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Geospatial Standards

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The ISO 19100 framework

Information communities

ISO 19101 describes a reference model for interoperability in GI. An important premise is that, since technical communication occurs primarily between members of a community operating within a "universe of discourse", the language that they use is scoped to their domain, and thus should be governed by the community. Thus, the focus is firmly on the community working within a domain to develop agreement, concerning the model used in their subject domain.

A significant issue concerns delimiting the community within which agreement may be reached. This may be as small as a workgroup, but becomes interesting when the membership of the group crosses institutional boundaries. It may not be possible to achieve complete formal agreement amongst all interested parties, so strategies for reconciling models from different communities within the same conceptual domain will often be required. See InteroperabilityConsiderations for some additional discussion.

However, by using a common framework, including sharing the definitions of elements that are common between domains working with GI, some level of interoperability across domain boundaries is obtained.

ISO 19109 describes the rules for developing an Application Schema, which is a formalization of a domain model, scoped for one or more implementation environments. Formalization is based on modeling the domain in terms of the feature types that occur in the domain, so the standard defines a general feature model (GFM). A "feature" is a typed item of interest from the domain. The feature type is defined by a characteristic set of properties, which includes attributes, operations, and association-roles. Note that, while features often correspond with spatial-temporal objects (e.g. mine, road, parcel, person, earthquake, project) any identifiable item of interest in a domain may be treated as a feature (e.g. set of portrayal-rules, license).

Governance elements

ISO 19110 provides a template for the description of a Feature Type Catalogue for a domain.

ISO 19135 provides a rigorous model for registration, in particular identifying various roles in the management of registers and the lifecycle of registered items.

Model formalization

ISO TS 19103 describes the Conceptual Schema Language that should be used for formalization of information models, which is a profile of UML. The focus is on class diagrams, and amongst other things the profile specifies
  • standard class stereotypes (e.g. «Codelist», «Union»)
  • a set of common basic datatypes (e.g. Measure, ScopedName), and template classes that may be used for aggregates
  • some patterns to constrain UML's flexibility in class modelling (e.g. every navigable association end must carry a rolename).

Common elements for geospatial information

A series of standards provide definitions of some common components, of cross-domain interest within GI, including:
  • ISO 19107 and ISO 19108, for spatial- (geometry+topology) and temporal-objects, repectively;
  • ISO 19111 for spatial referencing (i.e. model for defining coordinate systems);
  • ISO 19123 a model to be used to describe properties that vary within a spatio-temporal domain.

XML Implementation

ISO 19136 (Geography Markup Language, v3.2.1) provides a W3C XML Schema-based implementation of many of these, including standard XML encodings for the common components, and base-types for the development of application schemas. Integration with the ISO 19100 framework is achieved through rules for conversion of a domain model described using the UML profile and components, to an XML Schema that imports the GML components and base-types. This includes some additional package stereotypes («ApplicationSchema», «Leaf») class stereotypes (e.g. «FeatureType»), and tagged values on various elements of the model that fine-tune the XML implementation of the model.

GML conformance requires that the the XML Schema-type of elements in an application schema be derived from specific parent types provided by GML. In particular, all feature-types are derived from gml:AbstractFeatureType.

Open Geospatial Consortium

OGC focuses primarily on architectures for distribution of geospatial services, and implementation of ISO standards, through service interfaces and data models and encodings.

The INSPIRE methodology

The INSPIRE Methodology for the development of data specifications contains relevant guidelines concerning the feature-modelling methodology. The process described in clause 5 of the document is derived from the framework provided by ISO 19103, ISO 19109, ISO 19110, ISO 19126, ISO 19131 and ISO 19135, and is essentially independent of INSPIRE-specific details. It is recommended that this is consulted in preparation for designing a domain model

Clause 5.1 outlines an iterative/spiral development process. This starts with an analysis of use-cases to determine requirements, followed by an analysis of existing models and harmonization opportunities, leading up to development of the conceptual schema, documentation, pilot implementation and testing.

Clause 5.2 concerns formalization of the model, following the ISO 19100 framework. Two kinds of models are distinguished:
  1. the conceptual model, formalized as model of classes, their attributes and associations
  2. platform specific implementation models, which may need to conform to a more restricted profile of UML, and also require some specific choices relating to names, sequences, etc. A couple of checklists are provided, which can focus the activity.

 
Topic revision: r5 - 15 Oct 2010, UnknownUser
 

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