JSON Group Results

Rekor Scout® generates an alpr_group JSON value for a collection of similar license plates, generally delegating a single plate group per vehicle. When the plate is not seen for a number of seconds, the plate_group result is sent with a reference (by UUID) to all the individual plate results that make up the group. The group also includes the best estimate for the license plate number based on a weighted score from all the frames included in the group.

Additionally, each plate group includes a detection value for the make/model, color, and vehicle body type.

Group results are most suitable for surveillance-type purposes. When these values are used, results may be delayed up to ten seconds after the vehicle has passed, so it is important that the application is not sensitive to this delay. If more real-time results are needed, it is recommended that you ignore the plate_group value and use only the individual plate results.

ALPR group results are sent in the following JSON format:

{
   "epoch_end" : 1562681124479,
   "best_image_height" : 2160,
   "best_image_width" : 4096,
   "best_region_confidence" : 57.2820510864258,
   "is_parked" : false,
   "agent_type" : "alprd",
   "data_type" : "alpr_group",
   "gps_latitude" : 37.635986328125,
   "frame_start" : 0,
   "best_region" : "us-mo",
   "agent_uid" : "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY",  # Taken from /etc/openalpr/install_id
   "agent_version" : "2.7.101",
   "country" : "us",
   "uuids" : [
      "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY-1234-1562681121543",
      "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY-1234-1562681121504",
      "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY-1234-1562681121576"
   ],
   "plate_indexes" : [
      0,
      0,
      0
   ],
   "frame_end" : 72,
   "epoch_start" : 1562681121504,
   "vehicle_crop_jpeg" : "...base64 jpeg data...",
   "version" : 2,
   "candidates" : [
      {
         "matches_template" : 0,
         "plate" : "D2651BF",
         "confidence" : 93.877067565918
      },
      {
         "plate" : "D2651F",
         "matches_template" : 0,
         "confidence" : 74.8114395141602
      },
      {
         "confidence" : 73.527099609375,
         "plate" : "D265BF",
         "matches_template" : 0
      }
   ],
   "best_uuid" : "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY-1234-1562681122676",
   "gps_longitude" : -79.2059326171875,
   "vehicle" : {
      "orientation" : [
         {
            "name" : "270",
            "confidence" : 48.2063217163086
         },
         {
            "confidence" : 41.217414855957,
            "name" : "90"
         }
      ],
      "color" : [
         {
            "name" : "black",
            "confidence" : 27.3192367553711
         },
         {
            "confidence" : 26.2272186279297,
            "name" : "silver-gray"
         }
      ],
      "make_model" : [
         {
            "confidence" : 3.64025783538818,
            "name" : "ford_focus"
         },
         {
            "name" : "chevrolet_cruze",
            "confidence" : 2.92206859588623
         }
      ],
      "make" : [
         {
            "confidence" : 18.9258556365967,
            "name" : "ford"
         },
         {
            "confidence" : 6.7553653717041,
            "name" : "chevrolet"
         },
         {
            "confidence" : 6.33295917510986,
            "name" : "toyota"
         }
      ],
      "year" : [
         {
            "name" : "2010-2014",
            "confidence" : 54.3283767700195
         },
         {
            "confidence" : 27.7071475982666,
            "name" : "2015-2019"
         }
      ],
      "body_type" : [
         {
            "name" : "sedan-standard",
            "confidence" : 51.1733474731445
         },
         {
            "name" : "sedan-compact",
            "confidence" : 14.3800678253174
         }
      ]
   },
   "best_confidence" : 93.877067565918,
   "best_plate_number" : "D2651BF",
   "company_id" : "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
   "matches_template" : false,
   "travel_direction" : 85.5532836914062,
   "camera_id" : 1234,
   "best_plate" : {
      "matches_template" : 0,
      "plate_index" : 0,
      "region_confidence" : 62,
      "plate" : "D2651BF",
      "plate_crop_jpeg" : "...base64 jpeg data...",
      "confidence" : 93.877067565918,
      "coordinates" : [
         {
            "y" : 187,
            "x" : 3274
         },
         {
            "x" : 3485,
            "y" : 192
         },
         {
            "y" : 306,
            "x" : 3480
         },
         {
            "y" : 301,
            "x" : 3266
         }
      ],
      "region" : "us-mo",
      "processing_time_ms" : 52.1168479919434,
      "candidates" : [
         {
            "plate" : "D2651BF",
            "matches_template" : 0,
            "confidence" : 93.877067565918
         },
         {
            "plate" : "D2651F",
            "matches_template" : 0,
            "confidence" : 81.3600769042969
         },
         {
            "plate" : "D265BF",
            "matches_template" : 0,
            "confidence" : 80.9256439208984
         }
      ],
      "vehicle_region" : {
         "x" : 3060,
         "height" : 630,
         "y" : 0,
         "width" : 630
      },
      "requested_topn" : 10
   }
}