LPR applications

License plate recognition - also known as automatic license plate recognition (ALPR) or automatic number plate recognition (ANPR) - is gaining more and more ground today.

LPR works by capturing the image of a license plate and transforming it into digital characters using optical character recognition (OCR) technology. The license plate number can be used as a unique identifier to assist the end user with security, management and information useful in the business environment.

The LPR can have different functionalities:

• Reading and recognition of license plates
• Day & Night, Vehicles stopped & in circulation
• Monitoring and access control of sites and parking lots
• Statistics of frequency of visits and average time of presence of vehicles
• Surveillance of public space intended for the Police

Its applications can be multiple:

• Roads / highways - traffic monitoring
• Public parking - entrances / exits and flows
• Private parking - access control,
• Car washes - frequency of passages
• Local authorities - traffic management and access control
• Transport & logistics - traceability and parking
• Military bases – detection of military forces

LPR applications include access control, law enforcement, parking and traffic management.

ACCESS CONTROL

Access control is one of the simplest applications in the management of vehicle entrances/exits. LPR is mainly used to control access to authorized or unauthorized vehicles in a parking lot or on a property, according to an authorized list. Shops and large retailers also use it to build up evidence in the event of fraud at their service stations, or to simplify the return of utility vehicle rentals

COMPLIANCE WITH THE LAW

In addition to access control, law enforcement agencies can benefit from the LPR. This is not only for license plate recognition, which makes it possible to identify unregistered or even stolen vehicles. It can also tag cars with unpaid fines or penalties. In extreme cases, it can even help authorities prosecute suspected terrorists and criminals.

LPR can also be used to search for stolen vehicles, wanted persons and drivers with suspended license.

MUNICIPAL PARKING

Managing parking in a city, especially in a rapidly growing city, is a real challenge. LPR can also be helpful in this regard. Manual verification of permits, lengthy checks, temporary parking all take up valuable time. ALPR technology simplifies the implementation of the parking system and improves overall efficiency, allowing police to quickly and easily check whether parking has been paid for (any method of payment), check illegally parked vehicles and better target interventions.

TRAFFIC MANAGEMENT

The data generated by LPR systems can provide valuable information to city authorities to manage and improve traffic. The data collected by LPR systems can be used for urban planning and traffic management by analysing the volume and movement of vehicles. Journey times can be determined by analysing the tags of a number of LPR camera locations. In this way it will be easy to understand delay patterns and alerts regarding abnormal volume of passages or slowdowns, or incidents to be handled by public safety personnel.

OTHER APPLICATIONS

Other applications include border control and tunnel surveillance. In addition, data provided by LPR can be used for security and business intelligence purposes. In casino visitor monitoring, LPR can be used to check for prohibited visitors or players. Supermarkets can use LPR to alert staff to visitors requiring assistance (disabled or visually impaired customers). For transport and logistics activities, the traceability of vehicles in transit or in parking is an essential component of safety and productivity. Automatic plate reading is almost essential for flow control and fleet management.

Camera: a key element of LPR

The components of an LPR system include a surveillance camera, an LPR engine running on a suitable processor, storage media and other optional items such as IP relays and audio devices.

The camera is the most important element for identifying and reading signs in an outdoor environment, 24 hours a day, 7 days a week, throughout the year. That's why you need a robust, state-of-the-art camera.

An ordinary, inexpensive camera will not suffice. You'll see demos with cheap cameras with slow mono-band images or off-road traffic with good ambient light - but the system must work 24 hours a day with all the qualities of the cards. The camera must be an LPR camera, equipped with two lenses or a high quality CCTV camera, which must be properly configured.

Cameras used in LPR applications: Whether they are dedicated to LPR or license plate recognition - you have to meet different requirements to get the maximum result. The key point to consider is that the image recorded by the camera must be clear and accurate enough for the recognition process to work efficiently.

Camera installation in LPR systems

Correct installation plays a crucial role in license plate recognition. The quality of the installation determines the performance and efficiency of the system. During installation, the correct configuration of the camera is particularly important. Various factors, such as the positioning of the camera and the angle at which it is installed, will affect the quality of the captured image and thus the performance of the recognition process.

DISTANCE

The distance between the vehicle and the camera varies depending on the location and user needs. An ALPR camera can read distances of up to 35 to 40 meters. The longer the reading distance, the more variables can come into play, such as queued cars.

As a rule of thumb, the capture distance should be about three times the installation height of the camera. For example, if a camera is mounted 3 meters high to prevent vandalism, the capture distance should be 9 meters and more.

ANGLE

The angle at which the camera faces the vehicle is also important. The user has to take into account two criteria: the vertical angle between the longitudinal axis of the camera and the plane on which the vehicle is moving and the horizontal angle between the longitudinal axis of the camera and the longitudinal axis of the vehicle. The smaller the angle, the better. The main rule is to place it within 30 degrees between Pan and Tilt.

POSITION

When you position the camera near a security fence, it should be behind, not in front. The vehicle may pass through the field of vision before stopping. If, for any reason, the plate is misread, it can never be read again. If the barrier goes up, keep in mind that the barrier arm could obstruct the license plate of an oncoming vehicle.

If the camera cannot be positioned backwards enough to better manage the traffic, two cameras can be used. Directed towards the entrance to cover extreme angles, they will help us with bumpers and ground markings. Sometimes the white or yellow horizontal lines can encourage vehicles to approach at the right angle.

So, each department has different objectives and requirements and it is important that the installer fully understands these requirements when thinking about an LPR system. Think about when vehicles will be monitored and plan for license plates to always be in that field of view (or not). Go on site to observe and record images with vehicles passing through the point of detection to understand the variability in vehicle positioning. Take into account the speed of the vehicle, if measures are needed to slow down traffic or to adjust their position in the field of vision.