In order to get the good quality picture for license plate recognition,we need to pay attention to the following requiremnet:
Installation Environment
Before the installation, do as follows to ensure that the environment meets the installation requirements:
1.Illumination:
The ambient illumination must range from 70 lux to 900 lux. When the light intensity is insufficient, consider to use illuminators to supplement light.
Avoid direct exposure to a strong light. After the installation is complete, the camera lens should not be directly exposed to a strong light (such as sunlight, street lamps, or vehicle headlights).
Avoid light reflection. Keep the camera away from highly reflective objects such as glasses, ceramic tiles, and waters.
2.Direction of light:
The light is irradiated evenly. Uneven light will cast shadows on license plates.
Try to avoid front light or backlight. For example, a camera facing the east or west may produce too dark or overexposed license plate images at sunrise or sunset.
3.Others:
Avoid low-color-temperature light sources (such as a sodium lamp) within the camera's field of view. At night, the color effect of the sodium lamp may affect the license plate recognition and vehicle color recognition.
Try to avoid large-sized tree or building shade in the capture area. In the shade, the captured vehicle or license plate image may appear too dark.
Installation Location
The camera location affects the accuracy of license plate recognition. You are advised to select locations based on the following rules:
The path that is within 50 meters in the front of a camera must be a straight line, and the camera must directly face the front or back of the vehicles.
The camera must be installed about 0.5-1.5 meters away from the roadside or above the center of the road.
Installation Height and Distance
Micro checkpoint cameras must be installed at a height of 4.5 m to 6 m. If the installation height is lower than 4.5 m or higher than 6 m, the accuracy of license plate capture and recognition will be affected.
The horizontal installation distance (D) must range from 15 m to 25 m. Distance D may be three to four times the installation height H.
The length L of the capture and recognition area must range from 15 meters to 20 meters
