Understanding License Plate Camera Rhetoric
The Automated License Plate Recognition (ALPR) or Automated Number Plate Recognition (ANPR) refers to a security camera that has been around since the early 1980s to identify vehicles by the license plate. The ALPR is used primarily in North America, where the ANPR designation is found in Europe and European influenced countries. The first commercial cameras were large analog box cameras mounted at tag level with a special filter to capture the raised tag numbers. Today, ALPR cameras are much smaller, with optimal mounting height of 12’ on a pole, consisting of one or two cameras with infrared illuminators (IR), both internal and / or external to help build tag definition. While traditionally the ALPR camera has been deployed by Public Safety both in fixed and mobile applications; ALPR cameras have become common in commercial and B2B applications.
Best Practices for Fixed Installations For accurate tag recognition ALPR camera should be mounted at 12’ with a focal point based on the camera lens or camera zoom ability. The camera should be mounted to focus on one lane at a time. While many offer a focal length and lens aperture to capture multiple lanes, the compute in the camera needed to “see” multiple cars and even to send the images is more than most cameras. If the camera is running an onboard analytic, this compute will be battered even more. The camera should have the ability to capture tags at 30MPH higher than the expected vehicle speed.
While not every scenario can offer best practices, it is best to design with these in mind.
Best Practices for Mobile Applications Mobile applications have many variables, but should have good connectivity and compute internally to process images quickly and accurately. Mobile applications can use magnetic mounts for temporary applications or can be bolted to the vehicle for permanent installations. Ensure all penetrations are sealed appropriately. Most mobile applications will be performed by the manufacturer or a factory trained representative.
LPC or LPR? Today there are two types of ALPR cameras. License Plate Capture (LPC) and License Plate Recognition (LPR). The LPC camera requires enough megapixels (MP) to be able to zoom to get an accurate “read” of the plate. All LPCs are an IP Camera designed to run Optical Character Recognition (OCR) analytic. The LPC is limited as it requires a manual input of license tags, and a manual review for a match. The LPR camera is a camera or analytic designed for “recognition” and automation / integration of the recognition software to provide immediate “hits” via a traditional video management system (VMS) or a connection to cloud shared or government repositories. The confusing area here is that some LPR cameras can be IP cameras running OCR analytics. The robustness of the analytic becomes a larger deciding factor. Both offer distinct values depending on the use case. For either option, depending on type and installation, costs can range from $2000.00 to $50,000.00 or more for a single camera installation. Decisions for integration into 3rd party platforms such as parking software, B2B connections, or Public Safety should be identified during the design phase as this can determine which type of camera is specified.
The IP Camera with OCR analytics The traditional IP camera with OCR analytics is a color sensor camera surrounded by a ring of infrared (IR) illuminators of one wavelength, typically around 850nm. For the purposes of ALPR the camera manufacturer typically includes a way to upload a whitelist (approved) or blacklist (alert) on the camera. Whitelist tags can be utilized for access control, while blacklist tags create an alarm either local to the camera or if it is integrated to a VMS or recording platform it will alert the user. One advantage of the IP camera is that it is a color sensor camera that can be used as any other security camera, not limited to a single function.
Many camera manufacturers have now made a LPC camera FOR OCR analytics, but the analytics do not come installed. A separate analytic package must be purchased. Some of the IP cameras have the ability to run the analytic on the camera, others require and edge device to be collocated with the device or run on an analytics server at the head end. These additional hardware and software applications will affect the installation cost. The analytics packages can have integration with Point of Sale systems for Pay to Park scenarios. Depending on the manufacturer or Integrator, the LPC can be purchased upfront or as a subscription plan. With the traditional IP camera solution, the buyer needs to know its Advantages and Limitations.
Best Use Cases
Pay to Park with camera in fixed location with good ambient light.
Neighborhood entrances with good lighting.
Vehicle recognition for member loyalty programs.
Access Control for residential parking decks.
The ALPR camera The traditional ALPR camera is a camera housing with one or two camera sensors. If one sensor, the sensor will be a black and white camera with a fixed focal length. This focal length will be determined prior to ordering and will be set and calibrated prior to shipping. If the unit has two sensors, the second camera will be a small color camera for context views while aiming the black and white camera. The camera may be an IP camera, but it may have proprietary cabling to a collocated power supply / network device. These devices typically have multiple wavelengths of IR illuminators, ranging from 710nm to 950nm for ranged recognition of tags. Like the IP camera, these cameras have multiple whitelist and blacklist databases onboard. The cameras may have a version of Windows or Linux imbedded on the camera itself. The ALPR camera has a way to record tag matches onboard if disconnected, and once connected to upload all tag data to a recording platform. The recording platform may be a pay to park software, a VMS (either on-premise or cloud hosted), shared repository, or government repository. A shared repository would be a cloud hosted option that allows multiple vendors to match recognitions to other vendors. This works well where tow truck drivers get “hits” from other ALPR camera locations. Two types of government repositories are the National Crime Information Center (NCIC) hotlist and the Drug Enforcement Agency’s High Intensity Drug Trafficking Area (HIDTA) hotlist. These hotlists are privy only to public safety. Each department must apply for access and will be provided a time of day when their server will access the list. This access will occur twice a day for each department. Most LPR cameras will be set up from the factory to use a cellular connection. Each LPR camera location will be set up as a stand-alone location transmitting back to a central repository. Each additional camera at the site will be added to the location; each new location will be a separate stand-alone application with new hardware and hardware costs.
With the traditional ALPR camera solution, the buyer needs to know its Advantages and Limitations.
Best Use Cases
B2B Offerings (Tow Companies)
City / Campus Parking Solutions
Public Safety applications
Locations where higher speeds are being used
Public Private Partnership (P3s) to include businesses and neighborhoods
Mobile ALPR Cameras Unlike the LPC cameras, most LPR camera manufacturers have created a version of the LPR camera that can be mounted on a vehicle. The Mobile cameras may still have the proprietary cabling, but will have a power supply mounted inside the vehicle. Like the fixed LPR camera, the mobile version is ready to use a cellular connection either dedicated or as part of the vehicle infrastructure. Mobile LPRs can be found on public safety vehicles, tow trucks, parking services vehicles, trailer drawn applications, and covert applications.
Public-Private Partnerships (P3s) and B2B applications The ALPR camera is a great way for neighborhoods, businesses, and B2B applications to benefit from tag recognition data. P3s and B2B applications provide faster responses to automated “hits” while eliminating worry and the need for anonymity.
The Future Is… License Plate Capture and License Plate Recognition technology has been around for many years, but with the introduction of the Internet of Things (IoT) and the IT / IoT / OT convergence, the ALPR camera is being developed and sold to meet new and unique customer needs. As the ALPR technology grows, gains accuracy, and prices drop; more businesses and neighborhoods will begin to utilize this technology as ways to offer access control, revenue generation, and overall safety.