Mapping Ship Locations and Sensor Data in Near Real Time
By Tiffany Vance, Jason Fabritz, and Dennis Shields, NOAA
Editor's note: The National Oceanic and Atmospheric Administration (NOAA), through the Office of Oceanic and Atmospheric Research (OAR), conducts research and gathers data on the oceans, atmosphere, space, and sun. As part of these research activities, OAR has developed innovative technologies and observing systems. The Pacific Marine Environmental Laboratory (PMEL), one of OAR's 12 internal research laboratories, carries out interdisciplinary scientific investigations in oceanography and atmospheric science aboard NOAA research vessels. The authors, as part of their work at NOAA, developed an ArcIMS application that maps the current location of various NOAA ships in near real time and provides information on weather and ocean conditions. This application won a NOAATECH 2002 award.
NOAA maintains a fleet of research vessels in both the Pacific and Atlantic Oceans. These vessels conduct various types of research and are used by multiple projects. Knowing where the vessels are working and the environmental conditions they are experiencing is vital not only for scientists using the vessels but also for the family and friends of the ships' crews. An ArcIMS-based Web site called ShipTracker displays scientific data and general information about ship locations and working conditions. Creating this site required developing tools that would provide near real-time display of tracked items (i.e., ships) in a GIS that could be used for analysis and information dissemination through the rapid generation of Web pages.
The ShipTracker Web site uses ArcIMS to generate the maps displayed on the site in near real time. Messages are sent automatically by the Shipboard Computer System (SCS) on NOAA vessels. The messages reach a server at PMEL via e-mail. These messages are processed and the data uploaded into a central database. Periodically the process examines the database for new information and regenerates the images displayed on the Web site, if necessary. The ships' locations are presented on an acetate layer overlaying an image service showing bathymetric and topographic data. The service, implemented using Java, communicates with the ArcIMS map service through HTTP requests written in eXtensible Markup Language (XML). The Web site itself is a combination of static HTML pages, images updated by the map service, and JavaServer Pages (JSP) for the interactive portions of the site.
The ShipTracker page displays the location of all the ships in the fleet and allows a user to select a specific ship by name or an area of the ocean by latitude and longitude. The user can also click on the map to select a ship and access the ship-specific page. The summary page for a specific ship shows a detailed map of the ship's location and recent trackline. The width and color of the trackline decreases with older observations, making it easy to see where the ship has been. The page also displays a summary of the current environmental conditions as measured by the ship's instruments. This summary can be changed depending on the needs of the research project currently using the ship. Project-specific data could also be added to the data stream sent in by the ship.
Shipboard Computing
SCS software, developed by the Office of Marine and Aviation Operations (OMAO) specifically for the NOAA fleet, is a data acquisition and processing system designed for oceanographic and fisheries applications. It is networked throughout the ship and is capable of sending data displays to remote stations (i.e., SCS NT clients) on the ship. In addition, ASCII data strings can be sent via RS-232 cable or over the Ethernet. SCS can be configured to generate a current conditions message giving values of selected sensors at a user-selected interval. The data is sent to shore in an e-mail message. The ship transmits e-mail to shore two or three times a day via Inmarsat (a worldwide satellite communications network sponsored by the International Mobile Satellite Organization) or by cell phone. E-mail messages are packaged and sent as a single file. The messages are unpacked on shore and transmitted to the addressees. Another standard system, SEAS, provides a backup system for delivering data about current conditions.
Shore-Based Processing
Once data on current conditions is transmitted, it is added to a MySQL database configured to store data from the ships and housed on a UNIX machine. Configuration parameters for the image service are also stored there, and a Java-based GUI front end is used for administration. MySQL was chosen for its ease of configuration and its no cost (i.e., open source software). Duplicate and spurious entries are detected in the loading process.
Internet Map Server
ArcIMS 3.1 running on a UNIX box creates the maps on the Web pages. The basemaps for the image service are generated from topography/bathymetry data stored as shapefiles, and ship locations are added as an acetate overlay. The size of the maps is based on the location of the ships. The use of an acetate layer allows generation of a dynamic view that can be easily updated each time a ship reports new positional information.
XML and ArcXML are used for creating and returning map images. The images are regenerated each time new data is received. Images created include an overview image and ship-specific zoomed-in images. The administration tools are used to set update frequency, file storage locations, and other parameters. Similar to the GUI front end for database configuration, the server administration is also Java based. The Web server and Web pages are a two-tier system that connects to the MySQL database to retrieve ship observations. The Web page selects the ship for display based on user input. The Web pages are hosted on an Apache Tomcat server, and the pages themselves are a mixture of JSP pages, static HTML pages, and images created by the Map Server.
Enhancements
Planned enhancements to ShipTracker include the ability to select the time period for the display of historical data, zoom to the area displayed, and add features such as the ship's anticipated trackline (from a shapefile). The methods developed for the ShipTracker pages are being applied to other tracked entities such as marine buoys and instrumented marine mammals.
For more information about the Pacific Marine Environmental Laboratory, please visit the PMEL home page at www.pmel.noaa.gov. For more information about the NOAA fleet and the Office of Marine and Aviation Operations, please visit the OMAO home page at www.moc.noaa.gov.
Acknowledgments
Many individuals have contributed ideas, effort, and data to this project. They include the various electronics technicians onboard the ships who have kept the daily reports arriving, Nazila Merati for Web page design advice/technical support, and OMAO management for continuing support of the project. Everyone's contributions have been vital to the project. This project has been funded in part by a grant from the NOAA High Performance Computing and Communication-Visualization Initiative (www.hpcc.noaa.gov/visual.html).
About the Primary Author
Tiffany C. Vance, Computer Specialist
National Oceanic and Atmospheric Administration
Formerly with: Pacific Marine Environmental Laboratory
Now with: Alaska Fisheries Science Center
7600 Sand Point Way NE
Seattle, Washington 98115
Tel.: 206-526-6767
E-mail: Tiffany.C.Vance@noaa.gov
|
