The VIT module object settings panel

1

The Zooming checkbox

Set the checkbox

Reduces the frame size while recognizing depending on the Zone width parameter value.

Boolean type

No

Yes – the frame size is reducing while recognizing.

No – the frame size is not reducing while recognizing

default − the license type is determined automatically,

fast (25 fps),

slow (6 fps)

Enables the generation of the NOT DETECTED event for vehicles whose number could not be recognized

Yes − if the license plate is unrecognized, the corresponding event will be generated.
No − if the LP is unrecognized, then such a vehicle will be ignored

VodiCTL_VPW_PLATE_RATIO_TYPE

This parameter sets info on how height reduced or enlarged the incoming image is. 3 options are possible:

1. No distortions.
2. Automatically depending on the image size.
3. User value.

VodiCTL_VPW_IMAGE_THRESHOLD

Base level of image thresholding. By default − 21.

VodiCTL_VPW_IMAGE_BLUR

The parameter for internal use. The recommended value to set is 13.

VodiCTL_VPW_ PLATE_EXTRA_ANGLE_ANALYSE

Enable/disable the angle analysis algorithm of the license plate image.

VodiCTL_VPW_PLATE_STAR_MAX

Maximum unrecognized symbols on the license plate, at which the result will still be considered the result of the recognition of the license plate.

VodiCTL_VPW_PLATE_PROBABILITY_MIN

Minimum percentage of similarity between the recognition result and the corresponding license plate pattern at which this result can be considered the result of the recognition of the license plate. Using this parameter, the results obtained are filtered according to the authenticity.

VodiCTL_VPW_PLATE_FILTER_ROFACTOR

VodiCTL_VPW_PLATE_FILTER_RODROPFACTOR

The license plate filter coefficient by the so-called image density − ratio of white pixels to total pixels (second strategy). The type is unsigned. This coefficient is used for image thresholding and has the optimal values, which are determined by AutoSDK developers using their own test samples. The parameter is considered as a service one, and its value should be set according to the recommendations of technical support specialists.

VodiCTL_VPW_PLATE_FILTER_SYMCOUNT

Enable/disable the simple license plates filter algorithm by the minimum number of recognized symbols on them. If the algorithm is enabled (the value of the parameter is greater than 0), the base search for symbols on the prospective license plate (geometry, proportions) is performed. If less symbols are recognized on the prospective license plate than specified in this parameter, this prospective license plate is not considered a license plate. That is, the value of this parameter is the minimum characters that must be present on the prospective license plate when the basic algorithm is in use.

VodiCTL_VPW_LOG_SETTINGS

Enable/disable logging of all recognition parameters.

VodiCTL_VPW_PLATE_PRECISE_ANALYSE

Enable/disable precise image analysis. It increases the quality of recognition under adverse conditions (for example, if the characteristics/settings of the camera do not fully meet the requirements or in bad weather). It increases the processing time of the frame by 20-30%, depending on its size. Under normal conditions, this parameter does not affect the quality of recognition.

Enable/disable the number recognition dynamics (by default, the dynamics is enabled).

If the value is True, then tracking is enabled, and the number is recognized by the set of frames. If the value is False, then tracking is disabled, and the number is recognized by each frame separately without taking to account the previous ones, and the quality can vary from 0 to 100%.

VodiCTL_VPW_DYNAMIC_OUTPUT_FRAMECOUNT

Number of frames required to display a license plate. The default value is 0. This is necessary, but not sufficient, for the first output of the result. This condition delays displaying from the first moment of recognition of the license plate in dynamics. The setting is designed to improve authenticity of the results, as well as to hide possible false triggerings.

VodiCTL_VPW_DYNAMIC_WITH_DUPLICATE

Enable/disable the periodic output of license plate recognition results.

VodiCTL_VPW_DYNAMIC_OUTPUT_TIMEOUT

The minimum time required to monitor the license plate (in milliseconds) before displaying the recognition result to the user. This parameter can only be used when the “Dynamic” mode is on. In this mode, the trajectory of the vehicle is monitored, and the user does not immediately receive the recognition result of the license plate, but after the time specified for this setting. In this case, the first recognition result will be replaced by the result of higher quality and subsequently displayed to the user. If parameter 0 is set for this value, the user gets the first result of recognizing the detected license plate.  After the time specified in this parameter expires, the monitoring of the trajectory of the license plate continues until it disappears from the frame.

VodiCTL_VPW_DYNAMIC_OUTPUT_PERIOD

Time period (in milliseconds) over which the recognition result is to be displayed to the user. This parameter can be used only if the VodiCTL_VPW_DYNAMIC_WITH_DUPLICATE parameter is set.

VodiCTL_VPW_DYNAMIC_DURATION_WITHOUT_ACCESS

Maximum permissible absence time of the license plate in the monitoring zone (in milliseconds). After this time, the license plate is considered to be lost and is displayed to the user with the set checkbox.

Time interval (in milliseconds) that affects the algorithm for comparing the preliminary recognition results. That is, if the results fall within a given interval and the geometric distance between the numbers is small compared to the numbers size, then it is considered to be the same object.

VodiCTL_VPW_DNN_DEVICES

A list of devices on which the deep neural network (DNN) computations will be performed. The set of available devices is defined in the <Vodi/devType.h> file.

This parameter can also be set via the Windows environment variable: VPW_DNN_DEVICES={comma-separated list of devices}. For example: CPU, GPU, MYRIA.

VodiCTL_VPW_PLATECANDS_METHODS

A variety of methods for obtaining the candidate numbers. Available methods:

• VodiF_VPW_PLATECANDS_BY_MORPH − old method, works by default;
• VodiF_VPW_PLATECANDS_BY_DNN − a new method based on deep neural networks (DNN).

To ensure the operation in the VodiF_VPW_PLATECANDS_BY_DNN mode, it is important to correctly set the minimum size of the number on the image; the larger it is (for example, from 100 pixels or more), the higher the performance will be.

This parameter can also be set via the Windows environment variable: VPW_PLATECANDS_METHODS={number}. For example: 1, 2.

VodiCTL_VPW_ANALYSE_LEVEL

The level of the number analysis. The following levels of analysis are available:

• VodiK_VPW_TEXT_ANALYSE − the found characters will also be recognized at this level. Set by default and performs a full analysis of the number;
• VodiK_VPW_PLATECANDS_ANALYSE − only candidate numbers will be found at this level, that is, the rectangles of their areas;
• VodiK_VPW_SYMCANDS_ANALYSE − the candidate symbols will also be found at this level, that is, the rectangles of their areas.

VodiCTL_VPW_PLATE_ANALYSE_METHODS

A variety of methods for analyzing the candidate numbers. Available methods:

• VodiK_VPW_PLATE_ANALYSE_METHODS_DEFAULT − default method.
• VodiF_VPW_BLURAN, VodiF_VPW_NAN, VodiF_VPW_TMPLAN, VodiF_VPW_DNNAN, VodiF_VPW_OTSUAN.
• VodiF_VPW_DNNAN − a new number analysis method based on deep neural networks (DNN). Disabled by default.

VodiF_VPW_BLURAN | VodiF_VPW_DNNAN | VodiF_VPW_TMPLAN methods provide the highest number of correctly recognized results.

VodiCTL_VPW_PLATE_DNN_FILTER_ENABLE

Enable/disable the candidate numbers filtering by the deep neural network (DNN).

VodiCTL_VPW_TREAT_PLATECAND_AS_PLATE

Enable/disable the ability to consider each candidate as a number. This means that if the analysis of a candidate was unsuccessful for any reason (for example, it was not possible to recognize the number), then such a candidate will not be lost, but will be given as a number, while some of the information will be missing, namely the pis_plate_variantc will be 0.

VPW_RECOGN_OUTSIDE_PLATECAND

This Windows environment variable makes it possible to prohibit the analysis of a number outside the rectangular area (that is, a candidate number) found by the license plate detector. This is an experimental parameter and it may be removed later.

VodiCTL_VPW_SEQUENTIAL_FLUSH_ENABLE

Enable/disable the ability to change the behavior of the VodiprincFlush operation. Without this parameter, the operation waited for the completion of the analysis of all frames, then transferred the results to the dynamics (if enabled), accumulated the dynamics results, performed the flush operation for the dynamics and finally returned the accumulated result.

With this parameter, the operation waits for the completion of the analysis of the earliest frame, then transfers its result to the dynamics (if enabled) and returns its result. Thus, to get all the results that are still being analyzed, it is necessary to sequentially call the VodiprincFlush operation while it returns the >=BoS_OK status.