imaging and machine vision europe february/march 2011
www.imveurope.com
Image courtesy of ProPhotonix
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traffic and transport On the road again
Greg Blackman looks at some examples of intelligent transport systems in use for traffic monitoring and enforcement
Congestion is something most major cities experience to some extent. Last summer, news from China reported a traffic jam stretching 100km and lasting nine days on a trunk road into Beijing. Congestion charge schemes are in place in London, Singapore and Stockholm in an attempt to dissuade drivers from travelling in the cities between certain hours. The schemes use electronic toll collection or automatic number plate recognition (ANPR) to invoice vehicle owners without stopping the flow of traffic. Intelligent transport systems (ITS), such as the congestion charge scheme, are springing up to monitor traffic flow, for traffic enforcement, for automatic tolling and for security purposes. In China, the authorities have been investing heavily in ITS: according to camera provider Allied Vision Technologies (AVT), in Q4-2009 alone 1,063 ITS projects worth just over RMB $2bn (US $33m) were underway throughout China, including 384 in traffic light control systems, 238 in law enforcement, 238 check-points and 203 traffic surveillance projects. AVT is currently involved in multiple ITS projects in five major metropolitan areas in China, in partnership with China Daheng, its local distributor. Paul Kozik, product marketing manager at AVT
Canada, explains that machine vision cameras, which are often used in these traffic scenarios, are well suited, because they are so adaptable to different peripheral components. ‘A lot of traffic system engineers will build a solution from the ground up,’ he says. ‘Therefore, it is beneficial for the cameras to have many triggering options and the ability to connect different lenses or pan- tilt mounts. Machine vision cameras have these types of capabilities, because that’s the common scenario in other machine vision applications.’
Freeflow tolling ANPR is at the centre of a lot of ITS projects and many ITS cameras will include onboard
The London ring of steel, a network of ANPR cameras, monitors vehicles entering the city
ANPR processing capabilities. French company Survision provides systems for freeflow tolling – enforcing the toll without halting the traffic – using ANPR technology to invoice both subscribers and non-subscribers using the highway. This type of system, for example, is installed on the M50 in Ireland. According to Jacques Jouannais, general
director of Survision, this type of ANPR system will come into force in many countries in Europe within the next three years; all EU countries now have the option of putting in place a truck tracking system, called ecotax, by the end of 2013. An ecotax is already in place in Germany and The Netherlands and will be implemented this year in France. ‘All of these projects rely on ANPR technology,’ says Jouannais. ‘The use of this technology will therefore be widespread – just within France, for example, we are talking about 300 gantries and more than 1,000 cameras.’ The key vision requirements Jouannais
identifies for traffic installations are sensitivity, speed and efficiency. The cameras need to be sensitive to infrared, as the number plate is read in monochrome under infrared illumination in most cases. Survision’s ANPR cameras incorporate Sony FCB-EX20DP camera heads, which have a high sensitivity even above 800nm (within limits – above 950nm is outside of the sensor’s range). One of the key requirements of ANPR is to be
able to recognise the plate even under difficult lighting conditions. ‘As a system integrator, we need to have tight control over all of the camera’s parameters – the zoom, focus, gain, white balance, etc, all need to be controlled [to regulate the light reaching the sensor],’ states Jouannais, adding that the Sony modules provide that level of control. The parameters are controlled automatically onboard the camera, using Survision algorithms created specifically for the Sony FCB-EX20DP models. US company Pleora Technologies has been
involved in a number of major automated tolling projects in North America, Europe, and Asia. The ITS cameras used in these projects contain Pleora GigE connectivity technology and the company also offers a software development kit (SDK) used to program triggers and receive images from the cameras. John Philips, senior product manager at Pleora,
says one important consideration for ITS systems is to ensure all the elements of the system are synchronised in order to capture sharp images of high-speed vehicles. Pleora’s programmable logic controller (PLC),
part of its GigE interface technology, is built into the cameras used in the tolling systems. This allows cameras to tie in the vehicle sensor, the strobe lighting and other cameras through an electrical connection. ‘To capture a rapidly
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