High Intensity Infrared Illuminators in ANPRs, Transportation Security and Biometric Facial Recognition|
Article - May 15, 2017 By LarsonElectronics.com
High Intensity Infrared Illuminators in ANPRs, Transportation Security and Biometric Facial Recognition
Automatic number plate recognition (ANPR) has evolved greatly in the past decade. This technology is being used by numerous businesses and government organizations. Law enforcement groups rely on such systems to capture individuals speeding at intersections, via traffic light cameras. Electronic tollway systems also use ANPRs to improve the success rate of real-time detection during collections.
The main components of ANPRs include the following: cameras, high intensity infrared illuminators and software algorithms used for analysis and detection. This article focuses on the critical role that infrared illuminators play in supporting monochrome cameras, improving transportation security and streamlining biometric facial recognition accuracy.
Patent US7016518 B2
The nascent application of high-power infrared illuminator can be traced back to a 2002 patent titled ‘Vehicle license plate imaging and reading system for day and night’ (US7016518 B2). The patent indicates that an infrared illuminator may be used to increase the range of capture at night or during dark conditions, when the cars are moving quickly, as well as when headlights are operational. The image captured by the monochrome camera undergoes manual processing by an operator, who converts it into text format using “optical character recognition computer hardware and software.” The data is then processed and used for verification at the gate. This process happens very quickly; and in order to improve accuracy, the infrared illuminator must be reliable and powerful.
The authors suggest that the infrared illuminator must be capable of reaching distances up to 115 feet (approximately 35 meters). Furthermore, the wavelengths should range between 830 and 1,000 nanometers. To maintain this range, an optical filter is applied, which cuts wavelengths outside of this preferred range (below and above). A weather-tight housing is also recommended to streamline functionality in rough weather conditions.
Transportation Monitoring/Security Applications
Infrared illuminators may also be applied to improve vehicle counting and vehicle classification (axle) processes. This data is used by transportation authorities, pavement designers and government organizations to monitor traffic, conduct surveys and compile statistical reports. Interestingly, researchers at University of Pune (India) have created a reliable method for vehicle axle counting, using infrared LED pulses. For such applications, an infrared LED light with a wavelength of 940 nanometers is used to illuminate an area of 8.2 feet (2.5 meters).
Outside of vehicle counting, transportation authorities are using infrared light to monitor suspicious activity on roads. For example, monitoring systems that utilize infrared illuminators, cameras and computer recognition are being applied to detect solo drivers attempting to take advantage of express lanes designed for high occupancy vehicles. In the same domain of applications, such systems may be used to monitor criminal activity at unsupervised rest areas and neighborhood intersections.
Infrared Light and Biometric Facial Recognition
Establishments and buildings that require high security, such as government facilities, laboratories, private parking lots and power plants, all rely on some form of verification or screening before entering the premises. Most use access cards and fingerprint authentication, which come with several disadvantages. Cards can easily be lost, stolen and replicated. Fingerprint authentication requires numerous steps and the pad must always be clean and properly maintained.
Biometric facial recognition is the next step in reliable authentication and screening. The process works by mapping out one’s facial features using infrared light. Lighting manufacturers have already started to supply this need, via the use of extremely compact 3030 and 3535 LED chips. The application of these infrared LEDs allows biometric facial recognition systems to work accurately.