Web Coverage Service
The Open Geospatial Consortium Web Coverage Service Interface Standard (WCS) provides an interface allowing requests for geographical coverages across the web using platform-independent calls. The coverages are objects (or images) in a geographical area, whereas the WMS interface or online mapping portals like Google Maps return only an image, which end-users cannot edit or spatially analyze.
The OGC membership defined and maintains the WCS specification. GeoServer serves as the reference implementation of the standard.
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[edit] Overview
The basic Web Coverage Service allows querying and retrieval of coverages.
A WCS describes discovery, query, or data transformation operations. The client generates the request and posts it to a web feature server using HTTP. The web feature server then executes the request. The WCS specification uses HTTP as the distributed computing platform, although this is not a hard requirement.
There are two encodings defined for WCS operations:
- XML (amenable to HTTP POST/SOAP)
- Keyword-Value pairs (amenable to HTTP GET/Remote procedure call)
In the taxonomy of Web Services, WCS is best categorized as a non-RESTful RPC type service.
[edit] Data
Data may be available in several formats, such as DTED, GeoTIFF, HDF-EOS, or NITF.
Several types of data layers are supported:
- series of points, such as locations of samples
- regular grid of pixels or points, which might represent a photo
- set of segmented curves, often used for road paths
- set of Thiessen polygons, used to analyse spatially distributed data such as rainfall measurements
- triangulated irregular network (TIN), often used for terrain models
Ranges of information may be attached to locations, such as average wind speed or yield by crop type.
[edit] Software support for WCS
The Compliance and Interoperability Test Engine (CITE) is used to test reference implementations for OGC specs, including WCS. List of software that supports WCS as a client and/or server:
- GeoServer - reference implementation server (serve WCS)
- APOLLO - server and client[1]
- GDAL - client (read)[2]
- Geomatica Web Server Suite - client and server[3]
- GeoMedia - client (read WCS) and server (GeoMedia WebMap)
- gvSIG - client (read WCS)
- MapServer - server[4]
- ArcGIS Server - server and client[5]
- PYXIS WorldView - Client integrates multiple sources of data on a hexagonal discrete global grid [6]
- CARIS Spatial Fusion Enterprise - server and web client [7] - server
- Unidata TDS (THREDDS OPeNDAP data server) - server
[edit] See also
- Open Geospatial Consortium
- GeoServer
- gvSIG
- GDAL
- MapServer
- Web Map Service (WMS)
- Web Feature Service (WFS)
[edit] References
- ^ "ERDAS APOLLO". http://www.erdas.com/products/ERDASAPOLLO/ERDASAPOLLO/Details.aspx.
- ^ "WCS -- OGC Web Coverage Service". http://gdal.org/frmt_wcs.html.
- ^ "PCI Geomatics’ Web Coverage Server successfully passes compliancy testing". http://www.pcigeomatics.com/pressnews/2008_PCI_webtest.html.
- ^ "WCS Server". http://mapserver.org/ogc/wcs_server.html.
- ^ "ESRI ArcGIS Server". http://www.esri.com/software/arcgis/arcgisserver/index.html.
- ^ "PYXIS WorldView GeoWeb Browser". https://www.pyxisinnovation.com/.
- ^ "CARIS SFE web page". http://www.caris.com/products/sfe/.
[edit] External links
- OGC Web Coverage Service
- OpenGIS Web Coverage Service (WCS) Implementation Specification
- WCS implementations
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