Ship Space-Time AIS Trajectory Data Compression Method

Abstract

As the ship Automatic Identification system (Automatic Identification Systems, AIS) mandating the use of a large number of static and dynamic information related to the ship automatically through the shore-based or spaceborne terminal is passed to the maritime system and the shipping company, as an effective water traffic monitoring and management provides the necessary data to support. But because the ship is most of the time when navigating in high speed to or only minor adjustments, that receives a huge ship AIS trajectory data is invalid and redundant information, such a huge data increases the cost of computer memory, reduce the efficiency of data server calls. Therefore, it is important to study how to compress invalid and redundant information based on the main structural features of the AIS trajectory. This paper addresses the problem of many invalid and redundant information generated by Automatic Identification Systems (AIS), and conducts a study to effectively compress invalid and redundant information while preserving the main structural features of ship AIS trajectories. The main research work of this paper is to construct a compression method of ship space-time AIS trajectory data based on Douglas-Peucker (DP) algorithm and select the multiple thresholds to compress the upbound and down-bound ship AIS trajectories respectively. The DTW algorithm is used to evaluate the compression effect, and obtain the optimal compression threshold. Experimental results show that DP algorithm can efficiently compress ship AIS track data and retain pivotal feature points.