VCA - Object trails

The trail shows the history of where the object has been.
Depending on the calibration the trail can be drawn from the centroid or the mid-bottom point of the object.
(See Advanced Settings for more information).
The trail is important for determining how a rule is triggered.
The intersection of the trail point with a zone or line determines whether a rule is triggered or not.
The following image illustrates this point: the blue vehicle's trail intersects with the detection zone and is rendered in red.
Conversely, while the white vehicle intersects the detection zone, its trail does not (yet) intersect and hence it has not triggered the rule and is rendered in yellow.