Extension of spatial metadata for navigating distributed spatial data

Navigating distributed spatial data have been the keystone of distributed GIS. Using spatial metadata is an effective method to locate and access spatial data. In this paper, based on the existing spatial metadata standards, a hierarchical spatial metadata database framework is presented. The framework is extended to describe the distribution of spatial databases, the relations among different spatial databases in network and how to support the fast navigation to spatial data. The framework consists of Global spatial metadata database (Global SMDB), District spatial metadata database (District SMDB) and General spatial metadata database (General SMDB), which can efficiently organize and manage distributed spatial data in network. Spatial data can be navigated quickly with support of the framework.