2004
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
with own GIS node, while at other times the catalog will include connections to data streaming services, access to map
ort a data and services at many other GIS sites. Access to such a services, and data downloads in numerous desired formats.
lation clearinghouse node could be open on the World Wide Web,
ntent. while at other times it can be restricted and secure for a select Catalog portals require a complete information system for
cords audience. The NSDI, or National Spatial Data Infrastructure, geography, tools for data import and export, tools to validate
tions, is a concept developed by the United States federal data, tools to serve catalogs and data, search and discovery
many government and other state and local governments. The tools, tools to explore and use data, and tools to build and
s not Global Spatial Data Infrastructure (GSDI) is a nonprofit manage GIS data. A GIS metadata catalog plays the same
ation. organization composed of individuals, industries, and more role as a card catalog in a library (ESRI. March 2003). The
itions than 50 countries whose mission is to support ready global card catalog in a library has a record for each holding. All
n the access to geographic information. The NSDI and GSDI catalog records are compiled into one comprehensive catalog
promote the vision of a framework for GIS users to openly and indexed by author, subject, and title (and other
share geographic information and to collaborate on data keywords) so that the catalog can be searched. In a GIS, each
development (ESRI. March 2003). The vision of a National dataset has a metadata document. The concept behind a GIS
Spatial Data Infrastructure is based on GIS users openly catalog portal is that these metadata documents are collected
sharing key sets of GIS information and the ability of users to into a comprehensive metadata catalog that can be indexed
tional search for and discover information sets across the World by various means, such as by geographic location. Usually
Wide Web. Users should also be able to access datasets GIS experts intend more detailed metdata and General Public
through a variety of mechanisms—for example, via intend minimal metadata.
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Figure 2 : Metadata Completeness (Gerco Hoogeweg.2004 ) .
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so The catalog portal can then be searched to find candidate organization of the library as a system, such as the
& datasets for use. Just as in a library search, each metadata organization of its shelves. Similarly, a GIS network and its
ata record in a GIS catalog portal can be viewed. Optionally, catalog portals can be thought of as the organizing
C, users can connect to and explore the actual dataset to make a framework for a multiorganization GIS (e.g., a state or
decision about its potential use. This is a critical function national GIS). Each GIS requires a catalog that documents its
necessary for advanced GIS applications. In addition, the GIS data holdings and provides fast access to them. The goal of
Metadata Catalog can be thought of as the organizing metadata must be to create consistent documentation for
framework for a GIS just as the card catalog reflects the these holdings so that searches work across GIS systems.
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dress | [- X|ajizi0|@| Map-based searci Click the place you want to search and gu Lo step 2 s ;
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users. Figure 3 : GIS Catalaog (a): Catalog search, (b): Gazetteer, (c): Search result
user's
