Directional Zone

This security zone type is available on the QbProtect product.

The directional security zone uses detected objects and specific object attributes (size, movement direction) at the zone’s separation plane to generate an alarm.

Application

Protected area entrance monitoring

This zone can be used to generate alarms only when objects are moving in an inbound direction. Objects moving in the opposite direction are ignored (e.g., leaving the protected area will never raise an alarm).

Parameters

See configuration API definition.

Intrusion conditions

Alarm sizes (default: LARGE, MEDIUM)

Filter objects based on size. Only objects of a selected size category can raise an alarm. The selection of multiple object size categories is allowed.

  • LARGE: Cars, groups of people or large animals (e.g., deer).

  • MEDIUM: Non-occluded individual humans, standing or crawling.

  • SMALL: Crouching humans, partially occluded persons or small animals (e.g., rabbits).

    The size category boundaries are configurable and can be adjusted.

Output options

Hold duration (default: 0, unit: \(s\))

Minimum hold time for the alarm when active. A value of 0 (default) will disable the alarm as soon as the conditions for raising the alarm are no longer met.

Linked occupancy zones (default: empty list)

List of occupancy zones. Evaluation of this zone is skipped when any of the occupancy zones are occupied. The default value (empty list) will always trigger the zone’s measurement.

Tampering

Minimum coverage (default: 0, unit: \(\%\))

The minimum percentage of the zone’s volume visible to the sensor. An object between the sensor and the zone can obstruct the visibility so that less than the specified percentage of the zone’s volume is seen by the sensor. In this case a tampering alarm is generated to indicate, that the zone’s intrusion state can not be properly evaluated anymore. The underlying calculation is based on the amount of unobstructed laser rays being able to penetrate the zone (ray casting). The default value of 0 will never raise the zone tampering alarm, even when the zone is fully obstructed. Note that a zone which configures a minimum coverage must also set a hold duration of at least 3 seconds, otherwise it is rejected.

This per zone measurement is how a covered device is detected whenever at least one zone configures a minimum coverage. If no zone does, there is nothing to measure per zone and the device falls back to the legacy signal, which evaluates the rate of points the whole device returns and reports a single verdict for it — that verdict cannot tell which zone can no longer be evaluated. The two are mutually exclusive, and because the zones carrying a coverage alarm are exactly the ones replicated to the followers, every sensor of a swarm always uses the same one.

In a swarm every sensor measures its own coverage of the zone and the leader decides over all of them: the alarm is only raised once every sensor observing the zone is below the configured minimum coverage. A zone which one sensor can no longer see, but another still can, is not tampered — its intrusion state can still be evaluated. Sensors which barely reach the zone do not take part in the decision, so a sensor which only clips a corner of it cannot suppress the alarm of one whose view is fully obstructed.

Algorithm

The algorithm uses the tracked objects from object tracking as input data. It operates in two stages:

Filter objects

This step finds the subset of all tracked objects which are currently in the vicinity of the zone. The objects are then filtered based on the parameter configured for the alarm sizes.

Detect direction

The path of the remaining objects is analyzed to detect if the most recent path segment crosses the zone’s XZ-center-plane in the positive Y-axis direction of the zone’s cuboid. All objects which satisfy this condition are listed as intruders, and the zone alarm is set to \(true\).

The alarm will remain active while any intruding object is tracked in the scene. Only when the object disappears or moves through the zone in the opposite direction the alarm is set to \(false\) again.

Output data

See output API definition.

State

alarm (\(true,false\))

The current alarm. A \(true\) value indicates an alarm.

intrusion

Unfiltered pre-alarm state from the zone’s internal alarm logic.

objects

List of objects currently traversing the zone in the inbound direction. Each entry also contains a discretized representation of the track history and a snapshot of the current point cloud.