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Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved.
formats. This is in contrast to a Web Coverage Service WCS, which returns actual raster data.
WMS defines three operations: o
GetCapabilities, which returns service-level metadata. o
GetMap, which returns a map whose geographic and dimensional parameters are well-defined.
o GetFeatureInfo, which returns information about particular features shown on
a map optional.
9.7.3 OGC Web Coverage Service
The Web Coverage Service is an Open Geospatial Consortium standard web service for exchanging geospatial raster data.
WCS provides available data together with their detailed descriptions; allows complex queries against these data; and returns data with its original semantics instead of
pictures which can be interpreted, extrapolated, etc. -- and not just portrayed. This is in contrast to a Web Map Service WMS which produces a digital image file.
WCS provides three operations: o
GetCapabilities, which returns XML document describing the data collections available via WCS.
o DescribeCoverage, which returns details about a specified data collection.
o GetCoverage, which returns the data in a well known format.
9.7.4 OGC Web Feature Service
The Web Feature Service is an Open Geospatial Consortium standard web service for defining interfaces for data access and manipulation operations on geographic features
using HTTP as the distributed computing platform. Via these interfaces, a web user or service can combine, use and manage geodata
– the feature information behind a map image
– from different sources by invoking the following WFS operations on geographic features and elements :
o Create a new feature instance,
o Delete a feature instance,
o Update a feature instance,
o Lock a feature instance,
o Get or query features on spatial and non-spatial constraints.
Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved.
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9.7.5 OGC Sensor Observation Service
The Sensor Observation Service in an Open Geospatial Consortium standards web service for exchanging sensor observation data.
9.8 Processing Services
Earth Observation data will not always be well-suited to a specific purpose and will need processing specific to the users needs. This situation is typical in environments were data
is acquired and archived for one application but this is accessed for by a user with a different application than the original application.
Extensive tests have been performed as well within the ESA Grid infrastructure leading to a preliminary definition of a Grid-based Processing Service. This with the objective of
reducing the burden caused by the transfer of large EO coverages by transferring instead the processing algorithms on the Grid that hosts within its storage element the coverages
to be processed.
The OGC Web Processing Service WPS defines a standardized interface that facilitates the publishing of geospatial processes, and the discovery of and binding to thse processes
by clients. ―Processes‖ include any algorithm, calculation or model that operates on spa
tially referenced data. ―Publishing‖ means making available machine-readable binding information as well as human-readable metadata that allows service discovery
and use.
9.9 Orthorectification and re-projection services
Ortho-rectification and re-projection of remote sensing images is an important issue for various applications. Indeed, the image orthorectification and re-projection process
combines relief effects corrections and geo-referencing with high location accuracy.
The OGC Web Coordinate Transformation Service WCTS is another processing service that was experimented with, in combination with Spot Image Web Coverage Service as
