The Trajectory Events Widget provides a detailed, event-based view of individual trajectories, allowing you to analyze specific events detected for each object within the monitored scene. Trajectory Events represent important moments or conditions, such as zone entries, exits, stops, or other criteria defined by the operator. They offer a structured way to capture and process these situations, replacing the functionality of the previously used Table Widget while significantly expanding its capabilities.
About Events
Events are a key data type in FLOW and provide persistent, event-oriented outputs with support for storing event history (depending on device capacity). Each event is uniquely identified by an event ID, which remains consistent across multiple runs of the FLOW BLOCK. This enables reliable referencing, improved data organization, and seamless integration with external systems via API.
Events are generated based on time-bound conditions, typically through spatial filters like gates, zones, or movements. These filters define when an event starts and when it ends, creating well-defined periods for each detected occurrence.
Each event can have three states:
Created – when a new event is detected.
Updated – when an existing event continues and its data is refreshed. Events are considered linked if they originate from the same source and their start timestamps differ by less than 100 ms.
Closed – when an event has not been updated for two processing ticks and is finalized.
This structured approach ensures that events accurately reflect real-world behaviors and allow dynamic updates as the traffic situation develops.
Available Attributes
The Events Widget supports the following attributes:
Trajectory events, covered in this article.
Nearmiss events, described in a separate article Nearmiss Events Widget [NEW].
Supported Data
The widget provides access to various trajectory attributes such as:
Object ID
Category
Speed
Acceleration
Stationary time
Duration of occurrence
…and many additional attributes, as shown in the configuration interface.
API Integration
Trajectory Events can be accessed not only via the widget interface but also through FLOW’s webhook and REST API.
The webhook interface allows you to receive event notifications in real time. You can configure whether you want to receive events when they are created, updated, closed, or any combination of these states.
The REST API provides access to both active and historical events. This allows for flexible data retrieval and integration with external applications without relying on direct widget exports.
For detailed information on working with the API, refer to the dedicated FLOW Public API article.
What Next?
Learn more about widgets and sinks in FLOW, explore time processing, or check out other widget types such as Near Miss Events and Movement Set Statistics. Use the FLOW Public API to access data from widgets and sinks and integrate it with your external systems.
Make your traffic analytics smarter and more connected with FLOW.