ArcGIS Velocity supports geofencing and dynamic geoefencing in several of the real-time and big data analytic tools.
What is geofencing?
Geofencing is a quintessential form of real-time spatial analysis in which features (often track points) are assessed against areas of interest (often polygon areas). Most commonly, point-based observations are analyzed to determine if they have entered or exited a virtual perimeter.
In several real-time and big data analytic tools, geofencing can be performed to identify certain spatial relationships that may occur between features in a target feed or data source and a set of spatial join features, or geofences. The features used as geofences should be connected to the join port of the geofencing tool. Geofences can be points, lines or polygons. The spatial relationships available will depend on the geometry type of the input target and join data.
Example use cases for geofencing include:
- A logistics company wants to detect when a delivery vehicle is within 5 minutes of a delivery destination in order to send a message to the recipient.
- Target data: a feed of the delivery vehicle locations.
- Join data (geofences): a feature layer containing 5-minute drivetime polygons, pre-generated using ArcGIS network analysis tools.
- An airport wants to turn on the automated landing lights when an aircraft is inside its airspace.
- Target data: a feed of aircraft positions.
- Join data (geofences): a feature layer containing the authoritative airspace polygons.
- A shipping company wants to track and detect when its vessels have deviated from their planned routes.
- Target data: a feed of AIS ship positions.
- Join data (geofences): a feature layer containing pre-generated expected routes for each ship, or a buffer around these routes.
Real-time and big data analytic tools that support geofencing include:
If the join features (the geofences) do not change, a static data source should be used for the best performance. When a static data source is used, join features are ingested once when the analytic starts and are not refreshed again until the analytic restarts.
What is dynamic geofencing? (BETA)
In several real-time analytic tools, dynamic geofencing can be performed to identify spatial relationships between features in a target feed and a set of features in another, join feed (the geofences), both of which are updating in real-time or near real-time. The tool performing the geofencing uses the most recent observation of any given track ID as geofences.
- If a feed is connected to the join port, the join features (the geofences) are continuously refreshed based on the incoming features in the join feed. In this case, geofencing will be performed dynamically based on the changing features in both the target and join feeds.
- With dynamic geofencing, the Join Time Window parameter is required.
- If the join feed does not have a field tagged END_TIME, and the last known observation for a join feature is older than the specified join time window, the observations will be purged from the tool's memory and will not be included in the analysis.
- If the join feed has a field tagged END_TIME, the feature will age out of the geofence store according to the value in the field tagged as END_TIME or at the close of the join time window, whichever comes first.
Examples use cases for dynamic geofencing include:
- Analysts tracking vehicle activity want to define, modify, and delete areas of interest to detect entering and exiting vehicles. This includes updating areas of interest as they are created, updated, and deleted by the analysts and sending alerts to the appropriate analyst when a vehicle enters or exits any of the active watch zones. In this example the dynamic geofencing tool uses continuously updated geofences, the active watch zones, as the analysts modify them.
- A logistics company wants to continuously track and monitor a data feed of severe weather polygons and alert their pilots in-flight who are within a certain proximity to a storm. In this case the aircraft feed would be the target data and the weather areas would be the join data, or geofences. As weather information updates, the geofencing tool can identify those aircraft impacted.
- A city's transportation department tracks their maintenance vehicles in one feed and also receives a feed of events that might impact or even endanger the vehicle or driver such as traffic jams, accidents, protests, or police activity. With each new vehicle observation, a dynamic geofencing tool identifies the nearest event (geofence) that has occurred within the last 15 minutes and the distance between the vehicle and that event.
Real-time analytic tools that support dynamic geofencing include:
- Calculate Distance
- Filter by Geometry
- Join Features
- At a future release, Detect Incidents will be enhanced to support dynamic geofencing.
In the current release, dynamic geofencing is currently in beta and should not be used in production workflows.