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License plate recognition is a term often used in security solutions. Touted as a catch-all solution, users quickly find that, like most things security, it can work like a dream or a nightmare, depending on your installer and your budget.
Vishesh Warikoo, country manager for the Indian subcontinent for Arecont Vision, spoke to Hi-Tech Security Solutions to answer a few questions in our quest to learn more about LPR.
What does the average customer – a supermarket, for example – need to install an effective LPR solution?
In retail verticals like supermarkets, the end-user needs to monitor the traffic movement in their parking slots. This is not only to have general surveillance or managing pay and park areas but also to have a time-synchronised incident-based video for any post-incident analysis. And the video is only relevant when it helps in recognition and identification.
LPR solutions came about mainly from a need to develop an independent vehicle recognition solution. The solution generally comprises a camera connected to an LPR software engine. The camera uses illumination (typically infrared or white light) to capture the image of the vehicle plate, then LPR application software analyses the images and identifies the number plate. This data may be used for enforcement, data collection, access control or to keep a time record of the entry or exit for automatic payment calculations.
The LPR system’s significant advantage is that it keeps the image record of the vehicle, which is a great input for any forensic analysis. Any typical LPR solution will require the following:
• Appropriate cameras for the site, mounted at a suitable height to capture the license plate.
• IR solution or white light specific to the illumination level onsite and image quality required by the LPR engine application. It might also need the power source at the site location.
• LPR application with the associated database to record and process the data.
• Infrastructure like servers, workstations and networking equipment to connect various components, host the application and data.
• Workstation and display units for the end-user interface.
Looking at the camera specifically, what are the critical issues in selecting a camera for LPR? Does the user have to have an HD camera?
The camera plays an indispensable role in the whole LPR solution. It should be chosen to satisfy a few norms to have an efficient or most appropriate image for efficient LPR detection. One of the most important keys is to have sufficient pixels on the characters of the license plate. For an LPR application, our recommended pixel density is 196 pixels per meter as a minimum; it is recommended to estimate it at 300 pixels per meter on the target vehicle license plate.
We also need to ensure that the camera is capable enough to generate the required frames every second required by the LPR engine and also depending on the speed of vehicles passing its field of view. Sometimes, the higher the speed, the higher is the frame rate required. The height of the camera and choice of lens play a key role in solution design. Megapixel counts are a very important criterion to obtain the required pixel density on target, but at the same time you need to consider a number of other aspects like the height of the camera, IR sizing and lens design in your camera selection.
What about low-light scenarios? Do you need additional lighting or are low-light cameras sufficient?
LPR applications need good lighting conditions to improve the application’s performance. We recommend specific camera solutions for LPR, which is either our MegaVideo Compact Series or MegaView 2 bullet cameras series. These cameras can offer optimal image quality, required frame rates as well as the ability to handle extremely low light conditions to generate suitable images. We offer integrated IR solutions with our cameras and also they are integrated to third-party external IR solutions. We recommend IR based solutions for more effective performance in a low light environment. The IR illumination should be sufficient enough so that the reflected IR light from the license plate reaches the camera.
What software will an LPR solution require? There are many applications offering LPR, how will a customer know what software actually delivers low false readings and accurate scanning even when vehicles are moving quickly?
The key to a successful implementation is the ability to capture images with sufficient details. Appropriate camera selection is core to any ideal design and all other components are required to be built around that. The following is a checklist to be followed for the selection of subsequent components:
• Installation guidelines need to be followed (height and angle of view from the camera).
• Integration of LPR application with the cameras.
• Functional features as required from the LPR application.
However, it is always recommended to have some sort of speed breaker (like a boom barrier at supermarket parking entrances and exits) where the LPR camera is capturing the license plates. But the key is to check the ability of the camera to capture the image with the required detail at higher frame rates for vehicles moving at higher speed.
What business value/benefits do customers gain from LPR – assuming they are not law enforcement?
Typically LPR is seen as a law enforcement application, however, it offers significant advantages for enterprises in terms of automated identification of vehicles entering and exiting the premises for advanced access control.
• Identification and monitoring of a vehicle of interest as it enters, moves around and exits the premise and enables response if deviation to a planned movement is observed or desired.
• Automated process for entry and exit can be put in place and the process times can be reduced, this can be very useful in enterprises having a high volume of vehicles passing through.
• Parking planning; the high cost of space incentivizes organizations to evolve mechanisms to allocate, manage and charge parking space utilization with integrated solutions.
• As a strategic tool in organizations where LPR can be used to identify end-users and focus some marketing/sales effort onto a specific base.
• A tool to assist in forensic analysis and prevention of incidents like car hijacking and such crimes.
What does Arecont Vision offer the LPR market?
Arecont Vision is a specialized IP megapixel camera manufacturer that offers flexibility in designing the LPR camera solution architecture on pixel density and frame rates to meet specific requirements of the field of view and the target object in the region of interest to have the optimum detection accuracy. Our recommended megapixel cameras deliver an outstanding resolution to capture every detail whether viewing live or recorded/archived video, with the ability to digitally Pan-Tilt-Zoom (PTZ) images. Also, with support of built-in IR illumination (onboard IR LEDs) and also of external IR illuminators, these cameras are capable of capturing video at the required quality level even in extremely low illumination areas.