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How to obtain data from license plate recognition database

How to obtain data from license plate recognition database

To obtain meta data from VIT LPR database, use the following functions: itv_plate_attr_get_ex() and itv_plate_attr_get().

Note

This article implies that the reader has the basic SQL knowledge.

itv_plate_attr_get_ex()

This function searches records by the specified time range. It does not change the exported records. 

Syntax

SELECT * FROM dbo.itv_plate_attr_get_ex (
@plate NVARCHAR(16),
@from_ts DATETIME,
@to_ts DATETIME,
@image nvarchar(8)
);

Input arguments

ParameterDescription
platelicense number ( * is for "any" number)
from_ts"from" date&time; NULL can be used to not specify the "from" date&time
to_ts"to" date&time; NULL can be used to not specify the "to" date&time
image

image type:

  • "FRAME" — full image
  • "AUTO" — vehicle image (cropped)
  • "PLATE" — license plate image (cropped)
  • NULL — when specified, no image will be returned

Returned data

ParameterDescription
[GUID] UNIQUEIDENTIFIERGUID of the LPR event
[TIME] DATETIMEevent timestamp
[LPR_ID] NVARCHAR(50)ID of the LPR software instance
[PLATE] NVARCHAR(50)

license number

[frame] NVARCHAR(450)full frame ID
[auto_img] NVARCHAR(450)cropped vehicle image ID
[plate_img] NVARCHAR(450)cropped license plate image ID
[framedata] VARBINARY(MAX)binary data of the full image
[hash] XMLevent hash; format: <key>value</key>

Example

To get images (binary data), use their IDs in the following query:

SELECT [dbo].[bo_get_node_data] (@uid NVARCHAR(450));

itv_plate_attr_get()

In the database, this function marks selected LPR records as already exported and does not return them again. The function can not be used when having multiple export clients. 

Syntax

SELECT * FROM dbo.itv_plate_attr_get(
@plate NVARCHAR(16),
@image nvarchar(8)
);

Input arguments

ParameterDescription
plate

string template for a license number; * ... * is used for LIKE query, NULL is used to specify all the numbers

image

image type:

  • "FRAME" — full image
  • "AUTO" — vehicle image (cropped)
  • "PLATE" — license plate image (cropped)
  • NULL — when specified, no image will be returned

Returned data

ParameterDescription
[GUID] UNIQUEIDENTIFIERGUID of the LPR event
[TIME] DATETIMEevent timestamp
[LPR_ID] NVARCHAR(50)ID of the LPR software instance
[cam_name] NVARCHAR(100)camera name
[PLATE] NVARCHAR(50)

license number

[frame] NVARCHAR(450)full frame ID
[VALIDITY] INTrecognition accuracy
[auto_img] NVARCHAR(450)cropped vehicle image ID
[plate_img] NVARCHAR(450)cropped license plate image ID
[framedata] VARBINARY(MAX)binary data of the full image
[plate_imgdata] VARBINARY(MAX)binary data of the cropped license plate image

Note

After meta data are obtained, each of the LPR events should be marked as "already exported" with the following query: 

UPDATE dbo.PLATE_NUMBERS SET sent_st = 1 WHERE GUID = '{LPR_event_GUID}'


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