Documentation for Axxon Next 4.5.0 - 4.5.10. Documentation for other versions of Axxon Next is available too.

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ANPR works properly if the following camera installation requirements are met (for a list of supported countries, visit the web-site of the recognition module's manufacturer):

  • a camera should be installed in a horizontal position (refer to manufacturer's documentation).

  • character height is at least 15px, stroke width is at least 2px;
  • minimum allowable contrast for uniformly contaminated license plates should be at least 10% (contrasting visibility of characters relative to the background is 25 on a 256-point scale);
  • maximum allowable non-uniform contamination is no more than 12% (the ratio of the contaminated area to the total area of the license plate);
  • the geometric proportions of the image shall not deviate by more than 10% from the real geometric proportions of the license plate.

Note

If you transmit MPEG-4 or H.264 streams over a stable connection, please set GOP length (Group of Pictures), i.e. the number of P- and B-frames between I-frames, to no more than 4–8 frames.

Attention!

the maximum speed of the vehicle shall not exceed 180 km/h.

For stable ANPR operation, make sure that the image of the license plate is not:

  • unequally lit;
  • overexposed;
  • blurred;
  • distorted;
  • interlaced;
  • dirty.

Attention!

Otherwise, recognition accuracy might be compromised.

Some example number plate images that should be recognized fully and properly:

The camera setup is described in detail in the recognition module manufacturer's documentation.

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