1. Installation Instructions
1.1 Installation Location
The camera must be installed behind the barrier and facing the vehicle, as shown in the image
And the distance between the camera and the barrier cannot be too great; the shorter, the better.
1.2 Installation Height
The suitable installation height for the camera is between 1.6 m and 2 m
1.3 Depression Angle
The camera's depression angle must be less than 30 degrees; that is, the angle between the camera and the horizontal line >25 degrees
1.4 Adjusting the Camera's Rotation Angle
It is essential to make every effort to adjust the camera's rotation angle to ensure that the license plate is parallel to the horizontal line. In addition, the deviation must be less than 5 degrees if the vehicle's license plate is not horizontal under certain conditions.
The software requires this type of setting; the smaller the deviation, the better the license plate recognition will be.
We are providing the link to the article where we have attached a file that serves as an installation distance calculator for LPR cameras:
2. Configuration Instructions
The camera settings can mainly be divided into three parts:
- Camera image settings.
- Detection settings.
- License plate list management.
2.1 Camera Image Settings.
To achieve correct license plate reading, it is important to adjust the camera's image parameters according to the installation conditions, especially the speed of the vehicles and the available lighting.
It should be noted that these settings may vary depending on the camera model, and a configuration that is valid during the day may not provide the same results at night.
2.2 Exposure Settings
To configure the exposure, we will access the camera through its IP address using a web browser and enter this section.
Exposure determines the amount of light the sensor receives to generate the image. Excessive exposure may cause license plates to appear overexposed, while insufficient exposure may make the characters appear too dark.
One of the main parameters we need to adjust is the exposure time.
Exposure Time (Shutter)
Exposure time indicates how long the sensor captures light.
- Short exposure time: allows sharper images of license plates from moving vehicles, although the image will be darker.
- Long exposure time: allows more light to be captured, but may cause license plates to appear blurry when the vehicle is moving.
Therefore, the higher the vehicle's speed, the shorter the exposure time should be.
Hikvision establishes the following recommended values for certain LPR camera series:
| Vehicle speed | Exposure time |
|---|---|
| Less than 30 km/h | 1/150 – 1/200 |
| Between 30 and 60 km/h | 1/250 – 1/500 |
| More than 60 km/h | 1/500 – 1/1000 |
These values must be adapted to the lighting conditions and the installation.
2.3 Gain (Auto Iris)
Gain increases image brightness by amplifying the sensor signal.
However, a value that is too high may introduce noise and reduce character definition.
For certain LPR series, Hikvision recommends using a gain value of 20 as an initial reference.
It is recommended to adjust the exposure time first and then check whether it is necessary to modify the gain or the camera's lighting.
2.4 WDR Configuration
WDR (Wide Dynamic Range) compensates for lighting differences between the bright and dark areas of an image.
This function can be useful in installations with significant backlighting, such as garage entrances or areas where sunlight shines directly onto the camera.
However, for LPR cameras, it is recommended to initially keep WDR disabled, as its processing may cause ghosting or loss of sharpness in license plates of moving vehicles.
For this reason, before enabling WDR, it is recommended to try to correct lighting problems through the exposure and gain settings.
WDR settings can be found in this section:
IMPORTANT: In an LPR camera, we must prioritize ensuring that license plate characters are legible, even if this means that the rest of the image appears darker, especially at night.
2.5 Detection Configuration.
After configuring the camera image, we must enable vehicle detection in the camera's VCA section.
Next, we access the vehicle traffic section to configure detection.
Next, we will enable detection and configure the detection parameters.
We will need to take into account the number of lanes to be detected and adjust the lane boundaries and the detection line.
We will also need to take into account the region of the license plates to be detected.
Afterward, we must adjust the operating schedule in relation to the license plate lists and how they will operate after the license plates are compared.
You must take into account the operating schedule and the actions to be performed, whether this is an email notification, a notification to the notification center (mobile app and desktop environments), and whether this will open the alarm output to open barriers or perform a similar action.
Using the upload via FTP option, license plates that match the rule will be stored on the camera's MicroSD card.
2.6 License Plate List Management.
Next, we will begin adding the license plates to the camera's database. You must access this section:
In this section, we enter the license plate itself and choose which list it will be included in. We will also indicate the period of validity the license plate will have in the system by setting a start and end date.
If you wish to import a complete list of license plates, we recommend adding one manually and exporting the camera's XLS file. This way, the format used by the camera will be respected.
Once you have completed that template, you can import the license plate list directly into the camera.
3. License Plate Search.
3.1 Searching for License Plates from the Web Interface
To search for license plates stored on the camera's MicroSD card, you must access the camera's playback section. Within it, we will select the image section.
After expanding this section, the available filters will be displayed, where we will select vehicle detection or mixed traffic, depending on the previous detection configuration.
We can also search for a specific license plate and filter by the detection date and time.
In the right sidebar, we will find the license plates stored according to the configured detection and matching.
3.2 Searching for License Plates from IVMS4200
To perform searches from IVMS4200, you must access the Data Retrieval section.
After accessing this section, you must select the AcuSearch option, where you will find the Vehicle Retrieval section. Within this section, you can select the camera and apply filters to find the license plates stored on the camera's MicroSD card.