Tracker Barriers are virtual boundaries used by the tracking engine to prevent object tracks from being associated, re-identified, or merged across physically separated areas of the scene.
They are intended for locations where a real-world barrier makes movement between adjacent areas impossible, such as highway medians, guardrails, fences, noise walls, bridge edges, or glass barriers. Tracker Barriers are particularly useful in distant or shallow camera views, scenes with static occlusions, and other situations where tracking conditions are challenging.
Figure: Physical barriers make it realistically impossible for a trajectory to be tracked across them.
Since FLOW 2.3, Tracker Barriers can be configured in: Analytics Settings → Trajectory Processing → Tracker Barriers. Enable the feature and draw one or more barrier poly-lines along the physical separators visible in the scene.
Figure: Analytics settings -> Tracker barriers.
When an object becomes temporarily lost due to occlusion, perspective distortion, or limited image detail, the tracker may attempt to reconnect the trajectory using another nearby detection. Tracker Barriers prevent incorrect associations across these physical barriers. If such a situation occurs, a new trajectory ID is assigned instead.
For best results:
Align barriers with the ground projection of the physical barrier.
For narrow barriers, draw the poly-line through the center of the barrier.
Extend barriers through the area where incorrect associations may occur.
Barrier placement along road edges is usually unnecessary unless adjacent traffic could cause track mis-association.