JSON Plate Results

Rekor Scout® generates an alpr_results JSON value for every frame of video in which a license plate is recognized. This value will be sent multiple times for a single vehicle. For example, as a vehicle drives past the camera over the course of three seconds, Scout may recognize the same license plate fifty times. All fifty recognition results will be recorded as alpr_results JSON values.

The number of recognition results largely depends on the processing speed and number of cameras being processed. A faster processor will produce more of these per vehicle because it is able to process video frames at a faster rate.

Individual plate results are best suited for applications that need to operate on plate data in real time.

JSON Plate results are sent in the following format:

{
   "processing_time_ms" : 105.850112915039,
   "data_type" : "alpr_results",
   "uuid" : "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY-1234-1562681608425",
   "version" : 2,
   "camera_id" : 1234,
   "results" : [
      {
         "plate_index" : 0,
         "coordinates" : [
            {
               "x" : 3257,
               "y" : 188
            },
            {
               "x" : 3467,
               "y" : 194
            },
            {
               "x" : 3460,
               "y" : 307
            },
            {
               "y" : 302,
               "x" : 3247
            }
         ],
         "processing_time_ms" : 47.0029602050781,
         "plate_crop_jpeg" : "... base 64 image data ...",
         "plate" : "D2651BF",
         "vehicle_region" : {
            "y" : 0,
            "x" : 3042,
            "height" : 630,
            "width" : 630
         },
         "region" : "us-mo",
         "confidence" : 92.9419174194336,
         "matches_template" : 0,
         "requested_topn" : 10,
         "candidates" : [
            {
               "plate" : "D2651BF",
               "confidence" : 92.9419174194336,
               "matches_template" : 0
            },
            {
               "plate" : "D2651F",
               "matches_template" : 0,
               "confidence" : 80.8129653930664
            },
            {
               "matches_template" : 0,
               "confidence" : 80.0941772460938,
               "plate" : "D265BF"
            },
            {
               "plate" : "D251BF",
               "matches_template" : 0,
               "confidence" : 79.946403503418
            }
         ],
         "region_confidence" : 40
      },
      {
         "requested_topn" : 10,
         "candidates" : [
            {
               "matches_template" : 1,
               "confidence" : 94.7376327514648,
               "plate" : "CG3L5Y"
            },
            {
               "confidence" : 79.4123077392578,
               "matches_template" : 0,
               "plate" : "CGL5Y"
            },
            {
               "plate" : "CG3L5",
               "confidence" : 79.0777206420898,
               "matches_template" : 0
            }
         ],
         "region_confidence" : 99,
         "confidence" : 94.7376327514648,
         "region" : "us-mo",
         "matches_template" : 1,
         "plate_crop_jpeg" : "... base64 image data ...",
         "plate" : "CG3L5Y",
         "vehicle_region" : {
            "x" : 821,
            "height" : 1512,
            "y" : 0,
            "width" : 1512
         },
         "plate_index" : 1,
         "coordinates" : [
            {
               "y" : 882,
               "x" : 1419
            },
            {
               "x" : 1744,
               "y" : 893
            },
            {
               "y" : 1055,
               "x" : 1736
            },
            {
               "y" : 1044,
               "x" : 1409
            }
         ],
         "processing_time_ms" : 47.0029602050781
      }
   ],
   "agent_version" : "2.7.101",
   "error" : false,
   "company_id" : "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
   "epoch_time" : 1562681608425,
   "agent_uid" : "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY",  # Taken from /etc/openalpr/install_id
   "img_width" : 4096,
   "regions_of_interest" : [
      {
         "x" : 0,
         "height" : 2160,
         "y" : 0,
         "width" : 4096
      }
   ],
   "agent_type" : "alprd",
   "img_height" : 2160
}