Maps or not? A new insight of the map interface to the open and distributed geospatial web service environment

One major merit of the OpenGIS technology is users can easily acquire remote and heterogeneous geographic data and effortlessly use them in their applications. As convenient as it may look, unpredictable risk may hide in such decision making processes while users may never notice. Unlike traditional maps that must be made following rigorous mapping specifications, the dynamically generated content of map interface often lacks cartographic consideration regarding the various detail, time, completeness, position accuracy of acquired geospatial data, therefore should not be literately regarded as a "map". Nonetheless, most users, naïve or professional, still intuitively and incautiously use them as a map. We argued that users must be able to intelligently acknowledge the difference among acquired data before they can make any further decisions. By first analyzing the prerequisite and fundamental characteristics of maps, we proposed a metadata framework that can be applied to the distributed geospatial data to provide necessary information regarding map illustration. We then develop an application program that can correctly interpret acquired metadata information based on built-in cartographic knowledge to determine if the map interface content can be regarded as a map and present visual aids of analyzed results based on cartographic visual variables. The encoding of the distributed geospatial data and metadata conforms to the ISO 19115 and ISO19136 (GML) standards to ensure the proposed framework can be successfully applied to the future WFS-based distribution environment. The result demonstrated the proposed strategy can "visually" improve the correct interpretation of map interface content. As more and more data accessible via SOA and NSDI in the future, a new paradigm of map interface should be developed for any application program that wishes to take advantages of such abundant geospatial resources.