What do you need to know before choosing a mobile system for license plate recognition?
According to statistics of the International Association of Chiefs of Police, up to 70% of serious crime is somehow related to motor vehicles. It is not just car thefts but also their use in committing crimes. Analyzes and statistics show that license plate recognition systems help not only in locating stolen vehicles, but also in searching for missing persons and investigation of kidnappings or robberies.
In spite of critics pointing out to the risks of privacy violations, the automatic license plate recognition (ALPR) market is growing by more than 10 percent each year and is expected to reach 4.25 billion by 2023. This is more than double compared to 2016.
Automatic license plate recognition systems are also used to check if parking or toll has been paid, or to allow access to certain zones. However, growing the most are so-called mobile ALPR systems becoming the standard technology of police cars around the world.
However, not every system can meet the demanding requirements of the police. License plate recognition in garages of shopping centers where cameras are not exposed to bad weather and the car always stops in front of them is relatively easy. It is much more difficult to recognize license plates from a moving vehicle, especially if the other vehicles are moving, too. In this scenario, conditions are constantly changing. Be it the speed of movement, light intensity (day, night, public lighting, lighting from other vehicles, etc.) or weather, they all significantly affect visibility.
Here are three differences distinguishing professional from amateur ALPR systems
1. The right type of shutter and infrared backlighting
Vehicle-mounted cameras used for mobile license plate recognition have the so-called global shutter preventing image distortion and infrared illumination allowing them to operate at twilight or at night.
However, you shouldn’t have unrealistic expectations. Even with specialized cameras, you will not achieve a 95 percent success rate, because license plates may be extremely dirty, or visibility in the bad weather may be so low that the system simply can not read the license plate.
Also, remember that for the best results the camera should be mounted on the car’s exterior rather than inside the cabin. Otherwise, the glass absorbs much of the infrared light and the recognition efficiency drops sharply.
2. Focused on a selected spot
Specialized mobile ALPR cameras focus only on what really matters. They do not try to capture wide-angle shots because that would record too many unnecessary pixels. To analyze excessive data volumes would be inefficient, if not absolutely impossible. On the contrary, for optimum result, the camera must be fixed to scan one or no more than two lanes and capture images only at a distance of 12 to 15 meters.
The aim is to focus only on areas in which vehicle license plates are located. So, it’s far from the truth that you can process just about any passing car video with an ALPR software and think that the system would identify license plates. You will probably achieve some success, but it’s going to be far from a professional solution.
3. Integration with the environment
Today, there are quite many ALPR vendors, but most of them only sell a license plate recognition software alone or in a package with a camera. However, such a solution usually does not satisfy more demanding requirements of law enforcement or security agencies.
Some companies are developing comprehensive solutions for intelligent police cars. ALPR is one of the key elements of such solutions, but they also integrate other useful technologies. They are able to automatically check the recognized license plates against various databases (such as a stolen or uninsured vehicles database, or check the toll payment), track the position of a police vehicle, improve communication with the head office and also record video for purposes other than ALPR.
An experienced vendor is able to provide a complete platform in which various technological systems of the police car communicate with each other and function flawlessly to ensure automatic updates and ultimately higher police work efficiency and thus higher citizen safety.