Establishing a Real-time Vessel Monitoring Web GIS
The International Maritime Organization (IMO) has concluded the Safety of Life at Sea (SOLAS) Agreement, mandating the installation of Automatic Identification System (AIS) on international voyaging ships with 300 or more gross tonnage (GT), and all passenger ships regardless of size.
Since the AIS receive and return signals in dynamic coding format, the competent authorities can get the MMSI number, the rate of turning (ROT), and the coordinates of each vessel, allowing them to recognize, track, and send messages to the vessels in a specific area. Therefore, with the help of AIS, it becomes more efficient to monitor marine pollution, secure lives and property of the crew aboard, ensure the navigation safety, as well as regulate the activities on the sea.
To make the AIS data apply to different circumstances, National Kaohsiung Marine University (NKMU) build a web GIS, which is capable of saving and analyzing data in the database, and then shows the results on the web map in near real-time. Users can grasp the information of the current positions of vessels and their shipping routes in Port of Kaohsiung. Also, other static information like the nationality, type, power supply, and size of the vessel will all be shown in the pop-up window.
The objective of establishing this web GIS is to display the geographic information of AIS data on the map, allowing the competent authorities to track down the status of each ship. The main project content is listed as follows:
- Positioning and Data Integration:
First, import and save the AIS data. Then, extract the needed ones and show them on the map built by GIS server. The current directions of sailing are represented by where the icons point at.
- Loading TGOS Basemap:
After integrating the positioning data, overlay them with TGOS, the complete online map established by Ministry of the Interior, as basemap. This would enable users to understand the locations of all vessels and the spatial relations in the appointed region.
- Setting up the Attribute Querying:
The attribute querying function should be established on a map so that users can learn more information easily by clicking the icon of a vessel. The pop-up window will show the related information, such as vessel ID, sailing condition, velocity, power supply, etc.
- Shipping Route:
The shipping route of each vessel can be displayed on the map. Users can decide if they want to see the detailed course of each ship by switching the settings on the interface.
- Displaying over Different Time:
Users can understand the sailing condition of a particular vessel on different dates by splitting the display window in half and setting up the time of display on each window.
First, acquire the instant data from AIS and decode them by a C# program. Then, save the data in a MySQL database and convert them into the data format supported by SuperGIS Server.
Use SuperGIS Server 3.3 as the basis for web GIS development. Because the positioning data sent back by AIS is in longitude and latitude, the project team chooses OSM as basemap and the coordinate system as EPSG 3857. Then, use IIS to publish it as a website.
Display vessels dynamically:
Through this Web GIS, users can visualize the locations of ships as they are displayed in near real-time. Users are also allowed to switch among different online basemaps.
Fig. 1 Using OSM Dark as basemap
Fig. 2 Using OSM Light as basemap
Fig. 3 Using TGOS as basemap
Pop-up windows for attribute querying:
Click the icon of a particular vessel and then you can get the correct information about this boat quickly, such as vessel ID, type, the direction of sailing, etc
Fig. 4 Pop-up windows for attribute querying
Turn on the shipping route displaying:
After turning on this function, click the vessel you want, and its historical sailing paths will be shown on the map.
Fig. 5 Displaying shipping route
Display over different time:
Users can set up different dates on split windows to know the sailing status of a particular vessel in different periods.
Fig. 6 Displaying the tracks over different time
NKMU uses SuperGIS Server to develop customized applications: This Vessel Monitoring System has successfully decoded the data from AIS and displayed it on a Web GIS to visualize the locations of vessels. Users can click the icon of a ship to instantly query the information, such as vessel ID and shipping routes in the database. For the competent authorities like Coast Guard Administration, the system will be a great help for vessel monitoring. Also, the capability of displaying over different time will allow the authorities to trace back to the historical sailing paths if a vessel is involved in illegal activities, ensuring the maritime security.