Tanker Polygon Events

The Polygon Event API enables historical and real-time tracking of tanker and gas vessels as they enter or exit defined maritime zones such as ports, canals, anchorages, terminals, and shipyards. Leveraging over 12 years of AXSMarine’s proprietary AIS data, this API provides structured insights into vessel movements across 60,000+ geofenced polygons.

A Polygon Event represents a vessel’s movement through a strategically defined maritime zone, triggered when the vessel enters and exits the area. Each event is captured through two key AIS signals: entry (the first AIS signal detected within the polygon) and out (the last AIS signal before the vessel leaves the polygon), as reflected in the API response.

Key Features

🚢 Vessel Activity Insights – Identify when a vessel enters and exits a geofenced area using the first and last AIS signals within the polygon. Each “Polygon Event” captures both entry and out parameters, providing a detailed snapshot of vessel operations.

📍 Geofenced Tracking – Monitor tanker and gas vessel movements across anchorages, canals, terminals, and more, using AXSMarine’s polygon-based detection system.

⏱ Event Duration – Calculate how long a vessel remains in a given zone, supporting congestion assessment, operational benchmarking, or loading/discharging activity tracking.

📊 Time Series Ready – Leverage historical Polygon Events to generate time series charts showing port activity, vessel throughput, and duration trends.

🚨 Activity Alerts – Detect live “open” events and trigger alerts when vessels enter or remain in key maritime zones.

🎯 Flexible Filtering – Query by:

• Vessel specifications (IMO, DWT, etc.)
• Polygon attributes (ID, name, type)
• Entry/exit timestamps and AIS signal data
• Filtering with is_open_event = true is recommended for tracking real-time vessel activity.

📚 Deep Historical Coverage – Access over 12 years of event data for tanker and gas vessels—ideal for forecasting, trend analysis, and operational intelligence.

📦 Efficient Pagination – Manage large datasets using link-based pagination via the "links" object (e.g., { "next": "" }). Results are limited to 10,000 events per page. For handling large datasets, refer to the pagination section.

🧾 Flat Response Format – Designed for easy integration with spreadsheets, BI dashboards, and time series platforms. The API returns a flat, structured response ideal for analytics and reporting.

Filter by ancestors

The ancestor_polygons parameter is a new filter introduced in the v5 API. It allows you to target events based on the parent (or “ancestor”) of the polygons that contain the event, something that wasn’t possible with the existing parameters in v4.

What it does exactly

• Filters events whose polygon lies inside a parent polygon (e.g., a port, zone).
• Considers the parent polygon’s type via the polygon_types option. In other words, you must first specify the type of polygon you’re looking for (port, berth, etc.) and then provide the corresponding parent identifiers.

Accepted value formats

You can provide these values in two ways:

1. Comma‑separated list ancestor_polygons=NL,NLRTM
2. Repeated parameter ancestor_polygons=NL&ancestor_polygons=NLRTM

Example request

https://apihub.axsmarine.com/tanker/ais/event/polygon/v5?polygon_types=zone&ancestor_polygons=NLRTM&page_size=50

In this example, the call will return events located in zone polygons that are contained within the parent polygons identified by the LOCODE NLRTM.

Why it’s useful

• Hierarchical geographic search – you can filter events not only by the polygon of interest but also by the larger geographic area that surrounds it.
• Noise reduction – by combining polygon_types and ancestor_polygons, you limit results to relevant child polygons of a given geographic structure.

In summary, ancestor_polygons adds a layer of hierarchical filtering to requests, improving the accuracy and relevance of results obtained via the v5 API.