Category Archives: Angular

Displaying Plate Numbers on ALPR Cameras

I’ve been running OpenALPR on Unraid for about 6 months. Since January I’ve been working on a tool that replaces the limited closed-source OpenALPR web ui with my own OpenALPR Webhook Processor. I pointed the OpenALPR agent at my tool instead of the OpenALPR web ui. The agent sends a JSON payload defined here.

After the JSON payload is processed it is displayed through an Angular web app running on Core backend. It uses a SQLite database to store plate information, and retrieves images from the agent on the fly. It records a small amount of statistics, allows searching based on make/model and plate numbers including regular expressions, and can both ignore and alert on plates.

The home plate screen

The tool can also manage individual cameras day/night toggling and zoom/focus based on the camera GPS location:

Modifying ALPR and regular cameras

When the tool receives a webhook from the agent, it parses the plate information and overlays the text on the camera:

The agent tries to determine the make/model of the vehicle, it’s not always correct (especially at night), but it does get a fair amount of accurate results.

So far it has been working pretty well! I am currently working on a method for “scraping” the agent’s debug web ui for information instead of using webhooks. This will be useful for people with the “Homeowner” membership that requires the webhook to come from the OpenALPR cloud website.