Number plate recognition detects and reads license plates on vehicles.
This section describes the parameters that you can use to configure number plate recognition.
Configuration Parameter | Description |
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Boldness | The boldness setting to use for detecting the edges of characters. |
ExpectedRotation | The expected amount of rotation (from horizontal, in degrees) for a number plate in the scene. |
FormatsFile | The name of the format file to use to read number plates. |
FrameRate | The number of frames to analyze per second of video. |
FreeformRegion | The Region of Interest (ROI) to monitor for number plates, if the ROI is not rectangular. |
Input | The image track to process. |
Integration | The method to use to integrate multiple number plate reads into a single result. |
InverseOption | Specifies whether to consider inverse formats when reading number plates. |
Location | The location in which you are reading number plates. |
MaxCharHeight | The maximum height of the main characters on the number plate. |
MinCharHeight | The minimum height of the main characters on the number plate. |
MinRead | The minimum number of frames in which a plate must be visible before a result is returned, when Integration=moving . |
MinValidScore | The average character score required for a number plate to be recognized. |
OutputAllIntResults | Specifies whether to return all results, when integration returns more than one result, all for the same plate in the image. |
OutputUnformattedReads | Specifies whether to include unformatted results in the output. These are results where the number plate exceeds the confidence score specified by MinValidScore, but does not match one of the expected formats. |
PlateSizeUnit | The units used to specify the expected size of number plates (pixel or percent ). |
Region | The Region of Interest (ROI) to monitor for number plates. |
RegionUnit | The units used to specify the position and size of the region of interest (pixel or percent ). |
RejectReadsWithInvalidGaps | Specifies whether to reject number plate reads with gaps in the wrong place. |
RepeatDelay | The amount of time, in seconds, that must pass after a number plate leaves the scene, before the same number plate can be reported again. |
Sensitivity | The confidence level required to detect a number plate. |
ThreadCount | The maximum number of threads to use to detect and read number plates. |
Type | The analysis engine to use. Set this parameter to NumberPlate . |
WeightsFiles | A list of weights files to use for reading number plates. |
Output track | Type | Description | Output1This column indicates whether the information contained in the track is included by default in the output created by an output task (when you don't set the Input parameter for the output task). |
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Data
|
NumberPlateResult | Contains a record for each number plate that is detected. Multiple records are created if the same number plate appears in consecutive frames. | No |
DataWithSource
|
NumberPlateResultAndImage | Contains the same information as the Data track, but each record also includes the source frame. |
No |
Event
|
NumberPlateEvent | Media Server creates a record in this track when a number plate appears or disappears. | Yes |
Result
|
NumberPlateResult | Contains a single record for each recognized number plate (the same number plate is likely to appear in many consecutive frames). This track only contains the best result from running number plate recognition and integration. | Yes |
ResultWithSource
|
NumberPlateResultAndImage | Contains the same information as the Result track, but also includes the best source frame. |
No |
Field name | Type | Description |
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id | UUIDData | A unique identifier to identify the number plate (there is one UUID per plate; records with the same UUID represent the same number plate in different frames) |
numberplate | NumberPlateData | Information about the number plate |
resultstatus | String | The type of result obtained (none/detect/read) |
integrationstatus | String |
The status of integration at this record:
|
NumberPlateEvent
Field name | Type | Description |
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id | UUIDData | A universally unique identifier to identify the number plate. |
event | TrackingEventData | The type of event (begin/end), and the elapsed time since the number plate appeared. |
resultstatus | String | The type of result obtained (none/detect/read) |
Field name | Type | Description |
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id | UUIDData | A unique identifier to identify the number plate (there is one UUID per plate; records with the same UUID represent the same number plate in different frames) |
numberplate | NumberPlateData | Information about the number plate |
resultstatus | String | The type of result obtained (none/detect/read) |
integrationstatus | String |
The status of integration at this record:
|
image | ImageData | The source frame |
Field name | Type | Description |
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platecenter | PointData | The position of the center of the number plate |
plateregion | PolygonData | A polygon describing the position of the number plate |
binarizethreshold | Integer | The binarize threshold used to read the number plate |
plateread | String | The characters read from the number plate |
platetype | String | The plate type (regular or square) |
platetypecode | String | The number plate type code, which specifies the positions of subreads and logos in relation to the main characters. |
country | String | The name of the country from which the number plate originates. |
state | String | The state, determined from the number plate. This field is only used for some locations, for example number plates from the United Arab Emirates. |
subread | String | The sub-read from the number plate. This field is only used for some locations, for example number plates from the United Arab Emirates. |
vehicletype | String | The vehicle type (private, taxi, military, and so on), determined from the number plate. |
score | Integer | The confidence score for number plate recognition, or for the integration process if this record is a result |
minscore | Integer | The minimum score for number plate recognition during the current integration process |
alternativeresults | String | A possible alternative result. Media Server only includes an alternative result if integration produces two possible results and you set the OutputAllIntResults parameter to TRUE . |
numreadframes | Integer | The number of frames that were analyzed to produce the result. |
mincharheight | Integer | The minimum character height detected by ANPR for this result. |
maxcharheight | Integer | The maximum character height detected by ANPR for this result. |
horiztransscore | Integer | The horizontal score for this result. This value can be useful when setting the Sensitivity. This score must be higher than the Sensitivity for ANPR to consider the plate valid. |
verttransscore | Integer | The vertical score for this result. This value can be useful when setting the Sensitivity. This score must be higher than the Sensitivity for ANPR to consider the plate valid. |
invalidgaps | Boolean | Specifies whether the result contains invalid gaps that would cause the result to be rejected if RejectReadsWithInvalidGaps=TRUE . |
finaldata | Boolean | This field specifies whether the record is the final record in a series used for integration. |
rawread | String | The characters read from the number plate by optical character recognition. This field can contain a different value to the plateread field because it shows the characters read from the plate before the expected plate formats are applied. |
unformattedread | Boolean | Indicates whether the result is "unformatted" (does not match any of the expected formats). These results are normally rejected and only appear in the output when you set OutputUnformattedReads to TRUE . |
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