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How to set up License Plate Recognition (ANPR, LPR, NPR, ALPR) - TrafficSurvey
How to set up License Plate Recognition (ANPR, LPR, NPR, ALPR) - TrafficSurvey

If you are able to read the license plate, our AI can do it too!

Marta avatar
Written by Marta
Updated over a year ago

License Plate recognition is an image analysis with optional use, not activated, and run at default configuration of DataFromSky. It can be activated at any time within the settings of the given video or while uploading new image data. When the function is activated, a special image recognizer for number plate reading for vehicles with a suitable angle is run alongside the standard deep traffic analysis. If there is a reliable number plate detection, it is stored as one of the attributes of the vehicle’s trajectory (similarly as the vehicle’s category or color).

Safety and privacy are on top for us

We are aware that the license plate numbers are sensitive data that in many cases cannot be collected and further analyzed even though information about the behavior of a particular object is key for research purposes. DataFromSky offers a simple solution for such cases. Using the hash function, we convert the detected number plate to another numeric value that is not reversible but unique to each object. Your data will still contain information about the behavior of the object, but will no longer include sensitive information. When ordering number plate detection, you can choose to save the data as a hash (default) or as a plain text. We care about security and privacy!

Which countries are supported?

TrafficSurvey can detect all EU license plates as well as most alphanumerical-only license plates. See the image below for examples of license plates that the TrafficSurvey LPR service can read. Please note that in order to read a license plate reliably, it should be at least 18pixels in the vertical dimension but this is easily achieved for most videos. You can also test whether license plates will be read in your video for FREE by ticking the LPR option when doing the 5-minute free sample analysis (max 10x samples per 24hours).

98% and higher reliability

Thanks to a combination of deep traffic analysis with number plate recognizer, the outputs of the function are extremely accurate. Number plate detection is run only at vehicles recorded with a suitable angle. Based on tracking of the vehicle’s trajectory, the final output is continuously made more accurate via the aggregation of the partial outputs. This method ensures almost total elimination of false-positive detections, which are rather common at other traffic analysis tools (e.g. number plate detection at road signs, vehicle pasting, etc.). Moreover, the number plate recognizer optimizes itself for the concrete video, making the whole process even more accurate. You can try the number plate detection tool functionality by opening the sample analysis, which is free of charge, within the Viewer application. The outputs will be visible directly within the analyzed video.

DataFromSky is able to re-identify the vehicle from two different places.

Filtration by direction or time, number plate exporting

As the detected number plate (or hash) is an additional attribute to the vehicle’s trajectory, spatial, time, and even attribute filters can be easily applied to it within the DataFromSky Viewer application. Therefore, it is not a problem to acquire a list of number plates (or hashes) or even a group of vehicles in a certain direction, or of a certain category, and use only one export function for the whole data export. The vehicle’s number plate (or hash) is then one of the attributes within the generated CSV file, which can be easily used and processed in any third-party application.

Export with plain license plates.

Export with hashed license plates.

How to make a suitable video for License Plate recognition?

As number plates are not practically visible from the bird’s eye view, the number plate detection function is available only within the LIGHT version of DataFromSky. However, even in the case of using fixed cameras, there are certain rules to ensure extremely high reliability of the number plate detection, including:

  • The minimum size of an object or a sign within the image must be at least 18 pixels

  • Use High-quality video output (FullHD or 4K)

  • Number plates must not be blurred and must be easily readable and visible to the naked eye

  • Number plates must not be overexposed (with too much light) or underexposed

  • Number plates must not be deformed (for example by interleaving or by the rolling shutter effect)

We will be happy to answer any questions you may have. Contact us!

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