sArticle A Dimensionality Reduction-Based Multi-Step Clustering Method for Robust Vessel Trajectory Analysis Huanhuan Li 1, Jingxian Liu 1,2, Ryan Wen Liu 1,*, Naixue Xiong 3,*, Kefeng Wu 4 and Tai-hoon Kim 5 1 Hubei Key Laboratory of Inland Shipping Technology, School of Navigation, Wuhan University of Technology, Wuhan 430063, China;
[email protected] (H.L.);
[email protected] (J.L.) 2 National Engineering Research Center for Water Transport Safety, Wuhan 430063, China 3 School of Mathematics and Computer Science, Northeastern State University, Tahlequah, OK 74464, USA 4 School of Automation, Huazhong University of Science and Technology, Wuhan 430074, China;
[email protected] 5 Department of Convergence Security, Sungshin Women’s University, 249-1 Dongseon-dong 3-ga, Seoul 136-742, Korea;
[email protected] * Correspondence:
[email protected] (R.W.L.);
[email protected] (N.X.); Tel.: +86-27-8658-7900 (R.W.L.); +1-404-645-4067 (N.X.) Received: 27 April 2017; Accepted: 1 August 2017; Published: 4 August 2017 Abstract: The Shipboard Automatic Identification System (AIS) is crucial for navigation safety and maritime surveillance, data mining and pattern analysis of AIS information have attracted considerable attention in terms of both basic research and practical applications. Clustering of spatio-temporal AIS trajectories can be used to identify abnormal patterns and mine customary route data for transportation safety. Thus, the capacities of navigation safety and maritime traffic monitoring could be enhanced correspondingly. However, trajectory clustering is often sensitive to undesirable outliers and is essentially more complex compared with traditional point clustering.