Spatial Data Infrastructures

Characteristics of Spatial Data

Spatial data can be used for many different purposes due to their special characteristics. Like other types of data, spatial data can be encoded digitally and transported via the Internet. But also, in many cases, they can be displayed graphically, making the information easier to interpret and understand. However, there are other characteristics of spatial data that need to be managed before one makes use of them. Many organizations capture spatial data but often in quite different ways and for many purposes. A single organization may capture spatial data for a limited part of the world—for example, a national mapping agency; therefore, spatial data from many organizations must be combined to ensure worldwide coverage. Furthermore, often these spatial data have a short shelf life and therefore will become outdated in a short period.

Due to these special characteristics of spatial data, an efficient integration, transport, and distribution mechanism is crucial to enhance their overall usage. The geospatial information sector identified this potential very early and pushed the development of spatial data infrastructures. SDIs are one of the first large applications of information infrastructures based on Web services.

History

In the early 1990s, these spatial data characteristics resulted in many incompatible solutions.

Early developments focused on the creation of a standard and vendor-neutral data model to encode and exchange spatial data. These efforts were channeled via the founding of the OpenGIS in 1994, which is known today as the Open Geospatial Consortium (OGC). Major milestones since then were the formulation of the U.S. national SDI by the Federal Geographic Data Committee and the first Global SDI conference, GSDI 1, in Bonn, Germany, in 1996. Parallel developments within the World Wide Web and the Internet added a new capability to call remote functions, which are known today as Web services. In 2000, the popular Web Mapping Service specification was released by the OGC. As a result, many local, regional, national, and supranational SDI initiatives were founded. In 2007, the European Union (EU) enacted into law the INSPIRE (Infrastructure for Spatial Data in Europe) directive, together with a long-term road-map for the implementation of this law running until 2015 and beyond. The law defines 34 spatial data themes, some for geospatial reference data, and other themes needed to support health, agricultural, urban, and environmental applications. It requires public bodies within each of the 27 EU member states to provide data relating to spatial data themes as a set of services for use by institutions and organizations in the EU.

As the development of SDIs is a work in progress, this entry can describe only the current state of the art. Many of the key concepts behind SDIs are stable, while others are evolving.

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