akeil / OwnZone

Named geographic zones from OwnTracks messages

OwnZone

This is a small tool to convert location messages from an OwnTracks app to named "zones".

OwnZone runs as a service in the background and connects to an MQTT broker where it subscribes to messages with location info (lat/lon coordinates) and publishes messages with corresponding zone names.

Configuration

OZ needs a configuration file with the following contents:

MQTT Topics

We rely on the OwnTracks topic structure which constructs topics like this:

<prefix>/<user>/<device>

The prefix must be set in appsettings under Engine.TopicPrefixIn. OwnZone will derive the username from the incoming OwnTracks messages and publish to the following topics:

<prefix>/<user>/current
<prefix>/<user>/status/<zone>

The prefix for outgoing messages is defined in appsettings under Engine.TopicPrefixOut.

Zones

OwnZone supports the following types of zone definitions:

• Point with radius
• Bounding Box

Zones are defined in GeoJSON format as a FeatureCollection, each zone is represented by a Feature.

The FeatureCollection must have a default property topic which denotes the MQTT topic to subscribe for location updates.

The zones are described as individual Features. The features require some additonal properties to describe the zone.

• Point with mandatory properties radius (int) and name (string).
• LineString with mandatory properties padding (int) and name (string).

{
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [100.0, 50.0]
            },
            "properties": {
                "name": "my zone",
                "radius": 50
            }
        },
        {
            "type": "Feature",
            "geometry": {
                "type": "LineString",
                "coordinates": [
                    [100.0, 50.0],
                    [101.0, 51.0],
                    [102.0, 52.0]
                ]
            },
            "properties": {
                "name": "commute",
                "padding": 20
            }
        }
    ]
}

Filters

Location updates can be filtered by the following criteria:

• Accuracy If an update has an accuracy rating, drop updates with low accuracy. Accuracy is specified in meters.
• Age Ignore location updates which are too old (e.g. messages that took a long time in transport). The message must carry a UTC timestamp for thius filter to work.

Filters are part of the appsettings.json:

    "Filters": {
        "MaxAge": "1:30:00",
        "MaxAccuracy": 25
    }