Overview

The Occupancy Monitor (previously known as Queue Length Counter) node keeps track of the number and how long each detected, tracked object has been present in the specified region in the video, can highlight objects and generate max time alarms, and adds the queue analytics metadata to the frame metadata.

This node generates diverse queue metrics: the total number of objects served, the minimum and maximum queue size, the number of objects that waited on queue more than a pre-specified time (so-called alarms), the minimum, maximum and mean waiting time, etc.

This node requires a AI Model Node and a Track Objects Node before it in order to function properly.

Inputs & Outputs

Inputs : 1, Media Format : Raw Video
Outputs : 1, Media Format: Raw Video
Output Metadata : Queue Information

Properties

Property	Value
`roi_labels`	Comma separated list of labels for each ROI in the `rois` list above. Format: `label1, label2` Ex: `queue_entrance, queue_store`
`rois`	Semicolon separated list of areas in the video within which the node tracks these objects. If none is specified, the Queue Length Counter tracks objects within the entire frame. Format: `left1,top1,right1,bottom1; left2,top2,right2,bottom2` Ex: `10,10,100,100; 200,200,300,300`
`objects_to_track`	Comma separated list of Detected Object labels to track, as specified in Model Labels ex. `car, person` Accepted formats: `object_label`: any object of this type, with or without a classifier attribute. Example: `car` `object_label.class_type`: any object of this type that has a specific classifier attribute. Example: `car.red` `object_label.`: any object of this type that has at least one classifier attribute. Example: `car.` (this will match `car.red`, `car.yellow`, etc)
`min_queue_activation_time`	The minimal time in seconds a object should be present in the queue in order be considered on the analytics. Ex: `10`
`presence_threshold`	Creates an alarm and shows an orange bounding box around object if present more than these seconds in the ROI Ex. `60`
`max_occupancy_threshold`	Set a trigger when number of objects in the ROI exceeds, or drops below this threshold Ex. 10 Output metadata fields: `objects_above_max_occupancy_count` `occupancy_above_max_threshold_delta` `occupancy_below_max_threshold_delta`
`crossing_buffer`	The interval (in seconds) during which an object will not be repeat counted if it leaves and reenters the ROI Ex. `0.5`
`display_roi`	Boolean. If true, ROI info will be drawn on video Ex. `true` / `false`
`display_objects`	Boolean. If true, Object info (presence duration, as well as highlight when it crosses presence threshold) will be drawn on video Ex. `true` / `false`
`persistent_storage`	Boolean. If true, the following analytics will be stored in disk and restored when the pipeline restarts: [roi_label]['queue_total_objects_served'] [roi_label]['queue_total_max_wait_alarms'] [roi_label]['queue_size_min'] [roi_label]['queue_size_max'] [roi_label]['queue_min_wait_time'] [roi_label]['queue_max_wait_time'] [roi_label]['queue_mean_wait_time'] Ex. `true` / `false`

Metadata

Metadata Property	Description
`nodes.<node_id>`	Describes the Queue ROIs monitored by this node, and their properties. Format : as defined in the table below. `<node_id>` for Queue Length Nodes is of the form `annotate_queueX` (ex. `annotate_queue1`)

Example

"nodes": {
    "annotate_queue1": {
        "type": "annotate_queue",
        "rois": {
            "<roi_label>": {
                "coords": [
                    [468, 172],
                    [597, 307],
                    [912, 206],
                    [1227, 277],
                    [1247, 135],
                    [1054, 91],
                    [946, 121],
                    [797, 87],
                    [645, 104],
                    [468, 172]
                ],
                "current_queue_size": 1,                  
                "max_queue_size": 2,
                "max_wait_time": 15,
                "mean_wait_time": 12,
                "min_queue_size": 0,
                "min_wait_time": 5,
                "objects_above_max_occupancy_count": 0,
                "objects_above_max_waiting_time_count": 1,
                "objects_above_max_waiting_time_delta": 0,
                "objects_entered_delta": 0,
                "objects_exited_delta": 1,
                "occupancy_above_max_threshold_delta": false,
                "occupancy_below_max_threshold_delta": false,
                "total_served": 0,
                "wait_alarms": 2,
                "current_objects": {
                    "<object_tracking_id>": {
                        "first_seen": 19.0,
                        "first_seen_utc": "2022-10-21T16:16:06.363395Z",
                        "time_present": 10.0
                    }
                },
                "exited_objects": {
                    "<object_tracking_id>": {
                        "first_seen": 13.0,
                        "first_seen_utc": "2022-10-21T16:16:05.072938Z",
                        "time_present": 15.933
                    }
                }                  
            }
        }
    }
}

Format

Key	Type	Description
`<roi_label>`	Array of dictionaries	Contains information about this specific ROI
`<roi_label>.coords`	Dictionary	Contains the bounding box coordinates that represent this ROI
`<roi_label>.total_served`	Integer	Number of objects seen in this ROI since the start of the pipeline
`<roi_label>.wait_alarms`	Integer	Total number of wait alarms generated. This counter is incremented every time an object reaches the maximum waiting time defined in the node properties.
`<roi_label>.current_queue_size`	Integer	Current number objects in queue
`<roi_label>.objects_entered_delta`	Integer	Number of objects that entered the ROI between last frame and this frame
`<roi_label>.objects_exited_delta`	Integer	Number of objects that left the ROI between last frame and this frame
`<roi_label>.objects_above_max_waiting_time_count`	Integer	Number of objects currently inside the ROI above the specified temporal threshold
`<roi_label>.objects_above_max_waiting_time_delta`	Integer	Number of new objects that exceeded the threshold between the last frame and this frame
`<roi_label>.objects_above_max_occupancy_count`	Integer	Number of new objects that exceeded the max occupancy threshold
`<roi_label>.occupancy_above_max_threshold_delta`	Bool	True when the total number of objects is above the max occupancy threshold
`<roi_label>.occupancy_below_max_threshold_delta`	Bool	True when the total number of objects is below the max occupancy threshold
`<roi_label>.min_queue_size`	Integer	Minimum number of objects in queue
`<roi_label>.max_queue_size`	Integer	Maximum number of objects in queue
`<roi_label>.min_wait_time`	Integer	The minimum queue waiting time in seconds
`<roi_label>.max_wait_time`	Integer	The maximum queue waiting time in seconds
`<roi_label>.mean_wait_time`	Integer	The mean queue waiting time in seconds
`<roi_label>.current_objects`	Array of dictionaries	Information about the objects currently in the ROI `object_tracking_id` : Unique identifier for a specific object, as specified by `object.id` property (see AI Model Node ) `first_seen` : Time in seconds (since start of deployment) when the object was first seen in the ROI `first_seen_utc` : UTC time in ISO 8601 format when the object was first seen in the ROI `time_present` : Time in seconds that the object has been present in the ROI
`<roi_label>.exited_objects`	Array of dictionaries	Information about the objects that left the ROI in the previous frame `object_tracking_id` : Unique identifier for a specific object, as specified by `object.id` property (see AI Model Node ) `first_seen` : Time in seconds (since start of deployment) when the object was first seen in the ROI `first_seen_utc` : UTC time in ISO 8601 format when the object was first seen in the ROI `time_present` : Time in seconds that the object was present in the ROI