Metadata and data catalogues

Geospatial data, or data tied to a location on the Earth, are critical to solving today’s complex environmental, economic, and social problems. The use of GIS technologies for analysing spatial problems has become pervasive and, in the process, has created a demand for vast amounts of digital geospatial data. To meet that demand, the data that describe the characteristics of geographical space must be current and of known quality. The data must be easily accessible and able to be integrated, generalised, and manipulated with understood or predictable results. Meeting all of these requirements is difficult today. Two coupled developments – the use of metadata and the provision of data catalogues – are helping to create an environment to accommodate today’s requirements for geospatial data. As technology provides faster and more efficient ways to transmit and process geographical data, data producers and users are realising the potential value of exchanging and sharing spatial data. The ability to use existing spatial data is important to organisations which are trying both to share data and to increase benefits from their data collections. This ability depends not only on being able to find data, but also on understanding the characteristics and quality of the data. Metadata, or data about data, provide information such as the characteristics of a dataset, its history, and the organisations to contact to obtain a copy of it (see also Goodchild and Longley, Chapter 40). Standardised metadata elements provide a means to document datasets within an organisation, to contribute to catalogues of data that help individuals find and use existing data, and to help users understand the contents of datasets that they receive from others. A collection of metadata records combined with data management and search tools forms a data catalogue. The architecture of these data catalogues can vary from tightly held internal data indexes to widely accessible distributed catalogues spread across the Internet. The catalogue function can go far beyond the basic listing of content. Extensions that allow for direct ordering or download of data, user comment or feedback, as well as requests for new data collections, are all possible. Metadata and data catalogues are thus the means by which data users can more economically find, share, and use geospatial data.