Digital Version of November/December 2014 Print Edition
Vision systems communicate critical information to enforce traffic laws
In an effort to stay ahead of the ever increasing demands of managing and controlling the world’s vast network of roads, the vehicles that use them and the people that rely on them, law enforcement is turning to transportation vision systems for help.
Vision systems don’t sleep, don’t get bored or distracted, and they can remember everything they see, so they can serve as ideal deputies for traffic law enforcement. It is essential that the camera “eyes” for such systems have the right optical performance. In addition, with a few “brains” in the camera, vision systems can provide more capability, communicate information more effectively and simplify installations in traffic applications.
Intelligent traffic/transportation systems (ITS) can provide information ranging from overviews of traffic conditions to details on specific vehicles. Applications include scenarios, such as these:
- A vision system equipped with automatic license plate recognition (ALPR) software can support law enforcement by scanning the highways for specific vehicles;
- To support site security applications, vision systems can be equipped with both license plate and facial recognition software. They can then automatically determine if a vehicle should be granted access through a security gate by checking the license plate and matching it to the driver;
- A line scan camera in the roadbed of a checkpoint can enhance security against terrorist actions with minimal impact on traffic flow by examining the vehicle’s undercarriage as it passes the checkpoint. If the vision system detects anomalies that might indicate the presence of explosives, it can alert guards to take appropriate action.
These various traffic monitoring, law enforcement and access security applications all place slightly different demands on the vision system. Matching the camera to the application’s requirements is essential for obtaining the desired performance at the right cost. Cost is especially critical in applications, such as traffic monitoring, that need many installed cameras in order to be effective.
Cameras for traffic enforcement systems have many requirements in common. The primary need is to capture an automobile image without motion blur, with enough resolution that license plate details are visible, and with a wide enough field of view to provide legal proof of the specific automobile’s presence at a specific location. This legal proof also demands that vision systems provide time-stamping of the images they capture. This information must then be communicated to law enforcement officials to act on it.
Cameras for traffic enforcement also have to be both rugged and reliable. Because they are nearly always in an outdoor environment, they need to be either weatherproof or mounted in a protective enclosure. Further, they should be vibration resistant and able to operate over a wide temperature range. The vision system must also have a long installed lifetime to be cost-effective, so cameras should function for many years with little or no maintenance.
Basic cameras meeting these requirements are already widely used in vision systems for traffic enforcement applications that have relatively simple needs. Toll monitoring, for instance, is typically installed in lane areas that are well-lighted and have restricted vehicle speeds, so image capture is straightforward.
Red-light violation camera systems need higher capture speeds to freeze faster vehicles, but still often have sufficient lighting available. In both applications, there is no need for real-time image processing. The cameras can simply capture images and then communicate this information by sending it to an attached PC for handling.
More advanced cameras with built-in intelligence and networking capability, however, can greatly expand the range of traffic enforcement applications that a vision system can handle. The use of intelligent, networked cameras, such as Teledyne DALSA’s Genie TS series, can thus expand the role of vision systems in transportation law enforcement. Built-in image processing and feature extraction, automated responses to lighting variations and the ability to perform scene analysis for self-triggering of image capture all contribute to system functionality and easier communication of the information gathered. At the same time, these attributes simplify installation, lower data rates and reduce server requirements to reduce such system costs.
Manuel Romero is product manager for Teledyne DALSA’s Genie TS cameras. He can be reached at: