LYING in his helicopter, Sgt. Frank Sheer of the Orange
County Sheriff's Department in Southern California can be
literally miles from the action. But that does not mean that
he and his co-pilot do not know what's going on. In fact,
Sergeant Sheer says they often have a clearer picture of a
crime scene than the officers who are there.
"We'll be tracking a suspect on a hillside from the
helicopter," said Sergeant Sheer, the chief pilot in the
Orange County force, "and the deputies climbing up it will be
saying to us, `There's nobody here.' We've actually had them
step on a guy who pulled up a bush for cover."
It's not just having a bird's-eye view that gives Sergeant
Sheer and many other airborne police officers, rescue workers,
military personnel, and television news and movie crews almost
paranormal vision. Nor is it simply advances in optics and
cameras. Ultimately they all rely on complex camera
stabilization systems that mix mechanical and electronic
technologies to produce steady images, even at high
magnification, from inherently unsteady craft like helicopters
When officers pursued O. J. Simpson along the freeways of
Los Angeles eight years ago, a covey of police and television
news helicopters tracked him with stabilized cameras hanging
at the sides in their distinctive ball-shaped pods. But most
helicopter surveillance is not that dramatic. If the Orange
County Sheriff's Department needs a car discreetly followed,
Sergeant Sheer can keep tabs on it from 3,000 feet up and a
considerable distance behind — a position that would leave
most motorists unaware there was a helicopter around, let
alone watching them.
New systems built around all-electronic motion-sensing
technologies are so stable that only the horizon and haze
limit how far away observers can be.
The use of airborne stabilized cameras to create films or
follow athletes in action attracts little controversy. Nor
does anyone dispute that the systems allow police officers to
capture criminals or rescue people. Some privacy advocates,
however, are concerned that the recent proliferation of
airborne cameras and the growing capabilities of new systems
may mean that anyone who steps outside may unknowingly be a
target of an aerial eye. Outdoors, there may no longer be any
place to hide.
"Because technology affords police what amounts to
superhuman vision, that doesn't mean we lose all expectations
of privacy," said Barry Steinhardt, the director of the
American Civil Liberties Union's program on technology and
liberty. "There are lots of innocent people who are going to
have their privacy invaded — observed naked in their backyard
sunbathing from far away."
There is a long history of efforts to produce steady
airborne pictures. But in the early years, the results were
for the most part dismal.
Steven Poster, the president of the American Society of
Cinematographers, recalls his first attempt at photography
from a helicopter, in the late 1960's. "It was an Illinois
State Fair, and the stabilization came from a rope tied around
me to the helicopter," Mr. Poster recalled. "I quickly
realized that this was not a very good system."
While more sophisticated systems existed back then, they
did not differ much from Mr. Poster's rope. Known as side
mounts, they generally relied on bungee cords and the user's
body to isolate the camera.
By the 1980's Mr. Poster was a director of photography for
feature films and television advertisements, and he had found
an answer to his aerial photography problems with a system
made by Wescam, a company now based in Burlington,
"It's the best way to stabilize a camera," said Mr. Poster,
who has used the system in films like "Stuart Little 2," which
is to be released this summer.
The Wescam system used by Mr. Poster's film crews is
remarkably similar to the original Wescam developed in the
early 1960's by a Canadian subsidiary of Westinghouse as a
battlefield surveillance tool for the Canadian military.
(Wescam is short for Westinghouse camera.)
Eliminating the vibration from the helicopter was the first
step and the easy part. The Wescam ball is attached to a
helicopter or airplane through a shock absorber that uses
springs and other damping materials. "It is tuned for the
natural frequencies of helicopters," said Mark Chamberlain, a
mechanical engineer who is president and chief executive of
But eliminating the vibration does nothing to limit three
other kinds of movement by the camera: pitch (plunging up and
down), yaw (rotating around a vertical axis) and roll (the
side-to-side rotation that creates a moving horizon).
To deal with these kinds of movements, inventors of the
original Wescam turned to large gyroscopes, which create
inertia. It is like strapping a large boulder to the camera to
stabilize it, yet without all the weight that a boulder would
Inside the camera ball are three gyros oriented to offset
each of the three types of unwanted motion. Motors attached to
the camera mount allow an operator within the helicopter to
view images from the camera on a video monitor and point the
camera as needed.
The gyro stabilization system proved so steady that it has
not significantly changed over the last three decades. But the
system has one significant drawback: the gyros require
That is not a problem for the movie industry, which rents
the camera systems for short periods. (Other companies,
including Gyron Systems International, Tyler Camera Systems
and Spacecam Systems, also offer stabilized motion picture
cameras.) But the need for maintenance made the systems
largely impractical for full-time use by police, the military
and television stations.
After Mr. Chamberlain led a management buyout in 1987 of
the engineering company that had come to control the Wescam
technology, he turned its attention to introducing a
technology that was more robust.
Instead of providing stability, its three gyros wobble
slightly when the rig changes directions. Sensors measure the
wobbling and feed the data to microprocessors that in turn use
high-speed electric motors to move the camera and offset the
The second-generation technology — what Mr. Chamberlain
calls a sense-and-react system — has only about half the
stability of the original Wescam, so it cannot be used with
lenses with very high magnification. But for the Orange County
Sheriff's Department, it is unquestionably an improvement over
using hand-held binoculars from a helicopter.
"At 1,500 feet we're not reading license plates, but we can
tell if it's a man or a woman on the ground," Sergeant Sheer
Like many systems used by police forces, one of the two
Wescam systems owned by Orange County has a night vision
camera that creates images by capturing the infrared radiation
emitted by warm objects, including people.
But a United States Supreme Court ruling last June has
forced the Orange County Sheriff's Department and other police
forces to change the way they use those thermal imaging
cameras. The court said that the police could not train
thermal imaging cameras on private homes without a
Mr. Steinhardt of the A.C.L.U. said he would like to see
legislators, rather than the courts, come up with specific
rules for police use of helicopter camera systems. The
A.C.L.U. does not oppose the use of cameras "under the rare
circumstance that the police might be legitimately in pursuit
of a hot suspect," he said.
"But in the end, that's not how it's going to be used," he
added. "It's going to be used in ordinary law enforcement, and
that's very different."
It is also being used from ever greater distances. Four
years ago Wescam introduced a third stabilization system that
combines the reliability of cameras like those used by the
Orange County Sheriff's Department while offering even greater
stability than the original system. It replaces the spinning
mechanical gyroscopes with fiber-optic gyros, which use bursts
of laser light to calculate movements by the camera system in
Once measured, the movement is also offset with a new
technology known as magnetic torque motors that can apply a
force in a specific direction but allow free movement in all
Not only is the new system much faster, said Steven
Tritchew, Wescam's chief technology officer, but it will also
provide a steady image with the magnification of "any lens
being made." Practically speaking, atmospheric haze and,
ultimately, the impossibility of seeing beyond the horizon are
the only limits on how far it can see. "We call it the
— we can see a long way," Mr. Chamberlain said.
Certainly Lt. Keith Howland, a mission commander and
tactical coordinatorbased at the Naval Air Station in
Brunswick, Me., noticed a big difference after an old system
in his P-3 Orion surveillance airplane was replaced by a
turret with Wescam's new technology about a year ago. "You
wouldn't even place them in the same universe," he said.
While on patrol, Lieutenant Howland said, he can watch
events on the ground "well outside of visible range."
Like many civilian cameras, the Wescam on the P-3 can be
aimed by punching in Global Positioning System coordinates.
Software allows it to track moving objects on the ground more
or less automatically.
While his aircraft's camera system cannot match the broad
sweep of surveillance satellites, Lieutenant Howland said that
it had many other advantages. "Basically we can be in real
time on a target, see things at the moment they happen, and
report it," he said. "It's live video versus a picture."
The systems can be costly, with the most advanced models
costing as much as $650,000. But Wescam plans gradually to
introduce variations on the new technology into all its
markets, potentially giving police departments the same
farsightedness. (The Raytheon
Company recently introduced a fiber-optic
gyro-stabilization system of its own. FLIR
Systems of Portland, Ore., is also among the companies
that make stabilization systems for police and military
Mr. Chamberlain suggested that the most advanced technology
might next go to an even more demanding customer than a police
department chasing criminals or a military unit tracking
terrorists: the broadcast news industry.
"From a pure image point of view, the military want
uninterrupted imagery," he said, "but if it bounces a little
bit once in a while or there's a little bit of fuzz on it from
interference for a second or two, that's O.K. In the broadcast
industry, if it jiggles a little bit or has a bit of fuzz when
someone's crossing the finish line, well, you might not get
WATCHFUL EYE - Stabilized cameras can track subjects
from the air. Above, an infrared camera on a Coast Guard plane
watched drug smugglers off Florida. A conventional camera
caught two men in a park in Orlando.