Did you know that police cars these days are now outfitted with cameras that can automatically scan all license plates within their visual range? Cameras mounted on a patrol car driving 80 mph can capture plates from cars driving the opposite way traveling at the same speed. Side-mounted cameras can be used to collect plates in a parking lot as the officer cruises leisurely back and forth through the lanes! Automated License Plate Recognition (ALPR) technologies mounted on police cars and various stationary sites are vastly improving the monitoring capabilities of the police force, and pissing off civil rights groups just as effectively.
The goal behind using ALPR monitoring is to track criminals. A “hot list,” provided by the FBI, is downloaded every day. The list includes perpetrators of all kinds, including illegal drivers such as those with suspended licenses or without insurance, but also more hardened criminals with warrants. They even track sex offenders. If a wanton criminal or a stolen vehicle turns up, the system notifies police who can then react quickly. In addition to spotting criminals, the data collected by the cameras can be mined in the event of a major incident such as a terrorist attack. Law enforcement officials could go back and see who was in the area at the time of the attack. The automated system is capable of scanning 10,000 license plates per hour and running checks on 2,000 to 2,500 of them against the "hot list" in a 10 hour shift. By comparison, the fastest police officers run about 100 plates per 10 hour shift. And the cameras are better at their job–they don’t tire at the end of their shift. Cruise shotgun with British Columbia's Sergeant Rick Stewart in the video below for a demonstration of ALPR technology. Awesomely, he actually gets a hit during the taping: a stolen vehicle involved in an armed robbery.
The plate trackers were developed in 1992 at Cambridge University in the United Kingdom to help track terrorists. Several different technologies are combined to produce the system's automated sophistication. A platefinder firmware continually searches the camera’s field of view for license plates. Once a license plate is detected the dual lens camera is activated, capturing images in both visible and infrared light. The infrared lens enables the camera to capture the plate in all kinds of weather conditions and even in complete darkness. A triple flash technology is also used that varies the flash, shutter, and gain settings over multiple images to adjust to different light and weather settings. A computer selects the best image for processing and that image is then read by an optical character recognition engine. The OCR engine can be generic or customized to the style of license plate found in a particular state or country. Because plates come in all shapes and sizes a good OCR engine will be flexible, reading plates from skewed and off-axis angles, and having different sizes, syntax rules, and designs. Processors will then take the data and store it in multiple formats for different types of downstream analyses.
Along with police vehicles, the cameras are also being mounted onto stationary sites such as toll booths and speed monitors: those roadside panels that tell you, “You’re driving this fast.” During last year’s World Series, San Francisco’s law enforcement used ALPR to monitor cars in the vicinity of AT&T Park. The San Francisco Chronicle recently reported that the city’s crime fighters have placed the cameras on six of their cruisers–that’s adding to the ten which already had them. As of this time last year, Los Angeles had 26 cameras.
At $20,000 a pop, the plate scanners aren’t cheap. But the increased monitoring efficiency and accuracy make them well worth the cost to law enforcement personnel. A study performed by the Association of Chief Police Officers concluded that using the cameras increased arrest rates in the UK ten times the national average.
Big Brother Never Sleeps
Not surprisingly, the increasing use of automated plate recognition to track drivers has raised the ire of the ACLU and other privacy advocate groups. In addition to a general distaste for being monitored all the time, the major objection being brought against plate recognition technology is the possibility that the data might be used for purposes other than tracking criminals. A recent article in Time described a hypothetical divorce case where the movements of a person could be used as circumstantial evidence to argue adultery. Law enforcement officals everywhere are doing their best to assuage these sorts of fears. Sergeant Dan Gomez, who runs the LAPD’s Tactical Technology Unit, emphasized that their license plate data is heavily guarded with strict protocols that an investigator must go through if he wants to follow up on a particular car.
Look, I think the technology is great. By all means, nab the bad guys. But I’m also thankful that we have groups like the ACLU that raise these important questions that I’m sure most of us share. If science is too important to be left to scientists, technology is too important to be left to those who make it. In my opinion, the world really is looking more and more like Orwell’s “1984." It's probably a good thing, from time to time, to give Big Brother a punch in the nose.