Chan Weng Tat, Li Rongrong and Durairaju Kumaran Raju
Marine Information Technology Laboratory
Tropical Marine Science Institute
National University of Singapore
14 Kent Ridge Road, Singapore – 119223
Our ability to map and visualize spatial data has improved significantly with new developments in computer hardware and software technology. The present development is to effect access, distribution and update of spatially attributed data via web-based systems involving GIS and mapping technology. Interactive digital maps have also become the means by which users present their queries to databases and information stores.
This paper describes a web-based system for publishing marine environmental data. The system takes advantage of Internet mapping and web-services technology to publish data as maps. These maps are created dynamically and enable the visualization of a diverse and growing collection of environmental data on tropical marine waters assembled at the Tropical Marine Science Institute. Capabilities of the system include (1) visualization of environmental parameters on 2D maps; (2) visualization of location-specific depth-profiles of selected parameters; (3) time animation of grids of environmental parameters, and (4) preparation of digital elevation and cultural object data sets for 3D terrain visualization. The function and interaction between key components of the system are described to illustrate how the system works. The use of a mature map publishing engine greatly eased the development of these capabilities into a web-based system.
There were significant challenges in the development of such a system. The first was the organization of the data sets so that users could easily get the data they wanted without being burdened with cumbersome and non-intuitive procedures. A simple, hierarchical file system organization simplifies the maintenance of the file data-store but may be too restrictive or cumbersome for users when trying to locate data under conditions that had not anticipated. This prompted the development of a metadata schema to represent the concepts and attributes of the data sets in XML. The metadata catalog is used to index and retrieve data sets based on combining attribute specifications without regard to actual physical file locations. A second challenge was the diversity in the organization of the information in the data-sets and the formats in which this information was represented. Some key decisions were adopted with regards to the standardization of information representation and file formats; these had a significant influence in guiding code development and will facilitate future enhancements to the system.