AAIR Project No PL 94-2392

META DATA

Metadata Information

Definition

Metadata is data about the content, quality and condition, and other characteristics of data.

METADATA = Identification Information
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Data Quality Information
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Spatial Data Organization Information
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Spatial Reference Information
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Entity and Attribute Information
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Distribution Information
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Metadata Reference Information

Four Roles of Metadata:

Availability - what data exist for a geographic location

Fitness for Use - whether a set of data meet a specific need

Access - what are needed to acquire an identified set of data

Transfer - data needed to process and use a set of data

Importance

Meta data is fundamentally important because digital data comes as a file of coordinates and code which, unlike paper maps, will not include a legend to explain information about the scale, copyright, attribute coding, map projection and the organisation responsible for producing the map.

The provision of meta data pre-empts time-consuming problems for both the data user and the data provider caused by not having enough information to use a data set effectively. It is crucial in the exchange and integration of data.

Digital data may be misused if there is no information about the scale, error and accuracy of the original map from which the digital data was derived. If the map is in a particular coordinate system and the details of the map projection and the coordinate system were not recorded when the map was digitised, it will be impossible to accurately transform the information to reconcile the map with digital data from other origins. The original map containing these details may no longer be available so it is important to record the information during the original data capture. If a map were digitised using AUTOCAD and exported in DXF format, it may be difficult to read this format using ARC/INFO if, for example, the version of AUTOCAD being used is particularly old and the version of ARC/INFO very recent. If the software and its version are recorded at the time of digitising, it may be possible for a user to get a copy of the appropriate version of the software to read the data. However, if the software and version were not recorded at the time of digitising, the data may be unreadable.

As digital media are more widely used, meta data will become a necessary standard, for data exchange and for cataloging databases. Cataloging will enable data browsers to provide information about the origins, geographic extents and contents of large numbers of data sets available over the internet. This will mean fast and efficient location of data and will avoid the need to download large data sets which are then found to be inappropriate for a particular task.

Marianne Broadgate - m.broadgate@macaulay.ac.uk

Last modified: Thu Apr 25 11:32:46 BST 1996