Coverage data

In geographic information systems, a coverage is a mapping of one aspect of data in space. It represents a "domain" (the universe of extent) in terms of characteristics expressing a range of values. For example: a satellite image derived from remote sensing might record varying degrees of light pollution. Aerial photography, land cover data, and digital elevation models are all considered coverage data.

As a contrast to coverage data we find feature data, which concentrates more on the numerous characteristics of a spot and less on its spatial surrounds.

GIS Format

"Coverage" is the term typically applied to the legacy ARC/INFO feature data format developed by Esri. The ARC/INFO coverage data model was a revolutionary concept, by storing graphical information with arc-node topology ("ARC") with features linked to attributes stored an simple, single-user RDBMS ("INFO"). In ARC/INFO, the BUILD and CLEAN commands and overlay tools such as INTERSECT and IDENTITY construct and maintain planar arc-node topology. The coverage data model is used to explicitly store this topological information useful for spatial analysis, for example, each polygon "knows" which segments of its perimeter are shared with adjacent polygons. Due to the lack of processing power in computing and limited RDBMS technology avaialable at the time of its development, the Coverage model employs indexed binary files to store spatial data separately from attribute data. In contrast, many modern GIS systems use an RDBMS to store both spatial and attribute data..

The coverage data model is implemented in a file system as a folder ("workspace") containing a) an "info" folder to store data tables and b) one or more coverage folders.

Web Coverage Service

Coverage may also refer to WCS, a protocol for delivering coverage data.