Relations

Relations are one of the main traffic analysis tools in AITracker system. They represent movement patterns and trajectories that vehicles follow through the measurement area.

What are relations?

Relations are one of the main categories by which the results in the spreadsheet can be grouped. Motion relations are defined by user-painted 'motion curves'. There is no limit to the number of defined relations in a configuration.

Movement trajectory curves

Each relation is defined by drawing a curve that represents the typical movement path:

• The curve is drawn from start point to end point

• Multiple points can be used to define complex trajectories

• Should follow the actual vehicle movement patterns in the video

Automatic direction classification

Each curve is automatically evaluated for the direction of motion relative to the curve start point:

Direction	Description
Straight	Movement continues in the same direction
Left	Movement turns to the left
Right	Movement turns to the right
Turning around	U-turn or reversal of direction

You can change this direction manually in the relation properties.

Relation states

Each relation can be enabled or disabled for counting and reporting purposes:

ON - Counted relations

• Vehicles from this relation are included in the result sheet

• Displayed with colored trajectory lines

• Contribute to traffic statistics and reports

OFF - Excluded relations

• Vehicles from this relationship are not included in the results

• Displayed in white color with strikethrough

• Useful for filtering out unwanted traffic patterns

Vehicles that are not included in the results in the spreadsheet are displayed in white with a strikethrough.

Relation grouping and aggregation

Relations can be grouped together for aggregated analysis:

Grouping by ID

Each relation can be aggregated with another relation as long as they have the same id. This allows:

• Multiple lanes of the same movement to be counted together

• Complex intersection movements to be simplified

• Flexible report generation based on traffic flow groups

Entrances and flows

The system automatically creates scene entrances and exists based on the defined relations. This allows for detailed flow analysis and cartogram generation:

• Entrance points (E1, E2, E3, ...) - starting points of relations

• Exit points (X1, X2, X3, ...) - ending points of relations

How are vehicles assigned to relations?

The assignment process uses trajectory similarity matching:

1. Tracker trajectory - Each moving object creates its own trajectory during tracking

2. Movement completion - After the movement of the object is completed, the trajectory is analyzed

3. Comparison - The trajectory is compared with the trajectory of each defined relation

4. Best match - The relation with the greatest similarity is considered the object's relation

5. Guaranteed assignment - The system always assigns some relation (there is no possibility for an object without relation)

Default relations - fallback when nothing is defined

When no relations are configured, the system creates default relations:

Relation ID	Name	Direction	Description
L	L	Bottom to Top	Left lane (vehicles moving up)
P	P	Top to Bottom	Right lane (vehicles moving down)

These defaults are created by the system and provide basic traffic counting functionality.