Configuring the License plate recognition RR

To configure the License plate recognition RR detector, do the following:

Go to the Detectors tab.
Below the required camera, click Create… → Category: Vehicle → License plate recognition RR.

By default, the detector is enabled and set to recognize vehicle license plates.

If necessary, you can change the detector parameters. The list of parameters is given in the table:

Parameter	Value	Description
Object features
Check in lists	Yes	The parameter is disabled by default. If you want to use this detector to check in lists of vehicle license plates, select the Yes value (see Checking in lists of LPs)
Check in lists	No
Record objects tracking	Yes	The metadata of the video stream is recorded to the database by default. To disable the parameter, select the No value
Record objects tracking	No
Video stream	Main stream	If the camera supports multistreaming, select the stream for which detection is needed. Selecting a low-quality video stream reduces the load on the server
Video stream	Second stream
Other
Enable	Yes	The detector is enabled by default. To disable the detector, select the No value
Enable	No
Name	License plate recognition RR	Enter the detector name or leave the default name
Decoder mode	Auto	Select a processing resource for decoding video streams. When you select a GPU, a stand-alone graphics card takes priority (when decoding with Nvidia NVDEC chips). If there is no appropriate GPU, the decoding will use the Intel Quick Sync Video technology. Otherwise, CPU resources will be used for decoding
	CPU
	GPU
	HuaweiNPU
Period of ignoring repeated recognitions	0	Specify the period in seconds during which re-recognized license plates will be ignored. The value must be in the range [0, 86400]
Type	License plate recognition RR	Name of the detector type (non-editable field)
Advanced settings
Accuracy and performance	Medium accuracy and high performance	Select vehicle recognition accuracy and performance: Medium accuracy and high performance—provides medium recognition accuracy and high GPU performance (lower GPU load); High accuracy and medium performance—provides maximum recognition accuracy and medium GPU performance (high GPU load)
Accuracy and performance	High accuracy and medium performance
Calibration area height (m)	0	Specify the height of the calibration area in meters. The value must be in the range [0, 500]
Calibration area width (m)	0	Specify the width of the calibration area in meters. The value must be in the range [0, 500]
Frame size change	1920	The analyzed frames are scaled down to a specified resolution (1920 pixels on the longer side) by default. The value must be in the range [640, 10000]. The following algorithm is used: If the longer side of the source image exceeds the value specified in the Frame size change field, it is divided by two. If the resulting resolution falls below the specified value, the algorithm stops, and this resolution will be used further. If the resulting resolution still exceeds the specified value, it is divided by two until it is less than the specified resolution. Note For example, the source image resolution is 20481536, and the specified value is set to 1000. In this case, the source resolution will be halved two times (512384), as after the first division, the number of pixels on the longer side exceeds the specified value (1024 > 1000). If detection is performed on a higher resolution stream and detection errors occur, we recommend reducing the compression.
Initiate event in (sec)	0	Specify the time in seconds after which an event must be generated after recognizing a license plate in the frame. If the value is 0, an event is generated after the track with a license plate is lost. The value must be in the range [1, 3600]
Minimum recognition quality, in %	80	Specify the minimum quality of license plate recognition as a percentage. The higher the minimum recognition quality, the fewer false events. The value must be in the range [0, 100]
GDPR policy	-	By default, on the layout and in the archive, the characters of a license plate are completely hidden "GDPR ON". To display the characters of a license plate, you must enter a value: "-"—hide all characters (default value), " (blank field of a parameter value)"—show all characters, "N-"—hide the first N characters, "-N"—hide the last N characters, where N is the number of characters
Speed detection	Off	Select from the list the mode for determining the speed unit of vehicles. Attention! Margin of error in determining the speed of vehicles is about 5% with a good calibration, as this function gives only a general idea of the situation. The consumption of resources doesn't change when the Speed detection parameter is enabled. Note For the correct display of the speed measurement unit, you must create the MEASUREMENT_UNIT system variable (see Appendix 9. Creating system variable) and specify the value: 0—to display kmph; 1—to display mph.
	Kmph
	Mph
Basic settings
Algorithm for detecting vehicle direction	By LP coordinates	The By LP coordinates algorithm is used by default. It works as follows: if the coordinates of the vehicle license plate shift from top to bottom (the vehicle moves towards the camera) and if the coordinates of the vehicle license plate shift from bottom to top (the vehicle moves away from the camera). Select the By LP scale change parameter if in the Surveillance window, the scale of the vehicle license plate increases (the vehicle moves towards the camera), and if the scale of the vehicle license plate decreases (the vehicle moves away from the camera)
Algorithm for detecting vehicle direction	By LP scale change
Detection mode	CPU	Select a processor for the detector operation (see Selecting Nvidia GPU when configuring detectors) Attention! It can take several minutes to launch the algorithm on Nvidia GPU. You can use caching to speed up future launches (see Optimizing the operation of License plate recognition RR and Vehicle recognition RR on GPU in Windows OS).
	Nvidia GPU 0
	Nvidia GPU 1
	Nvidia GPU 2
	Nvidia GPU 3
Info on unrecognized LPs	Yes	The parameter is disabled by default. If it is necessary to determine all possible information from unrecognized license plates, select the Yes value
Info on unrecognized LPs	No
Vehicle recognition	Yes	The parameter is disabled by default. If you want to search for vehicles in the archive by vehicle make, model, vehicle class, or other specified criteria, select the Yes value (see Search by LPs)
Vehicle recognition	No
Country selection
Country 1 name	Argentina, Armenia, Austria, Azerbaijan, Belarus, Belgium, Brazil, Brunei, Bulgaria, Chile (starting with DetectorPack 3.13), China, Colombia, Croatia, Cyprus, Czechia, Côte d'Ivoire, Denmark, Egypt, Estonia, Finland, France, Georgia, Germany, Greece, Hungary, Indonesia, Ireland, Italy, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Luxembourg, Malaysia, Malta, Mexico, Moldova, Myanmar, Netherlands, Peru, Poland, Portugal, Romania, Russia, Serbia, Slovakia, Slovenia, Spain, Sri Lanka (starting with DetectorPack 3.13), Sweden, Tajikistan, Tunisia (starting with DetectorPack 3.13), Turkmenistan, Ukraine, USA (starting with DetectorPack 3.12), Uzbekistan, Vietnam, Not used	In the corresponding fields, select from the list one or more countries whose license plates you want to recognize
Country 2 name
Country 3 name
Country 4 name
Country 5 name

If necessary, in the preview window, you can set the calibration area or detection area (see Configuring calibration area and detection area).

To save the parameters of the detector, click the Apply button. To cancel the changes, click the Cancel button.

Configuration of the License plate recognition RR is complete. If necessary, you can create and configure the necessary sub-detectors on the basis of the License plate recognition RR (see Standard sub-detectors).

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Documentation for Axxon One 2.0. Documentation for other versions of Axxon One is available too.