Overview

What is ALPR?
The automatic license plate recognition (ALPR) is a technology based on artificial intelligence that reads the license plate numbers of the vehicles appearing in the captured images.

The deep learning AI based ALPR is capable of reading license plates from various angles and even when the vehicles are moving fast. For example, the camera may be installed above the traffic tilting downwards, or on the roadside looking sideways.

Camera Requirements
The cameras that are used for capturing clear ALPR-readable images have very good low light sensitivity so that they can maintain very high shutter speed to reduce motion blur while still capturing enough light to make the image clearly visible.

Those cameras also need to have a very good WDR, because they have to be able to read the front side license plates regardless of the interference from the headlights of the vehicle.

It is also important to have a high frame rate capability so that multiple images could be captures within that short moment while the vehicle is in the view of the camera. This way, there are more choices for the most ideal snapshot for the analysis.

Furthermore, it is important to decide how many concurrent lanes of traffic would one camera have to manage. Some cameras can manage 2 or even 3 lanes at the same time.

Camera or Server ALPR?
Once the clear image is captured, it will be forwarded to the ALPR analysis. It can be done either inside the camera directly, or by the remote AI server.

There are many benefits of having ALPR analysis done inside the camera directly - the faster response time, distributed computing power, and no AI license required. ACTi's solution is to use camera-based ALPR as the better choice.

Metadata Collection or Alert?
There are two main ways to handle the captured license plate information. One is to simply collect and pass forward to the management server, such as VMS. This way the camera does not need to make a decision about which license plates require special attention. The server collects metadata and stores it for the later search purposes.

Another way is to maintain a specific database inside the camera directly - as a whitelist or blacklist. The whitelist is used to manage the permitted visitors whereas the blacklist is mostly used for wanted vehicles by the law enforcement.

When the license plate is captured and the camera compares the result immediately with its database of license plates of interest. When the match is found, the camera alerts the VMS immediately. The VMS can be configured to take various actions automatically when such event comes in, such as producing audio alarm, popping up instant video from that specific video channel and more. The alert-based solution means that normally the VMS does not collect the metadata about the unrelated license plates and only receives license plate data from the camera upon the events.

Applications

ACTi ALPR cameras are designed for various applications, such as highways monitoring, city surveillance, and parking management.

Features

• Various ALPR camera types - zoom bullet and PTZ
• Resolution up to 9MP
• Optical Zoom up to 60x
• Frame rate up to 120fps under 2MP mode
• Capturing vehicles moving up to 320 km/h Front and side installations
• ALPR recognition distance ranging from 4.5 to 900 meters
• Monitor up to 3 lanes simultaneously

Solutions

ACTi's ALPR solution consists of ALPR cameras and NVR. There is a wide range of camera options to choose from.
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We recommend using ACTi's NVR 3 Corporate as the main management server of receiving either ALPR metadata or events from the camera. There is no AI license required. The regular video channel license is applied.
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