WEB COVERAGE SERVICE (WCS)


The Web Coverage Service (WCS) is defined by Open Geospatial Consortium (OGC), to obtain geographic spatial data with coverages of geographic spatial information. It also displays features of spatial changes, so that, they are representes graphically or as an input data for scientific models.

The main difference with the WMS is that WCS provides data with detailed description, so that, data can be explained or compared, not only esthetically.

WCS also provides coverages which display time-space changes features to manage geographic spatial discontinuous entities.

The Aragon Goverment implements this service with GeoServer. At the moment, WCS serves the following information:

  • Digital Model Terrain(DTM): 5 m.
  • Digital Model Terrain (DTM): 200 m.
  • Map of Directions, raster coverage derived from the DTM 200 m.
  • Map of Slopes, raster coverage derived from DTM 200 m.

The standard defines three basic actions:
  1. GetCapabilities, It returns the formal description or metadata and the server coverage descriptions.
  2. DescribeCoverage, It returns an XML document with detailed description of the coverage.
  3. GetCoverage, It obtains a coverage in some compatible formats: GeoTIFF, TIFF, GIF, JPEG, ARCGRID. The queries are defined by users.

The URL formal description of the WCS provided by IDEAragon is the following:

  • GetCapabilities to the WCS of IDEAragon: http://idearagon.aragon.es/GeoserverWCS?service=WCS&request=getCapabilities

  • A WCS client allows download raster data. The server returns an image with all the information included. WCS in IDEAragon is integrated from web environments and pay software or freeware SIG clients. Below, some significant examples of requests to the service with a web browser:

    • Example of URL request DescribeCoverage, to the Map of Slopes.
    • Example of URL request GetCoverage, it returns a geotiff format file including the requested spatial area according to the DTM 200 m. coordinates.