For many installers 2003 will be the year that Automatic Numberplate Recognition really takes off. This is a fast growing sector with systems already installed as part of the access to many car parks. But it is important for installers to avoid the common pitfalls...
There is a big opportunity for installers to win new business in Automatic Numberplate Capture and Recognition in the coming months – the technology has had some high profile successes and looks certain to grow significantly – but it will also be easy to make costly errors and waste your profits in putting them right.

For most installers this is a new discipline, with engineers still at the start of the 'learning curve'.

The good news is that there are opportunities for ANPR systems at every level, with applications from your local health club, to town centre car parks, right up to major urban projects.

So for the majority of installers who are new to ANPR it is perfectly possible to start at the basic levels, master the craft, and expand upwards into potentially high value contracts. There are also significant retro-fit opportunities to sell ANPR solutions to existing customers or as a lead-in to new clients.

Installation priorities
Wherever you pitch your business – entry, inter-mediate or advanced systems - the best advice is to learn from other people's mistakes, not your own.

Over the last three years, as the technology has developed, we have been working with some of the pioneer installers and end-users to fit ANPR systems that really work (and it is surprisingly easy to fit systems that don't really work!)

Here's what we've all learned:
The quality of the image of the number plate itself is the most important factor. Every aspect of your installation should be designed with this in mind.

As you look at more advanced installations, using sophisticated software to process the number plates, the quality of the captured image that you provide becomes even more important.

Your system will also have to deal with a totally different set of image-quality challenges – dirty number plates; fast moving vehicles; vehicle headlights; and of course all the traditional challenges of changing light and conditions.

Pitfalls to avoid

1. Use dedicated cameras
Not surprisingly some end users have pushed installers to fit ANPR cameras which can play a dual role. They want the camera to capture number plates and at the same time provide surveillance of the surrounding area ... As a rule this won't work.

The ANPR camera has enough difficulties to deal with when it is focused totally on capturing number plates – ask it to cover a wider area and it will be compromised. It will not be able to deliver high resolution images of the number plates and it will certainly not be able to cope with changing environmental conditions over time.

(Derwent have developed specific ANPR cameras which combine both a dedicated ANPR camera and a general overview camera into a single, dedicated unit.)

2.Camera positioning
Ideally site the cameras at pinch points or by control points such as barriers where vehicles have less opportunity to travel at speed or at angles to the camera. Consider traffic management issues to ensure clear line of sight from ANPR camera to numberplate at all times.

The camera should not be positioned too high above the road: the shallower the angle, the better. Ideally the number plate should be viewed from not more than 30°.

Take care about the position of the sun in relation to your camera during different parts of the day. Be aware of the sun's position during different parts of the year – summer vs. winter.

(Derwent have developed a simple software programme to calculate all relevant angles and distances from ANPR camera to number plate.)

3.One camera, one lane
Some installations have failed because a single camera has been set up to cover more than one lane (eg. in and out from a car park). Although the camera may be dedicated to ANPR use, by attempting to cover too wide an area image size and quality will not be good enough for consistent reliable capture on a 24 hour basis, particularly if the system is to be used with ANPR software.

4.The importance of Infra Red
Remember that Infra Red lighting plays a vital part in all ANPR systems, not just at night, but during the day as well. With ANPR systems visible light is filtered out and only IR light is used by the camera: this solves the serious problems with glare on the number plates from headlights, sunlight, light from wet roads etc. Using Infra Red in this way also helps overcome the issue of dirty plates.

Therefore good quality IR lighting is essential to provide good quality ANPR images – day and night.

5.Recording and compression
Beware of compressing images too much on your DVR as a way of extending recording periods. While compression is fine for many applications it works by cutting the file size of each image to save on memory. As a result , compression reduces the resolution of the image and can render the captured number plate unusable.

The degree of compression acceptable will depend on what the number plates are being captured for, speed of traffic etc. Simple review of pictures by the human eye will allow a certain reduction in quality.

The simple test is to play back the recorded images – Are they fit for the purpose?

6. Capture Vs Recognition
Although these two terms are often confused and sometimes interchanged, they are altogether different. Capture is used to refer to the process by which the CCTV camera captures the image and is primarily concerned with delivering a high quality image of the number plate. It does not refer to recognition or interpretation of the image in an intelligent manner.

Recognition refers to the intelligent software process of reading , recognising and analysing the captured CCTV image and using optical character recognition techniques to create an alpha-numeric data string of the characters on the numberplate. These can then be stored as a computer record. The computer record can then be retained, reviewed, compared to existing databases, and used to trigger commands such as opening barriers etc.

Identifying whether your project requires capture or capture and recognition at the early stage is essential.

Getting it right
In conclusion, no matter what your requirement, it is essential to have high quality images of the number plate on a 24/7 basis. This requires a combination of good installation practice, and high quality equipment.

The essential first step for the installer is to clearly define with the customer the purpose of capturing the number plate and the level of intelligence required.

Think carefully! As a general rule the higher the intelligence, the higher the final cost. It is always easy to over-specify, but considering your aim first will help reduce unnecessary costs as the project progresses.

Achieving effective 24/7 number plate capture and recognition is a complex task.

However with the correct integration of the elements and a clear understanding of the problems, achieving high levels of capture is possible. During initial discussions the installer has a good opportunity to warn the customer about the problems identified above – and to explain the advantages that a well installed ANPR system can deliver. We recommend firstly identifying the characteristics and level of intelligence of your specific project at either Entry level, Intermediate or Advanced. Doing this allows you to focus on the key issues and opportunities.

ANPR hardware

Derwent's REG is an example of the video capture technology available to installers. The unit combines the latest camera, optics, illumination and filter technology to provide clear images of number plates in both day and night conditions. To give installers greater flexibility, this technology is designed to operate independently as a number plate capture head in the case of entry level systems or in conjunction with software, for intermediate or advanced applications. Other manufactures such as Vista VNPR offer a complete solution for intermediate and advanced applications, combining both camera and software. Choosing you hardware and software partner is a critical step in making the most of the growing business opportunity.

Characteristics of ANPR systems

Characteristics of an Entry Level System
  • ANPR camera is additional CCTV camera
  • Integral part of CCTV system
  • Simple storage and retrieval mechanism often tape or DVR
  • Date, time and number plate are the critical element that may lead to an arrest
  • Event driven
  • Reference to data required chiefly upon event. i.e. theft, break-in, vandalism etc.
  • Images reviewed post event for re-active security.
Example – Warehouse: situated on an industrial estate, number plate capture can be used to ensure that any vehicles used during an attempted break-in are captured on camera, and subsequently traced by the police. The warehouse premises has a single entry and exit point. Characteristics of an Intermediate Level System
  • Requires intelligent PC based software based system
  • May require external trigger to release barrier, signal to traffic lights etc.
  • LED signage may be used to inform the driver that he has been recognised
  • Continuous reference to data required
  • Quick search, review and retrieval critical to the operation procedures
Example – Golf Club: The owners want to impress their guests with a superior level of service. Identifying the guest as they enter the club driveway, welcoming them on a clever LED signage ‘Welcome Mr White’ and opening the barrier as they approach the clubhouse. Not only does the system impress the guest, but it helps with tracking usage by denying access to non guests, securing the site against any possible burglaries and allowing the owner to track employees entry and exit times. Characteristics of an Advanced System
  • Requires intelligent be-spoke PC based software systems
  • Interaction with other database or sources of information may need to be co-ordinated
  • Extremely large capacity of storage and retrieval required
  • Complicated methods of interaction with other data systems
  • Critical to the success is the accuracy of the information
Example – Central London Traffic Congestion Scheme. Advanced applications tend to be Motorway, Police applications and local authority initiatives.

The growing market for ANPR

Following the success of congestion charging in central London, ANPR is going to be big news in many city centres. Publicity will have a positive effect on the market, with demand likely to grow rapidly among smaller, private users. Typical Entry Level: Security (capture only)
Systems ensure that if a crime is committed the number plates of any vehicles are captured and information can be supplied swiftly to police. Almost every existing CCTV system would benefit from an entry level ANPR system; ANPR camera is another camera in the system; opportunities immense. Intermediate Level: Access Control and/or Security (capture and recognition)
Intended to control or record the flow of vehicles in and out of barrier or entrance, as well as securing premises. The number plate is captured, intelligently read by ANPR software and then stored. Plate often compared to existing database and used to activate barriers, signs, alarms etc. Ideally suited for access control and security applications. Advanced Level: Intelligent Traffic Systems (capture and recognition)
Systems required to gather and act on specific information on the flow, speed or control of vehicles. Applications: speed cameras, congestion charging, car park management systems etc. Applications tend to be specific to client need and demand additional hard/software interaction with the client’s systems.