Overview

The Line Counter node keeps track of the number of objects that cross a virtual line in the video, the direction they cross it in, and adds the line counting metadata to the frame metadata. This node makes it easy to build common use cases such as People counting, Parking lot occupancy counting, etc.

This node supports Lines with one or more segments, allowing you to be as granular as you need for your counting needs.

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 : Line Counter Information

Properties

Property	Description	Type	Default	Required
`line_labels`	List of labels for each line.	list	null	Yes
`lines`	List of lines in the video across which objects will be tracked. Each line can have multiple segments defined by two or more points (x1,y1,x2,y2,x3,y3). Must correspond to labels defined in `line_labels`.	multiline	null	Yes
`objects_to_track`	Object types and classes to be counted. Accepts object labels defined in the AI model (e.g. 'car', 'person') and classifier attributes (e.g. 'car.red'). Leave blank to count all objects.	model-label	null	No
`crossing_buffer`	Interval in seconds during which subsequent line crossings by the same object will be ignored.	float	0.5	Yes
`display_line`	Controls whether line information will be displayed on the video stream.	bool	true	No
`display_objects`	Controls whether objects will be displayed on the video stream.	bool	true	No
`tracking_mode`	Point on object used to determine line crossing. Options: "centroid", "top-center", "bottom-center", "left-center", "right-center".	enum	"centroid"	No
`dir1_label`	Label for Direction 1 (blue color in the lines widget).	string	null	No
`dir2_label`	Label for Direction 2 (red color in the lines widget).	string	null	No
`add_object_attributes`	Add specified labels as attributes to objects that cross the line. Options: "none", "direction", "line", "line_direction".	enum	"none"	No
`persistent_storage`	If true, analytics will be persisted to disk and restored when pipeline restarts.	bool	false	No

Metadata

Metadata Property	Description
`nodes.<node_id>`	Describes the Lines monitored by this node, and their properties. \nFormat : as defined in the table below. \n \n`<node_id>` for Line Counter Nodes is of the form `annotate_line_counterX` (ex. `annotate_line_counter1`)

Example

"nodes": {
    "annotate_line_counter1": {
        "type": "annotate_line_counter",
        "lines": {
            "<line_label>": {
                "dir1_label": "entry",
                "dir2_label": "exit",
                "coords": [[<point1_x>, <point1_y>],[<point2_x>, <point2_y> ]],
                "total_objects_crossed": <number>,
                "total_objects_crossed_delta": <number>,
                "dir1_objects_crossed": <number>,
                "dir1_objects_crossed_delta": <number>,
                "dir2_objects_crossed": <number>,
                "dir2_objects_crossed_delta": <number>,
                "cur_dir1_objects": [ <object_tracking_id>,<object_tracking_id> ],
                "cur_dir2_objects": [ <object_tracking_id>,<object_tracking_id>  ]
            }
        }
    }
}

Format

Key	Type	Description
`<line_label>`	Array of dictionaries	Contains information about this specific line
`<line_label>.coords`	Dictionary	Contains the coordinates for this line \n \n`point1_x`, `point1_y` : Coordinates of one endpoint \n`point2_x`, `point2_y` : Coordinates of the other endpoint
`<line_label>.total_objects_crossed`	Integer	Number of objects seen crossing this line since the start of the pipeline
`<line_label>.total_objects_crossed_delta`	Integer	Number of objects seen crossing this line between last frame and this frame (both directions)
`<line_label>.dir1_objects_crossed`	Integer	Number of objects seen crossing this line, in one direction since the start of the pipeline
`<line_label>.dir1_objects_crossed_delta`	Integer	Number of objects seen crossing this line between last frame and this frame in the direction 1
`<line_label>.dir2_objects_crossed`	Integer	Number of objects seen crossing this line, in the other direction since the start of the pipeline
`<line_label>.dir2_objects_crossed_delta`	Integer	Number of objects seen crossing this line between last frame and this frame in the direction 2
`<roi_label>.cur_dir1_objects`	List of object IDs	Information about the objects currently crossing the line in the first direction \n \n`object_tracking_id` : Unique identifier for a specific object, as specified by `object.id` property (see AI Model Node )
`<roi_label>.cur_dir2_objects`	List of object IDs	Information about the objects currently crossing the line in the other direction \n \n`object_tracking_id` : Unique identifier for a specific object, as specified by `object.id` property (see AI Model Node )