Gml-based Gis Data Interoperability Research And Design

Nowadays network contains amounts of geospatial information resources that are stored in many formats and maintained by myriad individuals and organizations. Interoperability of these resources has become a critical issue. However, traditional methods, i.e. data format exchange and data direct access, have many limits in effective data sharing, and consequently present serious problems such as false topology conversion and time-consuming, complicated file-level process, especially the lack of flexible operations on varied spatial objects. WebGIS, which rises recently, providing an effective way for various GIS platform to publish the layer level geographic information flexibly on the Internet, usually supports confined interoperability based on the same software platform, as causes so-called information isolated island problem. On the other hand, because of lacking common complied GIS data description and operation model, interoperability of heterogeneous data from different resources is still a major challenge.ISO/TC211 and OGC (Open Geospatial Consortium) are two international organizations dedicating to the standardization of GIS-related issues. By appropriately introducing various related standards, we proposed a general GIS data description schema that encompasses both the GML-based geographic data and metadata. The schema includes single geographic feature description and geographic feature collection description, aiding interoperability of heterogeneous data in a more efficient and flexible way. After the detailed discussion, an interoperability GIS model is then presented according to the proposed schema. The model is composed of three-tier architecture: client, server and resources. The server tier plays the key role and is discussed in detail. It contains the modules of WFS, WMS, WCTS and OGC Filter. Considering the heterogeneous resources, a GML translator is also introduced to convert non-GML data to the GML encoded. The client tier retrieves web maps and GML based feature-level geographic information based on the proposed schema, which actually ensures the correctness and integrity of GIS interoperability.