Online Mobility Tracking Against Evolving Maritime Trajectories
This hands-on material concerns research techniques that may be used for mobility tracking over trajectories of vessels monitored over a large maritime area. The focus is on maintaining summarized representations of such trajectories in online fashion based on surveillance data streams broadcast through Automatic Identification System (AIS) and concerning positions from a fleet of numerous vessels.
We provide source code of several generic, state-of-the-art trajectory simplification algorithms that can offer concise summaries of each trajectory as it evolves. Instead of retaining every incoming position, such methods drop any predictable positions along trajectory segments of normal motion characteristics with minimal loss in accuracy. Note that each algorithm specifies its own parametrization, which may require careful fine-tuning depending on the characteristics of the available AIS data.
This video simulates the simplified synopsis of a vessel trajectory sailing from the port of Thessaloniki, moving across the Aegean Sea, and finally reaching Rhodes. Note that this simplification algorithm also identifies critical points, i.e., it annotates each retained point in this synopsis with a particular characterization (stop, turn, slow motion, etc.) that captures important changes across the route in online fashion: