基于AIS数据的受限水域船舶领域计算方法

为获取受限水域船舶领域, 提出一种利用海量AIS数据建立模型的方法。选取目标船舶的AIS数据, 将其附近水域网格化, 考虑了船舶尺寸, 计算了他船船体出现在每一个网格中的频数, 提取单船网格频数图, 将同一类型的目标船舶网格频数图叠加, 形成了特定类型船舶的网格频数图。将网格频数图按频数填充颜色, 可清晰地显示船舶领域的形状, 利用断面分析测量船舶领域长度。选用上海港南槽水域的AIS数据对方法进行验证, 统计了60~79、80~99、100~119、120~139、140~159m共5类不同长度船舶的船舶领域。分析结果表明: 由于考虑了船舶尺寸, 5类船舶的领域在长轴方向较船首向存在向左舷偏转的夹角, 角度分别为3.37°、9.46°、17.53°、10.78°、8.13°; 船舶领域长度与船舶长度的比值依次递减, 比值分别为6.00、5.80、5.67、5.43、5.13。可见受限水域内船舶领域形状为不规则椭圆, 且船舶领域长度与船舶长度的比值并非为定值。

Computation method of ship domains in restricted waters based on AIS data

In order to obtain the ship domains in restricted waters, a method was proposed by using large volume of AIS data.The AIS data of target ships were selected, and the waters nearby target ships were gridded.The occupy frequencies of other ships in each grid were calculated, and the grid frequency graph of single ship was extracted.The ship sizes were considered in the calculation process.Through overlying all grid frequency graphs of target ships with certain length, the grid frequency graph of specific ship was achieved.The grids in the grid frequency graphs were filled with colors according to different frequencies, then the shape of specific ship domain was observed clearly.Through fracturing and measuring the surface of ship domain, the length of ship domain was acquired.The proposed method was verified by using the AIS data from ships navigating in Nancao Restricted Waters of Shanghai Port.The domains of ships with the lengths of 60-79, 80-99, 100-119, 120-139, 140-159 m were calculated.Analysis result indicates that since the ship sizes are taking into consideration, the direction of ship domain's long axis has a portside deflection angle to heading, the angles are 3.37°, 9.46°, 17.53°, 10.78°, 8.13°respectively for the five types of ships.The length ratios of ship domain to ship decrease with the increase of ship length, and the ratios are 6.00, 5.80, 5.67, 5.43and5.13 respectively for the five types of ships.So the shape of ship domain in restricted waters is irregular ellipse, and the length ratio of ship domain to ship is not constant.