Video camera requirements for the Traffic violations detection

1

Camera type

CCTV

High resolution digital cameras can also be used.
IP-cameras have not been tested.

2

Camera resolution

Not less than 520 TVL horizontally.

Only high resolution CCTV camera usage guarantees the recognition rate declared in the technical characteristics of the system.

3

Illuminance of the monitored area

Not less than 50 lux for cameras with 0.05 lux CCD sensitivity;
Not less than 20 lux for cameras with 0.0002 lux CCD sensitivity;
0 lux for cameras with IR illumination.

At night time, standard auto road illumination devices are sufficient to provide 50 lux illuminance in full compliance with the building regulations.

4

Automatic amplification adjustment

LOW or MIDDLE depending on the camera

This function must be enabled. Unfortunately, the scene is usually not sufficiently illuminated, thus the image looks too dark in case this function is disabled. Enabling this function amplifies the whole video signal including the CCD noise. The amplification value is chosen for each camera separately.

5

Auto aperture and auto electronic shutter

• not more than 1/500 sec for vehicle speed below 40 km/h;
• not more than 1/1000 sec for fast motions (vehicle speed above 40 km/h).

The image should be sharp. Sharpness can be achieved by locking the shutter speed (exposure). Locking the speed of the electronic shutter is a very important function.
When the exposure is long, i.e. the shutter speed is low (1/100, 1/50 sec), the moving objects are blurred in the image. This most affects the small details, eg. the symbols in license plate numbers. The video sequence as a whole may look good enough, but the static frames that comprise it may be blurred, making LP number recognition partially or completely impossible. If the camera is not forced to operate at high shutter speed, it will automatically switch to long exposure in case of poor lighting conditions, preventing plates recognition. With the same settings, the camera can recognize the numbers in bright light only, automatically switching to short exposure.
If the camera is installed at an angle more than 10 degrees to perpendicular to the license plate, we recommend to halve the shutter speed.

6

Color

Black and white image

No color camera is required for recognition of even colored license plates. Black and white cameras are recommended due to higher resolution and sensitivity compared to color cameras.
Color cameras can be used if color images need to be saved only. In case of color camera usage, be sure to provide enough scene illumination at night time.