Brazil’s ‘Robocops’ Spot Bad Guys a Mile Away With Face Recognition Sunglasses
By Dialogo May 20, 2011
“GOOOOOOOL!!” The crowd inside São Paulo’s Morumbi Stadium goes wild.
Amid the revelry, a military police officer scans the crowd. His mirrored
sunglasses aren’t just shading his eyes; they’re comparing the thousands of fans
against a database of criminals and missing persons at a rate of 400 faces per
One face in the crowd makes a match to the million-strong database. A
blinking red light goes off in the officer's field of vision, and the facts appear:
This man is wanted for murder.
Now the officer must decide what to do. Where to apprehend the suspect? Does
he need backup? He weighs his options with the potential disruption to the crowd.
It’s Robocop, Brazilian-style.
With crime on the rise in major cities like São Paulo and Rio de Janeiro,
some greeted the news that Brazil would play host to not only the 2014 World Cup but
also the 2016 Summer Olympics with skepticism. To assuage those security concerns,
the country is ramping up its technological crime-fighting capabilities.
“The Military Police is on a constant search for new technology and equipment
that can help and complement activities linked to the protection of citizens,” said
Maj. Leandro Pavini Agostini, chief of Sao Paulo’s Military Police.
Face recognition technology is used in a variety of applications around the
world, including automated border crossings in Great Britain, Finland, Portugal,
Germany and Israel, and at passport and visa issuance locations in the United States
and Great Britain.
How face recognition works
The technology uses one of two methods: facial
geometry comparison or eigenface comparison.
Facial geometry takes the distance between the eyes and measures facial
features and angles from that point of reference. Eigenface compares the scanned
faces to a database of about 150 abstract “archetypal” faces.
The rate of false positives is about one in 1,000, said Dr. James Wayman,
director of the National Biometric Test Center at California’s San José State
“The other side of the coin is that the false negative rate can exceed 10
percent, depending on how carefully imaging conditions can be controlled,” Wayman
Optimal imaging conditions for face recognition are the same as for passport
photos: No smiling or frowning, no raised eyebrows or squinting. Eyes must be
looking directly at the camera. And it’s not just expressions that must be
controlled. The background should contain no shadows, texture, lines, or curves, and
should be one color.
Any departure from these conditions causes the search algorithm to perform
poorly, meaning the false negative rate increases.
Maintaining these standards of accuracy in a stadium of inebriated, cheering
soccer fans can be more than a little difficult. However, as Wayman points out,
casinos have been using face-recognition technology since the late 1990s to spot
Proponents of the technology say it has performed well even against aging,
weight changes, or changes in hairstyle or facial hair.
Application in the field
Pavini said the glasses help identify people at a distance of 50 meters with
normal lenses, and 20 kilometers with good lenses.
“I know of no existing applications of automated facial recognition that
operate beyond about five meters, and the five-meter application had stationary
cameras with good lenses,” he said.
In São Paulo the technology has passed tests with a simulated database with
flying colors, said Pavini. Now it’s being used with the official police database.
He said the technology should be implemented right away, prior to the World Cup.
“If further tests are successful, we suggest acquiring the technology
immediately for installation in the more than 270 cameras operated by the Military
Police in São Paulo; in cars, and with glasses for police officers to wear at public
events,” Pavini said.
“This technology makes it possible to search with better agility and without
initial contact with suspects, adding to the security of police officers and those
around them,” he said.
That should make about 500,000 tourists coming to Brazil for the upcoming
sporting events feel a lot safer.