From Geostandards

Motivation

The INSPIRE Directive includes strong requirements with regard to both harmonisation and interoperability of spatial data. Enabling interoperable access to spatial data is one of the key goals of the Directive. Since INSPIRE covers 34 spatial data themes, a common framework is required to allow for cross-theme interoperability. This modelling framework is based on the following assumptions and principles:

• All Member States and organisations start from different positions in terms of data specifications, etc. Due to different political, economic, cultural and organisational drivers, it is not feasible (or desirable) to achieve total harmonisation across every nation as part of the INSPIRE process. Regional diversity will and should continue to exist.
• A mechanism that provides technical and conceptual interoperability to support needs at European and other large cross-border and cross-sector levels is required.
• The trend towards the integration of geographic information into the information and technology mainstream will accelerate.
• The main goal at least for the foreseeable future is to achieve interoperability through harmonised data product specifications on the European level rather than harmonisation of the underlying conceptual models (and restructuring the associated data sets) in the Member States. Any requirements to change the existing data will be kept to a minimum.
• Two aspects of the process to enable interoperability need to be distinguished:
  • a common process and methodology of developing data specifications in order to have a harmonised, consolidated conceptual schema for all the themes involved in INSPIRE;
  • for every individual data specification a conceptual schema needs to be designed that is capable of representing data from the various data sources and providers that need to provide the content for the view and download services.
• In this context data interoperability requirements have to be considered on different levels:
  • the specification level (use of common data specifications independent of the specification of the source data in the Member States)
  • the metadata level (provision of metadata according to a common metadata profile as specified in the implementing rule on metadata)
  • the data level (e.g. edge matching in border areas)

The framework documents

The INSPIRE Modelling Framework consists of the following four documents:

• Generic Conceptual Model, version 3.2
• Guidelines for the encoding of spatial data, version 3.1
• Methodology for the development of data specifications: version 3.0
• Definition of Annex Themes and Scope, version 3.0

The first two contain requirements and recommendations for the INSPIRE data specifications, the other two documents contain requirements, recommendations and input to the process of creating the INSPIRE data specifications.

The "keep it simple" approach

The main goal of the INSPIRE Modelling Framework documents is to support the development of INSPIRE data specifications for the themes so that the individual specifications are developed in a homogeneous way. The general approach is to try to follow a “keep it simple” approach to developing rules for the wide thematic range of INSPIRE data specifications. Simplicity has been in the focus in particular for two aspects:

• The processing and use of INSPIRE data (it is assumed that INSPIRE data will typically be accessed through download services which are assumed to provide direct access to spatial objects) should be as simple as possible for users and their software applications.

An example of a resulting rule is the definition of a well-documented set of coordinate reference systems which may be used in INSPIRE data so that an INSPIRE-aware software application is guaranteed to be able to spatially relate two different spatial objects from different data providers.

Another example is the recommendation to use the Simple Feature specification as specified by OGC for geometries wherever feasible, because many software components dealing with spatial data sets are able to deal with geometry data following this specification.

As a basic rule, INSPIRE has to support the user requirements and be feasible. Therefore, INSPIRE data specifications are based on the various existing/emerging spatial data infrastructures and relevant existing standards processes within international communities. I.e., limitations of software components are not in the main focus. However, it also needs to be ensured that what is specified in the INSPIRE Implementing Rules can be implemented in the ICT infrastructure of the data providers and the users. All this, of course, without locking INSPIRE into specific solutions/platforms or inhibiting the future development of the SDI in the context of the general ICT development. Naturally, this is a grey area and to an extent it will only be clear in the future if the right balance was found.

As a result, the general approach is to provide strict rules only where absolutely necessary. Otherwise, general restrictions are avoided, but recommendations are provided where they were considered as a useful guideline.

The Simple Feature specification is a good example for a recommendation as it is standardised (and has gone through a consensus process), is supported by many implementations and used in many operational systems (very likely meeting the conceptual requirements of the applications). There are, however, many applications that go way beyond what Simple Features provides/supports and in this case it is expected that the INSPIRE data specifications will do so, too. In a similar sense, while many spatial applications are based on this specification, a larger number of applications today go far beyond what Simple Feature supports.

• For data providers the publication of their existing spatial data sets as INSPIRE conformant spatial data sets should be as simple as possible.

An example is the structure of identifiers of spatial objects that has been specified with as few rules/parts as possible and supporting the reuse of already established unique object identifiers in existing spatial data sets while at the same time addressing all the INSPIRE requirements.

As noted above, in general some of these aspects can be conflicting goals and the conceptual modelling framework tries to find a reasonable compromise between them in case of conflict.

An integral part of any SDI development is an agreement on the technical standards that form the basis for interoperability between the parties in the infrastructure.

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Infrastructure for Spatial Information in the European Community (INSPIRE)

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