船舶轨迹数据的Geodatabase管理方法

 船舶轨迹的自动观测记录已进入了大数据时代,其呈爆炸式增长的趋势给传统的轨迹数据管理方式带来了巨大挑战。本文针对通用船舶自动识别系统(AIS)岸基网络中船舶轨迹数据上传频率高,数据量大,覆盖范围广的特点,首先,分析了当前常见船舶轨迹数据存储方法存在的缺陷,概括了船舶轨迹数据的特征并对其进行抽象建模,然后,在时空立方体模型的基础上,提出了从抽样时刻、步进时段到每日航次的三层组织框架的建模思想,设计了Geodatabase的网格化三级时空立方体模型,实现了海洋运输船舶轨迹观测记录的Geodatabase管理方法。通过我国AIS岸基网络(温州-汕头)单日观测数据的实例验证,表明该模型存储及时空查询性能良好,且具有轨迹数据存储、查询和空间分析一体化管理的独特优势。

Study on Vessel Trajectories Database Manage System Based on Geodatabase

In order to monitor real-time vessel information to improve navigation safety, China＇s Maritime Safety Administration （MSA） has built the world＇s biggest Automatic Identification System （AIS） shore-based network, in which data such as ship position, name, purpose, course and speed are automatic col-lected 24 hours per day primarily in Chinese coastal waters. As a result, China is approaching the era of big data storage of vessel trajectories, which has brought great challenges to traditional moving objects da- ta management systems. Beyond their basic functions of loading and displaying vessels＇ position records, an ideal vessel trajectories database should bring user more advance functions of analysis of ship tracking records by supporting spatio-temporal query and prediction of vessel movement. In this paper, we start with the character of vessel movement and abstract the data model of vessel trajectories according to state-of-the-art technology of moving objects databases. Due to the characteristics of vessel trajectories data, such as changing frequently, wide cover range and mass datum, it is argued that current methods of traj-ectories storage still deserve much more research and improvements, especially for spatio-temporal query and geoprocessing support methods. Considering the role of time perspective, vessel trajectories are man- aged by three kind of time unit （sampling instant, stepping period and 24 hours） so as to built a three-lev- el organizational framework. By compressing the volume of data and matching original vessel tracking message into spatio-temporal cube unit the retrieval efficiency increases significantly. It was also described how to streamline the acquisition, loading, filtering, display and analysis of raw AIS log files. This meth-od is applied in handling daily mass vessel tracking records which are covering western Taiwan Strait. Ex- periences show that this model satisfied the requirements of application. The storage is reduced and the performance of spatio-temporal query is improved. Using ArcGIS platform of Geodatabase module, vessel trajectories＇ initial data model is easy to revised, expanded and integrated with various relational base-map data. Furthermore, it is convenient to apply variable ArcGIS geoprocessing tools to obtain customize de-mand, such as daily hot spot activities of fishing vessel. By generating these synthesized products our so-lutions would support the ocean planning community to better understand marine transportation patterns and potential use conflicts between vessels and other activities.