For many years I was under the impression ALPR was only used to alert officers of a hot tag. That is not the case.
In addition to the real-time processing of license plate numbers, ALPR systems in the US collect (and can indefinitely store) data from each license plate capture. Images, dates, times and GPS coordinates can be stockpiled and can help place a suspect at a scene, aid in witness identification, pattern recognition or the tracking of individuals. Such data can be used to create specialized databases can also be used to compile personal information on individuals such as journalists suspected gang members, employees of a business, patrons of a bar, etc., and be shared by E-mail or portable flash media.
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United States http://en.wikipedia.org/wiki/Automatic_number_plate_recognition
Jurisdictions in the U.S. have stated a number of reasons for ALPR surveillance cameras, ranging from locating drivers with suspended licenses or no insurance, to finding stolen vehicles and "Amber Alerts". With funding from the insurance lobby, Oklahoma introduced ALPR with the promise of eliminating uninsured motorists, by integrating it with its existing PikePass hybrid RFID/OCR toll collection system, and unmarked police vehicles used for intelligence gathering. [26] [27] Oklahoma replaced all license tags with ALPR-compatible plates in 2009. In Arizona, insurance companies are helping to fund the purchase of ALPR systems for their local law enforcement agencies to aid in the recovery of stolen vehicles.
Other ALPR uses include parking enforcement, and revenue collection from individuals who are delinquent on city or state taxes or fines. The technology is often featured in the reality TV show Parking Wars featured on A&E Network. In the show, tow truck drivers and booting teams use the ALPR to find delinquint vehicles with high amounts of unpaid parking fines.
A recent initiative by New York State deployed ALPR systems to catch car thieves by tracing suspect plates back to forged documents. Police from Albany, New York also scan vehicles in their parking lots to check visitors for warrants.[28]
In addition to the real-time processing of license plate numbers, ALPR systems in the US collect (and can indefinitely store) data from each license plate capture. Images, dates, times and GPS coordinates can be stockpiled and can help place a suspect at a scene, aid in witness identification, pattern recognition or the tracking of individuals. Such data can be used to create specialized databases that can be shared among departments or individuals (such as insurers, banks or auto recovery "repo-men".[29]) Specialized databases can also be used to compile personal information on individuals such as journalists[30] suspected gang members, employees of a business, patrons of a bar, etc., and be shared by E-mail or portable flash media.
From time to time, states will make significant changes in their license plate protocol that will affect OCR accuracy. They may add a character or add a new license plate design. ALPR systems must adapt to these changes quickly in order to be effective. For the most part, however, the North American design will be based on a variation of the "Zurich Extra Condensed" font.[31]
Another challenge with ALPR systems is that some states have the same license plate protocol. For example more than one state uses the standard three letters followed by four numbers. So each time the ALPR systems alarms, it is the user’s responsibility to make sure that the plate which caused the alarm matches the state associated with the license plate listed on the in-car computer.
