Technology services company telent discusses different uses for Automatic Number Plate Recognition
Automatic Number Plate Recognition (ANPR) is a supervision technology that was developed in the UK in 1976 and was first used by the British Police in 1979. ANPR is often referred to as Automatic Vehicle Identification (AVI), Car Plate Recognition, NPR and LPR systems.
The technology uses optical character recognition software that can be connected to a number of different CCTV cameras to scan images reading the number plates of motor vehicles. The technology is constantly being developed and its usage is evolving. Currently, it is mainly used in security and police tracking work. Used widely throughout the world ANPR is most advanced in the UK, USA and Europe. The recognition cameras can also be used as speed cameras, in traffic management systems and is also proving popular in toll collection and enforcement systems having been adopted for the London Congestion charge.
ANPR software ‘engines’ can accept images from monochrome, colour and infrared cameras. The colour and monochrome cameras are suitable for clear daylight conditions but are less effective at night as they suffer from the effects of headlight glare. Dual systems are common where the client may require an overview image of the complete vehicle as well as the number plate capture. Such systems would have a combination of an infra-red camera and a standard camera often mounted in a common housing.
The automated optical recognition and subsequent recording of vehicle registration plates has been something CCTV manufacturers have strived to achieve. However, only recently has that camera technology been fused with advances in computer processing power and the development of ‘clever’ algorithmic software to finally deliver such an important solution. The newer ANPR systems use high definition digital colour cameras to capture detailed images of the target vehicle.
There are a number of markets that ANPR is now used in.
Homeland Security/Law Enforcement encompasses many areas, including: Police Mobile Systems (in-car), Police Town Centre Fixed Systems, Customs and Border Control, Ports and Airports Surveillance and Control, Military Usage, Rapid Deployment Systems, CT – Covert and Remote Systems.
Instant highly accurate recognition and rapid response are the key features in Homeland Security/Law Enforcement.
All ANPR equipment used in this context in the UK must comply with the National Association of Chief of Police Officers Automatic Number Plate Recognition Standards (NAAS). NAAS exists to enable development and integration of ANPR systems used by the England, Wales and Northern Ireland Police Forces, allowing compatibility across Police Forces and compliance to common national standards. Economically, ANPR may be added to existing CCTV infrastructure such as local council surveillance systems in town and city centres etc.
Hotlists can be checked in real-time as a vehicle passes – or data can be recorded and transmitted to the Police Back Office (BOF2) or the third party BOFs for wide area collation and data mining. Colour overviews or video clips can be recorded and data can be transmitted by various methods including Wireless LAN and 3G. All reads are stored with GPS co-ordinates and instant mapping shows where and when vehicles were read for simple visual analysis of data.
Intelligent Transport Systems
The Intelligent Transport Systems (ITS) sector is the fastest growing market segment internationally. With a global increase in traffic congestion and associated pollution, new journey time monitoring systems and congestion charging schemes are being implemented around the world.
Such systems must be able to handle multiple lanes of traffic and there are a number of cameras on the market that can read two lanes from a single device, reducing installation costs.
The ANPR processing can take place inside the camera transmitting the results back to base using fibre or the 3G networks. This greatly reduces installation costs (no roadside equipment) and can also reduce bandwidth requirements since only the plate read and any required associated images need to be transmitted.
Journey time monitoring is a most meaningful measure of a network’s performance and can provide valuable information for ITS Systems. Origin and destination matrices provide demand information, input for traffic models and support for multi mode journey options.
ANPR cameras can be fixed to gantries or other roadside furniture to identify vehicles at key points in the network. Each camera is connected to ANPR software via a roadside cabinet or directly within the camera. Data is transferred to the central location every few minutes, hours or daily, according to data needs.
Security applications can be the most challenging use of ANPR as 100 per cent accuracy is required. Cameras are positioned at site entrances and barriers; LED signs or traffic lights are often employed in association with such systems.
The systems are required to read all plates of approaching vehicles and permit access to employees or pre-approved visitors or guide them to specific lanes for fast track entry.
Exact entry and exit records are kept of all vehicle movements for later analysis. Many systems can be connected to intelligent Variable Message Signs (VMS) to display ‘welcome’ messages to visitors.
Staff hotlists can alert security to dismissed staff or known troublemakers – or simply warn of important deliveries. Alarms can be visual or audible. SMS messages or automatic e-mails can be sent to selected staff warning of important visitors – or indeed intruders.
Access control and timing options can permit or prevent access of specific vehicles at specific times. Car sharing is also catered for with groupings of cars managed by the system.
The system can also be linked to several under vehicle scanning systems where plate details are stored with the vehicle scans – and also Nuclear/Fissile material scanning systems.
In such systems short-range pole mounted cameras or bollard cameras are often deployed.
The value of ANPR as a crime reduction tool is well documented. ANPR increases the chances of criminal capture as it can check and verify with a database many times faster than a manual process.
ANPR’s use in criminal investigations, to trace journeys of suspected vehicles or known offenders, has increased dramatically as police forces improve their regional coverage. Over this period, ANPR has played its part in many high profile arrests and convictions.
ANPR data is a rich source of information that has the potential to add considerable value to both post-incident investigation and proactive intelligence analysis in many areas, including counter-terrorism, cross-border investigation and major crime.
The use of ANPR for journey time prediction has certainly become more popular in recent years. The ability to accurately predict motorway and arterial travel times is a critical component for many ITS applications to assist in combating the problems of congestion and pollution.
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