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4.6 Example of input/output monitoring
The following drawing shows a typical example of input/output monitoring
Distance from vehicle: 6 metres
Installation height: 1.6–2.0 metres
Lateral deflection: Approx. 1.5–2.0 metres
If the ANPR camera is installed at a height lower than 1.6 metres, recognition of the
number plate is still possible, however the risk of direct sunlight impairing the video
image is increased. This can lead to a decrease of the recognition rate.
A lower installation height of the ANPR camera also makes it possible for the
distance between the barrier and the vehicle to be less than 6 metres. However,
there is still the risk of direct sunlight interfering with the video image.
4.7 Setting the exposure time of the camera
Especially with moving vehicles, the exposure time plays a major role. By default, it is set to 1/25
or 1/50.
The faster the vehicles pass the camera, the shorter the exposure time must be set. Otherwise a
sharp image of the number plate is not possible and the identification may contain errors.
A value for the exposure time of 1/200 or 1/400 should be selected.
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