INTELLIGENT TRANSPORT
Vision in lane
Jessica Rowbury looks at the latest vision technology for ITS, including a system for monitoring six lanes of traffic
A
t Intertraffic China 2015, which took place 31 March to 2 April in Shanghai, companies demonstrated
that monitoring the road is much more than just measuring speed. Modern imaging solutions stretch far beyond traditional traffic applications; developments in resolution, speed and processing power have allowed vision manufacturers to design smarter, smaller, and cheaper systems with significantly increased capabilities. Current intelligent transport systems (ITS)
are capable of monitoring multiple high-speed events simultaneously, serving as an all-in-one solution for traffic authorities. Launched at the Vision show last year, the T-Exspeed intelligent transport system from Italian company Kria can measure a range of different factors across six lanes simultaneously. ‘Any vehicle trajectory or every visible feature on the vehicles can be automatically recognised and stored,’ said Stefano Arrighetti, CEO of Kria. ‘For example, the device already detects wrong way, change of lane, tailgating, forbidden turns and so on. It recognises license plates, dangerous goods placards, vehicle colours and classifies vehicles on the base of their 3D sizes.’ And, because the system was designed as
an open architecture, it is possible to add new functions aſter installation. ‘Very oſten we
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develop “on demand” customised functions that we could not even foresee when the device was sold and installed on the road,’ explained Arrighetti, adding that since its launch, the soſtware has been upgraded to include functions such as detecting vehicles that fail to stop at intersections and a link to the national black list database, among others. To monitor six lanes simultaneously, the
challenge is to keep up with processing the huge amount of uncompressed data from the stereo cameras, Arrighetti remarked. ‘We have to quickly locate vehicles inside the camera field of view. Aſter doing so, an important challenge is to be able to simultaneously track in parallel multiple moving targets. Sometime within the six lanes there are more than 10 vehicles at the same time,’ he said. At a higher processing level, another
important aspect is to measure speed with the highest possible accuracy. ‘To do this, sub- pixel algorithms are necessary because even a fraction of a pixel makes the difference. In terms of computational effort, this is like using sensors with higher than their nominal resolution,’ Kria added. Te capability to monitor six lanes at a
time took years of development, according to Kria. Te system introduced in 2014 employs Prosilica GT4907 and GT6600 cameras from
Allied Vision, which have 16 and 29 megapixel resolution respectively, and full frame sensors. Kria’s first multi-lane system was designed in
2008, capable of observing two lanes at a time. It contained a 1.4 megapixel Prosilica GC1360 camera. ‘It was a stereo device with 100cm baseline, able to monitor two parallel lanes with one per cent speed error. Te long baseline was needed to achieve the desired accuracy,’ Arrighetti said. In order to increase the capability and
measure three parallel lanes, the company released another version of the system in 2010, which featured a 5 megapixel camera and a reduced 66cm stereo baseline. For the third and current version of the
system that was launched at the Vision show, Kria’s engineers managed cut the stereo baseline down to 29cm while keeping the speed accuracy fixed at one per cent. To improve the instrument’s capability while
maintaining the same level of accuracy proved a huge challenge, especially as the distance of vehicles in the camera field-of-view increases in proportion to the number of lanes. ‘To keep the same three-dimensional measurement accuracy we would also increase the stereo baseline proportionally. But Kria’s R&D challenge was that we could neither increase nor keep the same baseline,’ commented Arrighetti. Another difficulty was to scale down the
technology in order to make the device mobile without compromising performance. ‘To make the device actually portable and to install it
April/May 2015 • Imaging and Machine Vision Europe 19
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