Image taken during the night by Safe-T-Cam showing a truck and its licence plate.

Safe-T-Cam: keeping an eye on the road

CSIRO-developed automated imaging technology has found multiple applications helping traffic authorities monitor vehicles on our roads.

  • 14 January 2008 | Updated 14 October 2011

Overview

CSIRO, in collaboration with the NSW Roads and Traffic Authority (RTA) and telecommunications company Telstra, developed Safe-T-Cam – a world-leading technology aimed at improving road safety by monitoring transport.

Safe-T-Cam uses generic technology with broad applications in the vehicle operating and traffic law enforcement industry.

The system combines infra-red technology and high-resolution cameras to capture images of passing vehicles.

The digital image is analysed using computer recognition software, which deciphers the vehicle's licence plate.

Safe-T-Cam has been used by the RTA to monitor:

  • speeding
  • unusual driving behaviour
  • vehicle registration.

Other proposed uses include monitoring by the operators of:

  • toll roads
  • car parks
  • weigh-in-motion inspection stations for truck and bus fleets
  • port and customs authorities for cargo container security.

Technology

The technology involves two stages of image capture, first by video, then by high-resolution still shots.

The video camera images at a rate of fifty fields per second and passes this sequence to the CSIRO-developed image processor called HYMOD (Hybrid Modular Processor). HYMOD performs several image processing tasks to separate the moving vehicles in the images from the background regions.

Incoming Safe-T-Cam video image of truck on road

Incoming video image

Background Safe-T-Cam video image of road only

Background image

Differential image of incoming and background images

Difference image

 
Shadow regions marked in green on differential image

Shadow regions marked in green

 
Output binary image with shadows removed

Output binary image, shadows removed

 

An automated process discards ‘blobs’ that are either not associated with a vehicle, or multiple vehicles merged together.

Vehicles are then labeled according to size and tracked through the video sequence.

When one of these vehicles crosses a particular part of the video image (the trigger point), a high-resolution image is taken using a stills camera. There is one high-resolution camera per lane of traffic.

The image is stored on computer and passed to an Optical Character Recognition module that reads the licence plate details. 

Currently, there are 22 Safe-T-Cam sites in operation throughout New South Wales.

This data is then passed to the central site via a communications link. The central site can use this information to monitor vehicle movements across the Safe-T-Cam network, or perform other tasks such as registration checks.

Currently, there are 22 Safe-T-Cam sites in operation throughout New South Wales.

Enhancements

The system has been updated to facilitate the use of a thermal camera. This overcomes problems associated with processing video images from a standard camera such as:

  • applying different algorithms for day and night sequences
  • dealing with shadows from vehicles and objects adjacent to the roadway (such as trees, bridges)
  • capturing vehicles at night which try to avoid detection by switching their lights off.

 
Standard video camera image taken during the day showing a car overtaking a truck on a road.

Day time, standard video camera

 
Safe-T-Cam image from thermal camera taken during the day showing a car overtaking a truck on a road.

Comparative day time, image from a thermal camera.

 
Standard video camera image taken during the night showing a car overtaking a truck on a road – only the lights of each vehicle can be seen.

Night time, standard video camera.

 
Safe-T-Cam image from thermal camera taken during the night showing a car overtaking a truck on a road – the vehicles can be clearly viewed.

Comparative night time, image from a thermal camera.

CSIRO-developed software can recognise a variable number of characters on license plates and is insensitive to logos and decorative emblems. It also performs contrast enhancement on the image where the contrast is low. The recognition rate is 80 per cent.

Awards

The Safe-T-Cam technology has won the following industry awards:

  • Honda Award for Best Technology Presentation at ISATA, an international engineering conference, Aachen, Germany, 1994
  • Rolls Royce/Qantas Award for Engineering Excellence, Sydney, 1995.

Find out more about CSIRO's work in Sensing & Sensor NetworksSensing & Sensor NetworksSensing & Sensor Networks.