Overview

The Object Flow Counter node provides a breakdown of specific object types that cross a line or a sequence of lines defined by a Line Crossing Counter node prior to it. This node makes it easy to build common use cases such as People flow mapping in retail environments, Traffic intersection analysis, etc.

This node requires a Line Crossing Counter before it in order to function properly.

Inputs & Outputs

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

Properties

Property	Description	Type	Default	Required
`object_types`	ex. `car`,`person`,`face.mask`. Comma-separated list of object types to consider.	model-labels	`null`	Yes
`object_flow_rules`	Comma-separated list of labels of lines (ex `line_entrance`), line pairs (ex `lineA+lineB`), lines with direction labels (ex `lineA:dir1`) or direction labels (ex `dir1`) from previous Line Crossing Counter nodes that an object must cross through to be counted. If empty, counts across all lines.	`string`	`null`	No
`line_distance`	Optional physical distance between two lines used to calculate object speeds for multi-line rules.	`number`	`null`	No
`line_distance_unit`	Unit for line distance conversion when calculating speed. Options: Meters (kmph) (`meters`); Feet (mph) (`feet`).	`enum`	`feet`	No
`speed_trigger_threshold_high`	Classify measured speeds at or above this threshold as high speed. Uses mph for feet and kmph for meters.	`float`	`100.0`	Yes
`speed_trigger_threshold_low`	Classify measured speeds below this threshold as low speed. Uses mph for feet and kmph for meters.	`float`	`20.0`	Yes
`reset_trigger`	Accumulate crossed object counts until this condition evaluates to true.	trigger-condition	`null`	No
`display`	Display. Options: None (`none`); Basic (`basic`).	`enum`	`basic`	No

Notes:

Use the reset_trigger to reset object counts when this condition evaluates to true. ex. nodes.time_trigger1.triggered. Use it in combination with a Time Trigger to accumulate statistics over a regular interval like 5 minutes.

Output Metadata

The fields below are declared by this node's metadata schema; the JSON values are representative examples.

Path	Type	Description
`nodes.<node_id>.total_objects_crossed_delta`	`integer`	Number of objects seen crossing all monitored rules between last frame and this frame
`nodes.<node_id>.total_objects_crossed_count`	`integer`	Number of objects seen crossing all monitored rules since last time stats were reset
`nodes.<node_id>.lines.<object_flow_rule>.total_objects_crossed_delta`	`integer`	Number of objects seen crossing all monitored rules between last frame and this frame
`nodes.<node_id>.lines.<object_flow_rule>.total_objects_crossed_count`	`integer`	Number of objects seen crossing all monitored rules since last time stats were reset
`nodes.<node_id>.lines.<object_flow_rule>.object_crossed_deltas.<object_label>`	`string`	When one or more objects of this label cross the specified rule
`nodes.<node_id>.lines.<object_flow_rule>.object_crossed_counts.<object_label>`	`string`	Cumulative crossing count for this object label.
`nodes.<node_id>.lines.<object_flow_rule>.object_speeds_min.<object_label>`	`string`	Minimum measured speed for this object label.
`nodes.<node_id>.lines.<object_flow_rule>.object_speeds_max.<object_label>`	`string`	Maximum measured speed for this object label.
`nodes.<node_id>.lines.<object_flow_rule>.object_speeds_avg.<object_label>`	`string`	Average measured speed for this object label.
`nodes.<node_id>.lines.<object_flow_rule>.objects_low_speed_count`	`integer \| null`	For multi-line speed rules, number of currently visible objects classified as low speed; otherwise `null`.
`nodes.<node_id>.lines.<object_flow_rule>.objects_low_speed_delta`	`integer \| null`	Number of visible objects newly entering the low-speed category for this rule; otherwise `null`.
`nodes.<node_id>.lines.<object_flow_rule>.objects_medium_speed_count`	`integer \| null`	For multi-line speed rules, number of currently visible objects classified as medium speed; otherwise `null`.
`nodes.<node_id>.lines.<object_flow_rule>.objects_medium_speed_delta`	`integer \| null`	Number of visible objects newly entering the medium-speed category for this rule; otherwise `null`.
`nodes.<node_id>.lines.<object_flow_rule>.objects_high_speed_count`	`integer \| null`	For multi-line speed rules, number of currently visible objects classified as high speed; otherwise `null`.
`nodes.<node_id>.lines.<object_flow_rule>.objects_high_speed_delta`	`integer \| null`	Number of visible objects newly entering the high-speed category for this rule; otherwise `null`.
`nodes.<node_id>.lines.<object_flow_rule>.crossed_objects`	`array`	Array of tracking IDs for objects that crossed this flow rule.
`nodes.<node_id>.lines.<object_flow_rule>.speed_unit`	`string`	Unit used for reported object speeds.
`nodes.<node_id>.type`	`string`	Identifies the node type that produced this metadata.

JSON example

{
  "nodes": {
    "object_flow1": {
      "lines": {
        "object_flow_rule": {
          "crossed_objects": [ <object_tracking_id>,<object_tracking_id> ],
          "object_crossed_counts": {
            "object_label": "example"
          },
          "object_crossed_deltas": {
            "object_label": "example"
          },
          "object_speeds_avg": {
            "object_label": "example"
          },
          "object_speeds_max": {
            "object_label": "example"
          },
          "object_speeds_min": {
            "object_label": "example"
          },
          "objects_high_speed_count": 0,
          "objects_high_speed_delta": 0,
          "objects_low_speed_count": 0,
          "objects_low_speed_delta": 0,
          "objects_medium_speed_count": 0,
          "objects_medium_speed_delta": 0,
          "speed_unit": "mph",
          "total_objects_crossed_count": 0,
          "total_objects_crossed_delta": 0
        }
      },
      "total_objects_crossed_count": 0,
      "total_objects_crossed_delta": 0,
      "type": "object_flow"
    }
  }
}

Object labels and attributes

Object labels/classes added: None.
Object attribute labels/classes added: Line-crossing labels use class 12000. When line_distance is configured, the latest calculated speed value uses class 12001 and the latest speed-category label (speed_low, speed_medium, or speed_high) uses class 12400; both remain attached whenever the tracked object is visible.