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Standards framework for geographic information



The Solid Earth and Environment community is primarily concerned with data whose spatial context is significant, so operates as a specialised group within the geographic information community. Standards for generic geographic information processing are under development in several forums. The standards and specifications from these organisations are large documents containing a considerable amount of detail. They are also highly interdependent. This makes it a significant task to assimilate and evaluate the necessary information.

Brief summaries of the scope of key standards are given below. Within the roadmap we refer to many of the standards, in the context of a discussion of the specific issues confronted when designing an information model and encoding for communities within the Solid Earth and Environment sector.

ISO/Technical Committee 211

TC 211 is concerned with standardising general geographic information and services. It is responsible for the ISO 191** series of standards. The ones earlier in the series have been issued. These are concerned with establishing the conceptual framework, and providing detailed specification of certain mature areas (such as spatial components), particularly in terms of data models. The ones later in the series are mostly still incomplete. These include standards for services, and standards that describe “profiles” of the abstract models in order to make them more directly applicable, or define implementations based on the abstract models.

Note, that these specifications present the models at a relatively abstract level, mostly using UML notation, and are not directly implementable.

Of particular interest in the context of this discussion are the following documents.

(Also see https://www.seegrid.csiro.au/twiki/bin/view/Xmml/IsoTc211Standards)

Information model

The meta-models for geographic information are described in three basic standards:
  • ISO 19109 "Geographic Information - Rules for Application Schema" which gives a formal description of the General Feature Model - International Standard due 2004
  • ISO 19110 "Geographic Information – Methodology for feature cataloguing" which describes the basic approach to listing feature types for a community - International Standard due 2004
  • ISO 19123 "Geographic Information - Schema for coverage geometry and functions" which gives a formal description of the important alternative to the feature model, the spatial function or coverage

The following documents provide detail in some critical areas:
  • ISO 19107 “Geographic Information - Spatial Schema” which describes a consistent set of geometric objects and operations useful in geography
  • ISO 19108 “Geographic Information - Temporal Schema” which describes a set of temporal objects, systems and operations
  • ISO 19111 “Geographic Information – Spatial referencing by coordinates” which provides a model for coordinate reference systems and transformations
  • ISO 19112 “Geographic Information – Spatial referencing by geographic identifier” which provides a model for geocoding, in particular covering the “gazetteer” use-case

Governance and deployment

  • ISO 19135 "Geographic Information – Procedures for registration of items of geographic information" which outlines governance models for maintenance of a catalogue
  • ISO 19126 “Geographic Information - Profiles for feature data dictionary registers and feature catalogue registers” which gives more details of how to generate and document a profile of a feature catalogue under a reasonable governance model, with several examples from key communities that may be considered archetypal

Encoding

  • ISO 19103 “Geographic Information - Conceptual Schema Language” which describes a profile of UML that is used consistently in the rest of the standards - Technical Specification due 2004
  • ISO 19118 "Geographic Information - Encoding" which describes a general interchange model and methods for mapping UML models to XML
  • ISO 19136 "Geographic Information - Geography Markup Language" which provides a detailed XML schema for geography, including components covering geometry and topology, the feature model, temporal, coverages.
  • ISO 19139 "Geographic Information - Metadata - Implementation Specification which provides a comprehensive dataset metadata implementation specification, providing single UML interpretation and XML schema for carrying out ISO 19115:2003 metadata standard.

ISO/Technical Committee 204

TC 204 is concerned with intelligent transport systems, and has developed standards covering location based services.

Open GIS Consortium

OGC is a membership consortium that develops openly available specifications for geographic information products and services. OGC currently focusses on defining interfaces for web-hosted geoprocessing. There is a close relationship between OGC and ISO/TC 211: OGC has adopted many ISO 191** standards as its “Abstract Specification” and is submitting its “Implementation Specifications” for adoption by ISO. Note that OGC implementation specifications are based on the abstract specifications, but are subject to testing through the OGC “Interoperability Program” prior to adoption.

Of particular interest in the context of this discussion are
  • Geography Markup Language (GML) - version 3.1 is currently undergoing standardisation as ISO 19136, see above
  • Web Map Service (WMS) - defines standard request/response syntax using http GET and POST, for requesting maps encoded in image formats (gif, jpeg, png etc) - version 1.3 is due to be issued as ISO 19128
  • Web Feature Service (WFS) - defines standard request/response syntax using http GET and POST, for requesting collections of feature instances of a specified type, encoded in GML (required) or other formats (optional)
  • Filter Encoding - defines syntax for selecting a set of feature instances on the basis of particular values of their properties (including geometry). Used in conjunction with WFS
  • Web Coverage Service (WCS) - defines standard request/response syntax using http GET and POST, for requesting coverages encoded in well known imagery formats or GML. Currently targetted at subsets and slices through gridded coverages, but expected to be generalised
  • Catalogue Services for the Web (CS/W) - RobAtkinson summarise here?


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Topic revision: r3 - 15 Oct 2010, UnknownUser
 

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