tracklet

A tracklet is a short, contiguous segment of a trajectory, typically representing the observed positions of an object over a limited period of time. In the context of object tracking, a longer trajectory is often broken down into multiple tracklets. This fragmentation can occur due to various reasons, such as temporary occlusions, missed detections, or the use of different tracking algorithms over different time intervals. The primary goal in many tracking systems is to associate these individual tracklets together to form a complete, consistent trajectory for each object.

The process of associating tracklets is known as tracklet association or tracklet linking. This involves comparing the characteristics of different tracklets, such as their positions, velocities, appearance, and predicted future states, to determine if they likely belong to the same object. Various algorithms exist for tracklet association, often employing techniques like Kalman filters for state prediction and Bayesian filtering or assignment algorithms for matching.

Tracklets are a fundamental concept in multi-object tracking, especially in scenarios with many objects, complex interactions, and challenging environmental conditions. By breaking down long trajectories into manageable tracklets, tracking systems can improve robustness and efficiency. For example, a tracker might initiate a new tracklet when a detection is made and attempt to associate it with existing tracklets. If successful, the tracklet is extended. If not, it might be considered a new object or a spurious detection. The ability to effectively manage and associate tracklets is crucial for achieving accurate and continuous object tracking.