License Plate Capture is a fast growing security sector with many opportunities for firms already involved with CCTV. For security dealers, the ability to capture license plates - clearly, effectively and under virtually any conditions - is a strong selling proposition for which security end-users will pay top dollar. Security dealers can win new business and also service current customers by providing the added-value of license plate capture in existing CCTV projects.
It is easy to understand the need for effective license plate capture. Almost all criminal activity will involve vehicles at one point or another. (In the USA alone, a vehicle is stolen once every 26 seconds.) And because license plates are inherently linked to valuable identifying information, their capture can be indispensable as an investigative tool and as irrefutable evidence in a court of law.
Additionally, a myriad of applications exist in areas such as traffic management, tolling systems, parking, vehicle surveillance, counter-terrorism, border security, perimeter surveillance and access control, but the fallout from 9/11 has made license plate capture into a chief security concern for parties ranging from government to private enterprise.
License plate capture is an important capability that is poised for significant growth and has the potential to generate steady revenue streams for security dealers and integrators. The question then becomes: How?
Although license plate capture is still a new discipline for most security professionals, the good news is that there are opportunities for license plate capture systems at every level. Applications range from underground parking to gated communities to universities and continue up the scale to major urban projects. For the majority of security dealers who are new to license plate capture, it is sensible to start at the basic levels, master the craft, and expand upwards into high-value contracts. There are also significant retro-fitting opportunities to sell license plate capture solutions to existing CCTV customers or as a lead-in to new CCTV clients. However, security dealers who are not careful can make costly errors during the installation process. Here's how to make it simple:
The Key to Success
Wherever you pitch your business -- entry, intermediate or advanced systems - the best advice is to learn from other people's mistakes, not your own. Over the last few years as the technology has been refined, Extreme CCTV has been working with some of the pioneer integrators and end-users to fit license plate capture systems that get the plate - effectively, reliably and consistently.
From its extensive work in the field, the Extreme Engineering team has uncovered one common key to success in license plate capture: The quality of the license plate image is the most important factor. Every aspect of the installation should be designed with this in mind.
Using this as the central premise to effective license plate capture, Extreme CCTV recommends the following "best practices" to ensure a successful installation.
1) Use Dedicated Cameras
Not surprisingly some end-users have pushed security professionals to fit license plate capture cameras which can play a dual role. They want the camera to capture license plates and at the same time provide surveillance of the surrounding area. As a rule this will not work. The license plate capture camera has enough difficulties to deal with when it is focused totally on capturing license 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 license plates and it will certainly not be able to cope with changing environmental conditions over time. For applications that require overview vehicle surveillance AND license plate capture, Extreme CCTV Engineering has developed dual systems which combine both dedicated license plate capture camera and general overview camera into a single, integrated unit.
2) Properly Position the Camera
Ideally position the cameras at vehicle "bottlenecks" or by control points such as barriers where vehicles have less opportunity to travel at excessively high speed or at angles to the camera. Consider traffic management issues to ensure clear line of sight from camera to license plate at all times. The camera should not be positioned too high above the road and the shallower the angle, the better. Ideally the license plate should be viewed from not more than 35 degrees. Consider 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.
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 capture license plates, 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 intelligent software.
4) The Importance of Infrared
Infrared illumination plays a vital part in all license plate capture systems, not just at night, but during the day as well. With license plate capture systems, visible light is cut-filtered and only IR light is used by the camera. This solves the serious problems caused by glare on the license plates from factors such as headlights, sunlight and reflections from wet roads. Therefore, good quality IR lighting is essential to provide good quality license plate images -- day and night.
5) Recording and Compression
Avoid compressing images too much on your DVR. While compression is fine for many applications, it cuts 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 license plate unusable. The degree of compression acceptable will depend on factors such as the intended use of the license plate image and the speed of traffic. 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 to determine if they are fit for the purpose.
6. Capture vs. Recognition
Although these two terms are often confused and sometimes interchanged, they are altogether different. Capture refers to the process by which the CCTV camera obtains the image and is primarily concerned with delivering a high quality image of the license plate. It does not refer to recognition or interpretation of the image in an intelligent manner. Recognition - as in Automatic License Plate Recognition (ALPR) systems - refers to the intelligent software process of reading, recognizing and analyzing the captured CCTV image and using optical character recognition techniques to create an alphanumeric data string of the characters on the license plate. The data is saved digitally and may be delivered to a remote location using the internet, wireless broadband or other transmission system. The digital record can then be searched for, reviewed, compared to existing databases and used to trigger commands such as opening barriers. Although ALPR is still very new technology and generally reserved for high-end applications, the implications of ALPR are game-changing in nature.
Getting it right
In conclusion, no matter what your requirement, it is essential to have high quality images of the license plate on a 24/7 basis. This requires a combination of good installation and high-quality equipment.
The essential first step for the installer is to clearly define with the customer the purpose of capturing the license plate and the level of intelligence required. 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 license plate capture and recognition can be a complex task. However with the correct integration of the elements and a clear understanding of the problems, any diligent security professional can achieve highly effective license plate capture. During initial discussions the integrator has a good opportunity to advise the customer about the problems identified above -- and to explain the advantages that a well-installed license plate capture system can deliver.
About the author: Jack Gin serves as president and CEO of Extreme CCTV, a leading manufacturer of CCTV products for night vision and unique installations.