by the sensor
is proportionally larger. Consequently, telephoto lenses are typically
large, making concealment more difficult and detection easier.
Further, telephoto lenses exhibit a strong retro-reflective
effect, the bright reflection caused when viewing such things more or less
on-axis with a light source. Examples include animal eyes viewed with a
flashlight (held close to the observer's eyes), "red eye" in flash
photography, and the reflection of car headlights from retro-reflective
material common on today's running shoes. When a telephoto lens is aimed
at you, you will see a "glint" in the lens if you are shining a light in
its direction.
Lasers
Lasers
are near-perfect monochromatic light sources, in that they emit a single
narrow wavelength, one pure color (actually some lasers emit several pure
colors). The first lasers were made of glass tubes with polished mirror
ends and had the additional feature of emitting collimated light, a
parallel beam so precise that it could be extremely narrow (and therefore
concentrated) or could converge to a microscopic point.
It is
important to understand that a parallel beam of collimated light does not
lose any of its brightness travelling through empty space. Here on earth,
the atmosphere has enough density to diffuse and weaken a collimated beam.
But on a clear day or at night, a small bright spot from a well-collimated
laser will remain a small bright spot for distances of hundreds of
meters.
The solid-state revolution that replaced vacuum tubes with
silicon chips had a similar effect on lasers. Solid-state technology
allowed lasers to become smaller, more efficient, and much cheaper. Useful
new industries emerged, such as laser printers and laser-scanning at
supermarket checkout counters. Useless ones appeared as well, such as
cheap home laser light shows and laser pointers.
Laser pointer like this can be
found for $1 on the Web
Laser pointers represent a case
study of what happens when technological advancement and high volume
production reduce costs so much that a product simply happens, regardless
of need or utility. Laser and other light-based pointing devices were
originally made to help a lecturer highlight something on an accompanying
projection screen. So in theory, there need not be more pointers in the
world than lecterns or projection screens (or lecturers). But because
laser pointers could be made and sold for a few dollars, they found a
market as a novelty item. Red laser pointers can be bought on the Web
today for $1 or $2 each, while green ones are much more expensive
($200-$400) and blue ones are still in commercial
development.
Today lasers come in extremely wide varieties of type,
wavelength, and power. (Everything one would ever want to know about
lasers can be found on the Web at Sam's Laser FAQ.)
They range from lasers capable of
destroying missiles to tiny
lasers that create images directly on the human
retina.
Laser
Safety
Though lasers are often associated with danger
(think Goldfinger), their hazard level is related to power, wavelength,
and concentration, but primarily to power. Lasers are classified into four
classes (two of which have sub-classes). These range from "Class I" lasers
which are deemed never harmful (e.g., laser printers), to "Class IV"
lasers that can blind, burn, and sometimes cut through steel. The big
dividing line lies between Class IIIa and Class IIIb lasers, with the
major criteria being whether or not the laser emits more or less than 5
milliwatts. Class IIIb and Class IV lasers must be registered in many
countries, though a casual Web search suggests it's pretty easy to buy
serious Class IV lasers if one desires.
All off-the-shelf laser
pointers are Class IIIa lasers, emitting light from 1 - 5 milliwatts. The
official view is that they cannot burn or damage skin, but can produce
"spot blindness" under the right conditions and should have a "danger"
label attached. Spot, or temporary, blindness can indeed be hazardous, for
example, while driving a vehicle. But, contrary to the popular belief, not
a single instance of permanent eye damage from laser pointers has been
recorded anywhere, according to a report published in the Industrial
Safety and Hygiene News in May 2000.
In addition to spot blindness,
laser pointers can get people into other kinds of trouble. Today, many
sports arenas and concert halls ban laser pointers. Various direct and
indirect laws can be used to cite irresponsible use of laser pointers as a
misdemeanor. And since the beam from a laser pointer looks the same as the
beam from a laser-sighted firearm, you don't want to aim your laser
pointer at someone carrying a weapon. In June 2000, LAPD booked an
unarmed juvenile, who aimed a laser pointer at an officer's torso, for
"602 WIC 417.26 (c) P.C., (Laser Scope Pointed at a Police
Officer)."
HISTORY
Art and
Activism
Using bright light as an aggressive tool goes
back to ancient Greek mathematician Archimedes and the legend that he
burned invading Roman ships with large mirrors and reflected sunlight. The
activist art group, Rtmark (pronounced
"arteemark"), inspired by the Archimedes legend, distributed 1,000
hand-held mirrors to
protesters at the 2001 G8 summit in Genoa, to use against the police by
spot blinding them with sunlight.
The proliferation of surveillance
cameras has increasingly become a topic of concern in the arts and
activist communities. Rtmark has a Web guide to closed circuit television
destruction. (Though the guide includes laser pointers as a method, it
is not recommended, in part because it doesn't leave any visible sign of
inoperability. They prefer plastic bags, paint guns, axes, and rocks to
make their point.)
Community-made maps showing the locations of
surveillance cameras in public spaces are appearing on the Web. For
example, the NYC Surveillance
Camera Project has mapped over 2,000 surveillance cameras in Manhattan
through a network of volunteers. The artist/activist group Institute for Applied Autonomy
created a web-based application allowing New Yorkers to find walking routes to
avoid surveillance cameras.
Other forms of artist activism
against surveillance cameras are more light-hearted. The Surveillance Camera
Players, a New York based group, perform unannounced street theater
"for the entertainment, amusement and moral edification of the surveilling
members of the law enforcement community." The SCP organized a protest
against surveillance held on September 7, 2001, with 22 participating
organizations in 6 countries. Currently the SCP has several satellite
groups, including in Italy, Sweden, and Lithuania.
Anti-Surveillance
Products
Detecting and stopping cameras turns out to be
fundamentally difficult. Cameras don't emit anything (e.g., the way
cellular phones do). With a great deal of surveillance and
anti-surveillance products on the Web, virtually none could be found to
simply detect and stop cameras. (Cameras connected to transmitters,
perhaps, but cameras alone, no.) [October 2002 update: see Laser Dissuader
below.]
A Google search of "anti
paparazzi device" yielded two hits, both about near-identical devices
called "Eagle Eye" and "Backflash" (and both unfindable as actual
products). These devices apparently couple a light sensor to a flash unit:
when a flash of light is detected, the devices instantaneously flash back.
They're both small, made to be worn, and claim to obscure a portion of the
photographic image near them whenever a flash is used (ostensibly as
protection against intruding photographers). If these devices work, they
obviously would only work for still, flash
photography.
Military
The
gold vein of camera zapping material can (or could) be found in the
military literature. Indeed, the race to build the first laser (built in
1960) was fueled by DARPA funding. During the Cold War, both the Pentagon
and the Kremlin spent billions of dollars developing high-power laser
weapons, which continued during Reagan's "Star Wars" initiative in the
1980s and continues today. But as the silicon revolution made lasers
smaller and more efficient, the international military community looked
into additional opportunities. Two such opportunities were "antisensor"
and "antipersonnel" weapons.
Antisensor lasers are capable of
scanning a region looking for "glints" of reflected light coming from
lenses aimed at them, then switching to a high energy laser capable of
overloading or destroying the sensor (or whatever) behind the lens. The
U.S. developed such a system called the Stingray
and deployed two tank-based prototypes in Saudi Arabia during the Gulf War
(they allegedly were not used). The Stingray's range of operation is
claimed to be several kilometers. It's not clear if (or how) the Stingray
could discriminate between lenses and eyeballs, or between sensors behind
a lens and human eyeballs behind a lens.
Antipersonnel lasers are
made to "dazzle" (the technical term for spot-blindness plus its effects,
such as disorientation and delay). One such system developed by the U.S.
Air Force is the Saber 203. It's
designed to fit in the grenade launcher of an M-16 rifle and emits a beam
in-line with the rifle's scope, with an effective range of 300 meters. Its
28 milliwatt laser is considerably more powerful than the 5 mw laser
pointers, but it is claimed to be below the threshold of eye
damage.
The line between antisensor and antipersonnel lasers is
vague, since there is nothing preventing a soldier from using a Stingray
to permanently blind soldiers in the battlefield. The Human Rights Watch and
the
International Committee of the Red Cross led a campaign for a United
Nations ban on blinding laser weapons, which was adopted in 1996. Some
believe this only drove such development further into secrecy. Rumors
persist that Israel
acquired U.S. Stingrays after the ban, and that China has been making a
cheap version of the Stingray called the ZM-87 that can blind soldiers 2
miles away and disable soldiers 7 miles away.
At the same time, at
least two companies are marketing commercial versions of the laser dazzler
developed for the U.S. Military. The "Laser
Dissuader" and the "Laser
Dazzler" both claim to be safe, and better alternatives than bullets.
[October 2002 update: The Laser Dissuader link has changed since last
summer to include "SpyFinder," a new product that appears to detect
cameras by aiming a small laser and detecting the retro-reflection from
the lens.]
It remains uncertain whether any 100% successful
antisensor detecting system actually exists.
FIELD TESTS AND
PROTOTYPES
First field tests were conducted simply with an
inexpensive laser pointer aimed into the lens of a video camera. At close
range (1 - 5 meters), the beam was easy to aim by hand. The laser beam
almost completely obliterated the image, covering it with a red
starburst.The effect completely disappeared when the laser was aimed away,
leaving no trace of any permanent damage.
Inexpensive laser
pointer (1 mw, 650
nm red)
Laser
pointer aimed at video camera from 3 meters away.
This
cheap laser pointer emitted an oval-shaped beam (as is often the case)
that was about 2mm by 4mm in diameter at very short distances, and
expanded to over 5cm by 10cm at 100 meters (due to cheap collimating
optics). In medium and bright light, it was difficult to see with an
unaided eye. The obvious solution was to couple the laser to an optical
scope and pre-calibrate them.
Telescopes and binoculars generally
do not have cross-hair reticules built in, but rifle scopes do. Rifle
scopes are available at prices upwards of $2,000, but like handguns, most
of the market appears targeted at lower-income customers, and cheap rifle
scopes can be found for under $10. All rifle scopes have built-in
reticules with some form of cross-hair or dot at the center, which are
internally adjustable with set screws. The only problem is that, unlike
telescopes, rifle scopes are made to be viewed with the eye several
centimeters from the rear optics, since they are mounted in front of the
operator's face. (This distance is specified as "eye relief," and is
typically 2 - 5 inches but is never zero.)
A simple prototype
system was built with a $30 mail order 5mw red laser (635 nm wavelength,
which appears much brighter than 670 or 690 nm red) and a $10 rifle scope
with a 4X magnification (Tasco Rimfire, made for small game hunting). The
laser and scope were secured together and the cross-hair adjusted to
center on the laser beam at 100 meters.
Simple laser / rifle scope
system
Telephoto view from 100 meters,
cloudy day (video)
Wide angle view from 100 meters
(video)
Through
the rifle scope, the glint reflected from the lens was indeed apparent,
particularly when the camera lens was zoomed in. It was easy to
intermittently hit the lens but difficult to maintain aim by
hand.
A second prototype expanded in several directions. First, it
is tripod-based, with a precision head allowing independent adjustment of
its 3 axes (Bogen/Manfrotto "Junior Geared Head," complete system costs
around $200). Then, a larger rifle scope was used for a bigger, brighter
image (Tasco World Class 3-9x zoom, $70). Finally, the cheap laser pointer
was replaced with a laser gun sight, which has the same Class IIIa power
rating but much better optics, resulting in a more circular and collimated
beam (Beamshot 1001 for $110). These gun sights also have adjustment
screws to align the beam, durable metal cases, and many options of
mounting hardware. So, for under $400, a rather serious camera zapper can
be assembled.
Laser gun
sight, zoom rifle scope, 3-axis adjustable tripod head
Camera Zapper in window
approx. 200 meters from camera, early evening (video)
Telephoto view (video)
The system was portable and
could be quickly deployed. Aiming was extremely critical, and at long
distances, very careful fine tuning was necessary. But when the camera was
aimed in the direction of the zapper and zoomed in, the glint reflected
from the lens was very obvious. This system can work well for cameras
which are visible and stationary.
If either
the camera, or target, is moving, then some form of aiming and dynamic
tracking is required. One solution is to do it ourselves. A third
prototype was built to be small and hand-held for near and medium range
moving cameras.
Hand-held unit with laser gun
sight and golf scope
The result was made with a Beamshot
1001 laser gun sight and a small monocular made for golf range finding
(Tasco Golf Scope, $20), basically a small telescope with a grid-like
reticule inside. Unlike a rifle scope, its eye relief distance is zero,
which makes it comfortable to use hand-held. This new system could fit in
a pocket and was very easy to use. It turns out that precise calibration
was not necessary, since the beam is easily visible in the scope at near
and medium range distances. If one wanted to scare away a news
cameraperson, this system would be ideal.
LIMITATIONS AND
APPLICATIONS
It would indeed be a achievement to be
able to wear a small device that prevents your image from ever being seen
by a camera. (I once recklessly predicted such
a device myself.) And though it may be possible, it would not be without
limitations.
One limitation of using lasers to zap cameras is due
to their purity of color, which makes it possible to filter out. Filtering
can be done either optically (e.g., using a special green filter to filter
a red laser) or electronically, downstream from the camera sensors.
Neither are perfect solutions, and at best, filtering may provide a
recognizable image but without full color.
Original image, zapped, and
filtered (and readjusted by hand) to show green channel only
Filtering can also be counter-measured. The best method is to
use 3 lasers (e.g., red, green, and blue). The next best method is to use
a green laser, since most of the signal coming from a color camera sensor
is from the green element, the color to which our eyes are most sensitive.
The military solution is to use "wavelength-agile" lasers that can
randomly change color, rendering any filtering useless.
Another
limitation is how to track a moving camera automatically. In the long
term, this is (arguably) solvable using computer vision techniques. The
problem is more solvable if a human operator first constrains the range
and an automated system does the fine tuning.
The biggest
limitation - and this is where things ultimately get depressing - is
detection. Look out any window and ponder that cameras can be the size of
buttons. Cameras don't even need lenses; they can use "pinholes." It's my
conclusion that the problem of detecting cameras is ultimately unsolvable:
if someone wants to hide a camera, they can hide a camera.
There is
good news. Long, telephoto lenses, whose powers are greater than human
vision and therefore of special concern, are detectable. At least for the
foreseeable future, cameras that see far away can also be
seen.
So
in the end, two applications of camera zapping are immediately possible.
If a camera's location is known, and can be seen, and is stationary, a
tripod/rifle scope/gun sight laser system can successfully zap it, even at
distances greater than 100 meters. If a camera is roving, a golf scope/gun
sight laser can intermittently zap it by hand with little
effort.
DE-PRESENTATION
The
umbrella issue, on top of camera zapping, is perhaps most provocative of
all: how does one stop, or at least gain control of, representation of
oneself? Suppose, for example, you wanted to eliminate every instance of
your name that appears in a Google search. You could, in theory, contact
each website and demand they remove your name (though it's not clear what,
if any, leverage you might have). And of course, it would be naïve to
assume that every database with your name in it will be found with a
Google search.
One approach is simply to not care about one's
representation.
Another approach is to go through life avoiding
cameras, never submitting your name on any form, and only using cash. (I
know of at least two people like this.)
Whatever alternative or
optimal approaches may exist, it's clear that "de-presentation" is as
fundamental a force as re-presentation as we approach the brave new world
of massive databases and cameras everywhere. Some new and difficult issues
need to be addressed. Camera zapping may provide a robust metaphor for
these deeper issues and help to stimulate and provoke
solutions.
The author
gratefully acknowledges support from the Institute of Advanced Media Arts and
Sciences, Ogaki, Japan, and the IAMAS community, particularly
President Itsuo Sakane and Professor Hiroshi Yoshioka. Special thanks to
researcher Arnaud Pilpre of the Human and Object Interaction Processing
Group, Softopia Center, Ogaki, Japan, and a very special thanks to artist
Marie Sester.
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