Zone Activity Check

The Zone Activity Check evaluates conditions at the zone level — how many tracks are in a zone and whether they meet threshold criteria. Unlike the Track Checks which evaluate individual track behavior, this node answers the question “what is happening in this zone right now?”

When to use

Use the Zone Activity Check when your workflow is triggered by zone state signals and you care about aggregate zone activity rather than individual track behavior:

Congestion — too many vehicles in an aisle zone
Congregation — multiple people gathering in an area
Occupancy limits — zone exceeds a maximum track count
Zone monitoring — any scenario where the number of objects in a zone matters

This node is designed for zone state data from the Detection Webhook Trigger with signal type set to Zone State. For track-level checks, use the Track Checks node instead.

How it works

The node reads the zone state from the input, including the list of active tracks in the zone
For each active track, it evaluates the enabled threshold conditions (dwell time, intersection)
Tracks that meet all enabled thresholds are counted as qualified tracks
The check passes if the number of qualified tracks meets the minimum track count

Configuration

Site

Select the Worlds site. This loads available zones for reference.

Threshold groups

Each group defines the conditions tracks must meet to be counted:

Parameter	Type	Description
Zone IDs	Multi-select	Which zones this group applies to. Use `={{$json.zone_state.zone_id}}` to dynamically match the incoming zone.
Min Track Count	Number	Minimum number of qualified tracks for the check to pass
Dwell Time	Toggle + value	Minimum time (seconds) a track must have been in the zone to be counted
Intersection	Toggle + value	Minimum overlap percentage between the track’s bounding box and the zone polygon

Setting the zone ID dynamically with ={{$json.zone_state.zone_id}} means the same threshold configuration applies to every zone your trigger is monitoring. This is the most common approach.

Example configuration

For a congestion workflow detecting 4+ vehicles lingering in aisle zones:

Parameter	Value
Zone IDs	`={{$json.zone_state.zone_id}}`
Min Track Count	4
Dwell Time	Enabled, >= 5 seconds
Intersection	Enabled, >= 10%

This means: the check passes when 4 or more tracks in the zone each have at least 5 seconds of dwell time and at least 10% intersection with the zone polygon.

Output

{
  "zone_state": { ... },
  "checks": {
    "zoneActivity": {
      "passed": true,
      "zone_id": "92",
      "zone_name": "Aisle-Zone-West",
      "qualified_track_ids": ["track-uuid-1", "track-uuid-2", "track-uuid-3", "track-uuid-4"],
      "qualified_track_count": 4,
      "total_active_tracks": 6,
      "track_details": {
        "track-uuid-1": {
          "tag": "forklift",
          "dwell_time": 25.0,
          "intersection": 45.3,
          "qualified": true
        }
      }
    }
  }
}

Key output fields

Field	Description
`passed`	Whether the qualified track count met the minimum threshold
`zone_id`	The zone that was evaluated
`qualified_track_ids`	Track IDs that met all threshold conditions — use these downstream for image capture and event metadata
`qualified_track_count`	Number of qualifying tracks
`total_active_tracks`	Total tracks in the zone (including those that didn’t meet thresholds)
`track_details`	Per-track breakdown showing dwell time, intersection, and whether it qualified

Downstream usage

The qualified_track_ids output is commonly used by downstream nodes:

Closest Frame — find the timestamp where qualified tracks are closest together for the best image
Process Detection Image — generate a still or GIF showing the qualified tracks
Event Manager — attach qualified track IDs to the created event

Credentials

Requires GraphQL Subscription API credentials (for loading site/zone options).

Business use case examples

Aisle congestion — 4+ vehicles lingering in a zone

Detect when multiple vehicles are lingering in a factory aisle zone, creating traffic congestion that blocks material flow.

Parameter	Value	Purpose
Zone IDs	`={{$json.zone_state.zone_id}}`	Dynamically matches incoming zone
Min Track Count	4	At least 4 vehicles to constitute congestion
Dwell Time	`>=` 5 seconds	Vehicles must be lingering, not just passing through
Intersection	`>=` 10%	Vehicles must be meaningfully inside the zone

Mode: Streaming, zone state — receives updates whenever zone occupancy changes.The workflow uses an Event Orchestrator scoped by zone (not track) to prevent duplicate congestion events. The qualified_track_ids output feeds downstream into Closest Frame (to find the best multi-track image) and Create Still (to show all qualifying vehicles with bounding boxes and zone overlay).A VLM analyzes the captured image to add context metadata (e.g., “Four vehicles visible in the aisle. Two forklifts are positioned side by side blocking the travel path…”). When vehicles leave and the count drops below 4, the orchestrator routes to the Close Event path with the congestion duration.See the Congestion Workflow guide for the full end-to-end walkthrough.

Adapting for other use cases

Zone Activity Check works for any aggregate zone monitoring scenario:

Use Case	Min Track Count	Dwell Time	Intersection	Notes
Aisle congestion	`4`	`>= 5s`	`>= 10%`	Vehicles blocking traffic
Congregation	`5`	`>= 30s`	`>= 15%`	People gathering in restricted areas
Occupancy limit	Site-specific	`>= 10s`	`>= 5%`	Maximum capacity enforcement
Loading dock queue	`3`	`>= 60s`	`>= 20%`	Vehicles waiting too long at dock

Higher dwell time thresholds filter out transient tracks (objects passing through), while higher intersection thresholds ensure the objects are meaningfully inside the zone rather than just at the boundary.

Trigger Nodes

Check Nodes

Event Nodes

Action Nodes

When to use

How it works

Configuration

Site

Threshold groups

Example configuration

Output

Key output fields

Downstream usage

Credentials

Business use case examples

​When to use

​How it works

​Configuration

​Site

​Threshold groups

​Example configuration

​Output

​Key output fields

​Downstream usage

​Credentials

​Business use case examples

When to use

How it works

Configuration

Site

Threshold groups

Example configuration

Output

Key output fields

Downstream usage

Credentials

Business use case examples