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Vision-Based Traffic Control Speeds Ahead In Bad Economy
by Winn Hardin, Contributing Editor - AIA Posted 07/06/2010
By January 2010, in the U.S. alone, $75 billion out of $787 billion in economic stimulus funding had been spent to fund road improvement, including bridges, roadway improvements, information systems, and toll systems. In fact, transportation systems from California to Germany have benefited greatly from economic stimulus packages, and some of that money has found its way to machine vision companies through a variety of traffic, speed, and tollbooth surveillance and automated enforcement systems assisted by the GigE Vision standard.
Stimulus Helps Traffic Monitoring
The economic packages in place in Germany, Austria, and Switzerland have led to an increase in [traffic monitoring] applications, especially in speed enforcement,” explains Adrian Wilkinson, International Marketing and Public Relations for VITRONIC (Wiesbaden, Germany and Kentucky, USA). “I wouldn’t say the stimulus funding was a ‘turning point’ for these applications. Police in these European countries are pretty strict and up to date with speed enforcement technology. Mainly, it’s brought the purchases forward. Instead of doing the projects in 2011, and 2012, they’re doing more systems up front. Thanks to its pioneering technology, VITRONIC has been able to capture a large proportion of this new business.” In contrast to most European countries, police departments in the U.S. tend to hire a service provider to install and operate their speed enforcement systems.
One tool that has helped spread the use of machine vision systems for speed, traffic, and tollbooth enforcement is the GigE Vision® standard. Introduced in 2006 by the Automated Imaging Association (AIA), the standard provides an open framework for video transfer and device control over Gigabit Ethernet (GigE) networks.
GigE Vision Simplifies System Design
“The GigE Vision standard has really opened up traffic applications to us,” explains Paul Kozik, Product Marketing Manager at Allied Vision Technologies Canada Inc. (Vancouver, Canada). “With FireWire, we did see some speed enforcement, but very few in tollbooth applications. Now, we’re seeing more GigE Vision used in these applications because of the long reach of the Ethernet – up to 100 m without a repeater or switch – and the network capability of these systems to reduce cabling needs.” Allied Vision Technologies joined the GigE market by purchasing Prosilica in August 2008, who developed the GigE implementation in-house. The breadth of the product line and high performance of the design propelled the group to a leading position in the industry. With the addition of the Manta, low cost GigE Vision family and the GX, dual port high speed/bandwidth offering, Allied Vision Technologies offers the largest selection of GigE Vision cameras on the market.
Pleora Technologies (Ontario, Canada) specializes in GigE Vision connectivity solutions based on its iPORT line of in-camera and standalone video transmitters and eBUS-PureGEV package of high-performance drivers and SDK. “If you picture a toll road entry or exit, a gantry spans the roadway,” explains Pleora’s Senior Product Manager, John Phillips. “There’s not a lot of room to add additional cables inside the gantry, and you also need to consider the impact of running cabling to the processing unit, which is usually located in an enclosure some distance from the gantry.
"In a recent North American tollbooth application that uses cameras built using Pleora’s in-camera solutions, four cameras were installed to capture license plates at a toll road exit. You can see the benefit of being able to connect all four cameras to one Ethernet cable and then run that cable across the entire gantry and then to the processing unit, rather than having to run 4 separate data cables – one from each camera.”
Pleora’s iPORT engines not only provide GigE Vision compliant output from any camera, but also give system designers the capability to do some onboard processing by using Pleora’s IP (intellectual property) core, and interface to external equipment through a soft ‘PLC’(programmable logic controller) on the board. Pleora’s solutions are able to reduce network latency, while expanding the number of video streams carried by a single Cat6 cable. “Traffic applications use our SDK, drivers, and hardware to make sure that data flows with low, consistent latency and nothing is lost,” concludes Pleora’s Phillips. “This is particularly important in applications like the tollbooth, where the vision system receives triggers from outside inputs and must quickly acquire an image when directed.”
Laser Scanning + Machine Vision = Toll $$
VITRONIC’s TollChecker family of vision systems uses a combination of sensing and communication technologies to provide additional features for automated tollbooths and multi-lane free-flow roads. TollChecker uses a 3D scanning LIDAR system to create a 3D model of traffic conditions from a single scanner. These 3D models can locate vehicles from a gantry position, or be placed along side the vehicle to determine the size, shape, number of axels and even roof loads and trailers of each vehicle. This is the ‘detection’ and ‘classification’ part of the system. Next comes identification where the TollChecker uses standard microwave or infrared devices to communicate with vehicle tags located in vehicles so that they do not need to stop to pay a toll. When identification via the tag is not possible, gantry based LIDAR systems use cameras to capture a picture of the license plate for optical character recognition (OCR) processing in the backoffice or for human review. Finally, all the information is combined in a real-time passage report for each vehicle, verifying that vehicle tags for a dual axel vehicle are not located on three-axel vehicles, for instance, or to capture the license plates of vehicles that use the automated lanes, but do not have a vehicle tag. Similar systems can also be used in crowded metropolitan areas that require special stickers to enter town centers, or environmentally sensitive areas.
“Another advantage to the VITRONIC system is the ability to use 4 megapixel cameras to capture license plates rather than higher-resolution, more expensive cameras. Many agencies outside of Europe feel they need a high-resolution camera – similar to the 10 megapixel digital camera they have at home – to capture a good license plate. But when you use 3D LIDAR scanning to determine exactly where the vehicle is as it passes through the tollbooth or speed camera, you can snap an image of the license plate at exactly the right time.”
Italian machine vision traffic monitoring system supplier, Kria, uses yet a third approach: stereovision. Kria’s T-EXPEED uses a pair of Allied Vision Technologies GigE Vision board-level GB1380 cameras along side a color GB2450C board camera. The two monochrome cameras constantly acquire images of the roadway, while search and triangulation algorithms locate vehicles, pedestrians, and any other moving target within the area of interest and extract 3D locations for each pixel making up that object. When a violation occurs, the color camera captures an image of the vehicles license plate.
“In addition to doing speed detection, Kria can also do object tracking, such as detecting vehicles that swerve off the road, or make a left hand turn where they’re not supposed to,” says Allied Vision Technology’s Kozik. “They can track a great many more violations than just speeding, which is their unique offering to the marketplace, plus you don’t have to do specific calibration routines since it uses a 3D approach that can detect buildings, walkways, roads, etc. Many of these systems are being installed on the top of police cars, which give the police a mobile system with greater flexibility than a fixed system.”
VITRONIC has recently offered a mobile version of its PoliScanspeed LIDAR/machine vision speed enforcement system that can easily be moved to any location during the day, and then slid back into a permanent enclosure for monitoring a specific location at night (or vice versa). Other improvements include the growing use of wireless LAN technology so that agencies can avoid the expense of connecting the traffic monitoring system to a wired data network, while reducing data collection times. VITRONIC, for instance, also offers systems with removable hard drives, but does not recommend these systems for high-speed roadways where collecting the drive could put public safety personnel in harm’s way. The whole point of VITRONIC’s traffic enforcement systems is to create safer roads…..for everyone.
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