Web Coverage Service
Encyclopedia
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.
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:
In the taxonomy of Web Services, WCS is best categorized as a non-RESTful RPC type service.
, GeoTIFF
, HDF-EOS, or NITF
.
Several types of data layers are supported:
Ranges of information may be attached to locations, such as average wind speed or yield by crop type.
Open Geospatial Consortium
The Open Geospatial Consortium , an international voluntary consensus standards organization, originated in 1994. In the OGC, more than 400 commercial, governmental, nonprofit and research organizations worldwide collaborate in a consensus process encouraging development and implementation of open...
Web Coverage Service Interface Standard (WCS) provides an interface
Interface (computer science)
In the field of computer science, an interface is a tool and concept that refers to a point of interaction between components, and is applicable at the level of both hardware and software...
allowing requests for geographical
Geography
Geography is the science that studies the lands, features, inhabitants, and phenomena of Earth. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes...
coverages
Coverage data
In geographic information systems, a coverage is a mapping of one aspect of data in space. It represents a "domain" 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...
across the web
World Wide Web
The World Wide Web is a system of interlinked hypertext documents accessed via the Internet...
using platform-independent calls. The coverages are objects (or images) in a geographical area, whereas the WMS
Web Map Service
A Web Map Service is a standard protocol for serving georeferenced map images over the Internet that are generated by a map server using data from a GIS database...
interface or online mapping portals like Google Maps
Google Maps
Google Maps is a web mapping service application and technology provided by Google, free , that powers many map-based services, including the Google Maps website, Google Ride Finder, Google Transit, and maps embedded on third-party websites via the Google Maps API...
return only an image, which end-users cannot edit or spatially analyze.
The OGC membership defined and maintains the WCS specification. GeoServer
GeoServer
In computing, GeoServer - an open-source server written in Java - allows users to share and edit geospatial data. Designed for interoperability, it publishes data from any major spatial data source using open standards...
serves as the reference implementation of the standard.
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:
- XMLXMLExtensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
(amenable to HTTP POST/SOAPSOAPSOAP, originally defined as Simple Object Access Protocol, is a protocol specification for exchanging structured information in the implementation of Web Services in computer networks...
) - Keyword-Value pairs (amenable to HTTP GET/Remote procedure callRemote procedure callIn computer science, a remote procedure call is an inter-process communication that allows a computer program to cause a subroutine or procedure to execute in another address space without the programmer explicitly coding the details for this remote interaction...
)
In the taxonomy of Web Services, WCS is best categorized as a non-RESTful RPC type service.
Data
Data may be available in several formats, such as DTEDDTED
DTED is a standard of digital datasets which consists of a matrix of terrain elevation values. This standard was originally developed in the 1970s to support aircraft radar simulation and prediction....
, GeoTIFF
GeoTIFF
GeoTIFF is a public domain metadata standard which allows georeferencing information to be embedded within a TIFF file. The potential additional information includes map projection, coordinate systems, ellipsoids, datums, and everything else necessary to establish the exact spatial reference for...
, HDF-EOS, or NITF
National Imagery Transmission Format
The National Imagery Transmission Format Standard is a U.S. Department of Defense and Federal Intelligence Community suite of standards for the exchange, storage, and transmission of digital-imagery products and image-related products.DoD policy is that other image formats can be used internally...
.
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.
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:- GeoServerGeoServerIn computing, GeoServer - an open-source server written in Java - allows users to share and edit geospatial data. Designed for interoperability, it publishes data from any major spatial data source using open standards...
- reference implementation server (serve WCS) - APOLLO - server and client
- GDALGDALGDAL is a library for reading and writing raster geospatial data formats, and is released under the permissive X/MIT style free software license by the Open Source Geospatial Foundation. As a library, it presents a single abstract data model to the calling application for all supported formats...
- client (read) - Geomatica Web Server Suite - client and server
- GeoMediaGeoMediaGeoMedia is the technology, suite of software components in Intergraph Corporation's geographic information system and family of software products that include: GeoMedia Objects, GeoMedia Viewer , GeoMedia, GeoMedia Professional, GeoMedia WebMap, GeoMedia WebMap Professional and others...
- client (read WCS) and server (GeoMedia WebMap) - gvSIGGvSIGgvSIG is a geographic information system , that is, a desktop application designed for capturing, storing, handling, analyzing and deploying any kind of referenced geographic information in order to solve complex management and planning problems. gvSIG is known for having a user-friendly interface,...
- client (read WCS) - MapServerMapServerMapServer is an open source development environment for building spatially-enabled internet applications. It can run as a CGI program or via MapScript which supports several programming languages . MapServer was developed by the University of Minnesota — so, it is often and more specifically...
- server - ArcGIS Server - server and client
- PYXIS WorldView - Client integrates multiple sources of data on a hexagonal discrete global grid
- CARIS Spatial Fusion EnterpriseCARISCARIS is a software company that develops and supports geomatics software for land and marine applications.The company was founded in Fredericton, New Brunswick, Canada in 1979 as Universal Systems Ltd...
- server and web client - server - Unidata TDS (THREDDS OPeNDAPOPeNDAPOPeNDAP, an acronym for "Open-source Project for a Network Data Access Protocol", is a data transport architecture and protocol widely used by earth scientists. The protocol is based on HTTP and the current specification is . OPeNDAP includes standards for encapsulating structured data, annotating...
data server) - server
See also
- Open Geospatial ConsortiumOpen Geospatial ConsortiumThe Open Geospatial Consortium , an international voluntary consensus standards organization, originated in 1994. In the OGC, more than 400 commercial, governmental, nonprofit and research organizations worldwide collaborate in a consensus process encouraging development and implementation of open...
- GeoServerGeoServerIn computing, GeoServer - an open-source server written in Java - allows users to share and edit geospatial data. Designed for interoperability, it publishes data from any major spatial data source using open standards...
- gvSIGGvSIGgvSIG is a geographic information system , that is, a desktop application designed for capturing, storing, handling, analyzing and deploying any kind of referenced geographic information in order to solve complex management and planning problems. gvSIG is known for having a user-friendly interface,...
- GDALGDALGDAL is a library for reading and writing raster geospatial data formats, and is released under the permissive X/MIT style free software license by the Open Source Geospatial Foundation. As a library, it presents a single abstract data model to the calling application for all supported formats...
- MapServerMapServerMapServer is an open source development environment for building spatially-enabled internet applications. It can run as a CGI program or via MapScript which supports several programming languages . MapServer was developed by the University of Minnesota — so, it is often and more specifically...
- Web Map ServiceWeb Map ServiceA Web Map Service is a standard protocol for serving georeferenced map images over the Internet that are generated by a map server using data from a GIS database...
(WMS) - Web Feature ServiceWeb Feature ServiceThe Open Geospatial Consortium Web Feature Service Interface Standard provides an interface allowing requests for geographical features across the web using platform-independent calls...
(WFS)