ANPR options

Agent supports License Plate Recognition in a few ways:

  • Via PlateRecognizer.com (commercial with free tier, cross platform runs on cloud or locally, pay by volume)
  • Via AgentDVR-ALPR (free, open source, runs on Linux)
  • Via senseAI v2+ (free, open source, runs cross platform, (Agent v4.4.7.0+)).
    When you have installed senseAI you will need to install the ALPR module for it. See modules in the sense AI web interface.

Using PlateRecognizer

Configure LPR (ANPR or License Plate Recognition) in Agent DVR by going to Server Settings - AI Settings and enter the settings under Plate Recognizer. Sign up for a Free Trial on Plate Recognizer. No credit card required.

Tip: AI Server is optional - you can combine Plate Recognizer with AI by triggering LPR on Alert and using an AI Server to filter movement alerts to "car,motorbike". See AI

Configuring LPR Server

  • URL: This is the URL to the service. The default is "https://api.platerecognizer.com/v1/plate-reader/" but you can enter your own server if you have your own instance of it running.
  • Token: After creating a Plate Recognizer account, go to the Plate Recognizer Account Page and copy the API Token value.
  • Regions: Leave this blank for default or enter a CSV list of regions
  • Config: You can enter an extra config value here from the docs
  • Important: As of v4.4.7.0+ the following options have moved to the camera configuration
  • License Plates: Enter a CSV list of plates to recognise. Example: abc123,def234,efg345 OR a URL to a dynamic list of plates like http://myserver/plates.txt. This is used to raise events from the camera like Recognized or Not Recognized. If this is blank all plates will generate Not Recognized events.
  • Reload Interval (s): If you are using a URL in License Plates this controls how often to reload the list from the URL.
  • Normalize: Enable this to normalize the plates when doing lookups. This will replace I with 1, B with 8, O with 0, Z with 2 and S with 5. This helps guard against frequently misread plate characters as both the plate lookup and the plate list are normalized.
LPR Camera Configuration

Once the server settings are done, edit a camera and go to the LPR tab:

  • Enabled: Switch LPR on or off. You can also do this via the Schedule
  • Mode: Choose between Motion, Alert, Interval or None. Motion and alert only process when something is happening (remember to setup a motion detector on the Detector tab and make sure it is enabled). Interval will constantly send frames to the LPR service. Use None if you only want to process using the API.
    Tip: You can use DeepStack Alert Filtering to have DeepStack look for "car,motorcycle" and then trigger when an alert is detected and passes the filter to minimise the number of requests.
  • Minimum Interval: How often to send images to the web service when triggered. The free version of PlateRecognizer.com has a limit of 2500 requests per month and a rate limit of 1 frame per second. (this may change, check their website)
  • AI Server: Choose from Default, PlateRecognizer or a senseAI server. Default will use PlateRecognizer if you have configured it in server settings otherwise it will default to the first AI server you have added.
  • License Plates:Enter a CSV list of plates to recognise. Example: abc123,def234,efg345 OR a URL to a dynamic list of plates like http://myserver/plates.txt. This is used to raise events from the camera like Recognized or Not Recognized. If this is blank all plates will generate Not Recognized events.
  • Reload Interval : If you are using a URL in License Plates this controls how often to reload the list from the URL.
  • Normalize: Enable this to normalize the plates when doing lookups. This will replace I with 1, B with 8, O with 0, Z with 2 and S with 5. This helps guard against frequently misread plate characters as both the plate lookup and the plate list are normalized.
  • Confidence: Minimum confidence of result. Anything below this value will be discarded (0-100)
  • Photos: Check this to take a photo. These photos will be saved to Photos in Agent DVR.
  • Label: Check this to label the photo with results.
  • Make, Model and Color: Check this only if you have a paid plan that supports it on PlateRecognizer.com. It's not included in the free plan. Make model and color will be requested with the image and returned in {AIJSON} in Agent Actions (see below).
Example Photo
Example LPR Photo Result
Adding LPR Actions

When LPR runs Agent will generate events for "License Plate Recognized", "License Plate Not Recognized" and "License Plate Not Detected" under Actions. If a plate is detected that matches one in the list in the server configuration you will get a Recognized event otherwise you will get a Not Recognized event.

You can use these events to trigger actions such as calling a URL with the detected plate or running an executable or publishing a message to an MQTT server. You can use the tags {AI} for the plate details (if more than one they will be in a CSV list) or {AIJSON} for the full response JSON object from PlateRecognizer.com.

LPR Troubleshooting

If LPR isn't working check the log file at /logs.html on the local server.