Geofences in the field

Restricted zones are meant to warn the operator at the moment; operations zones mainly add context on the web map.

On-device evaluation uses geometry synced from the server—keep a good GPS fix and open the app with network at least once to refresh zones.

A restricted zone only fulfills its purpose if the operator finds out at the moment, not hours later in a log review. That's why the Sentinel mobile app continuously evaluates GPS position against synced restricted zones and triggers a local notification when the operator crosses the border. That notification appears even with the app in background, as long as the OS allows it.

Experience quality depends on two things the operator controls: good GPS signal and granted location permission when the app asked. If GPS is degraded (indoors, deep valley, weather conditions) evaluation loses precision and false positives near the border are possible. The usual practice is to draw geofences with some margin to tolerate that natural imprecision.

Operations zones work differently: they don't notify the operator, but add context in the dashboard. When an admin looks at the map, they see which unit is inside which operations zone, enriching the situation read. For the field operator, operations zones are invisible day to day—and that's intentional: avoid saturating the operator with non-actionable info.

A recommended routine: the operator opens the app at least once with network at shift start, to ensure zone list and remote config are up to date. From there they can operate offline for hours as long as GPS is valid. For very long shifts in zones without coverage, plan refresh points with network.