Reference Information

General and functional definitions
While the scope of INSPIRE is very wide, EuroSpec concentrates on the spatial data themes that fall within the general remits of its member organisations, the NMCAs, and thus mostly focuses on annexes I and II of INSPIRE. EuroSpec actually focuses on those themes that were earlier designated as "reference data" in the ETeMII white paper, to be later endorsed by the INSPIRE RDM (Reference Data and Metadata) position paper of October 2002.

The EteMII "White paper" reminded us that the origin of the concept ‘reference data’ is based on two main ideas:
  • “It is a series of datasets that everyone involved with geographic information uses to reference his/her own data as part of their work.
  • It provides a common link between applications and thereby provides a mechanism for the sharing of knowledge and information amongst people.”

In addition, the INSPIRE RDM group wanted to stress that it is used as a common base to which thematic data may be referenced. The main functional requirements that geographical reference data must fulfil are:

  • “Provide an unambiguous location for a user's information
  • Enable the merging of data from various sources
  • Provide a context to allow others to better understand the information that is being presented.”

EuroSpec scope and the INSPIRE directive components
Adopting the above principles, EuroSpec will concentrate on the following components of the INSPIRE Directive:

>> From annex I - 6 components out of 7 (‘Protected sites’ to being exhaustively addressed):

1. Coordinate reference systems
2. Geographical grid systems
3. Geographical names
4. Administrative units
5. Transport networks
6. Hydrography

>> From annex II - 4 components out of 5 (‘Land cover’ to being exhaustively addressed):

1. Elevation
2. Identifiers of properties
3. Cadastral parcels
4. Orthoimagery

>> From annex III - 2 components out of 19

1. Statistical units
2. Buildings

It is assumed that these components constitute together the Reference Information that satisfies the criteria and conditions identified by ETeMII and INSPIRE, and consequently that achieving interoperability of those is the necessary condition for interoperability of all other geo-located information and services.

They are also the scope of EuroGeographics, as being the shared remit of its member NMCAs. A preliminary “State of the art of Reference Information in Europe” is available in a report based on an extensive survey of the European NMCAs information assets.

Base Reference Information
NMCAs deal with reference information at various resolution levels, suitable to a variety of applications and needs. “Base Reference Information” is defined as being the central and main source of an NMCAs national data repository, maintained at the most detailed level, from which others are generally derived, and is said today to be typically equivalent to a map representation at scale 1:10.000. In consequence this is the resolution level that is central to the EuroSpec programme, and the objective of its long term plans, while short term implementation will pragmatically consider lower resolutions and priority components.

Base Reference information content will be more precisely defined within further phases of EuroSpec, and may include discrete topographic feature elements (e.g. sections of watercourses, lakes/ponds, road segments, railway tracks, buildings, coastlines/shorelines, buildings) sometimes with their associated distinctive or descriptive names, cadastral boundary features, DTMs and orthoimagery.

Other types of Reference Information
“Associated Reference Information”
covers all other detailed reference information, that will need to be interoperable with the base reference information. This generally reflects “real world features” (i.e. schools, university campus, hospitals and railway station extents etc), and objects that are more widely recognised by users. These will generally be collections of discrete topographic objects. This sub group of reference information includes transport networks and water networks, addresses and the legal definitions of property ownership, boundaries, geology and so on.

“Application Information”
is largely that collected by users. It may be textual, images or geographic in nature, but largely it will be collected to support a business process. Where such information requires georeferencing it will be referenced with one or more of the Reference Information layers. For example river quality samples will be referenced against rivers, traffic flows against roads, births/deaths against addresses. Application information may be connected to the European and national Reference Information through suitable methods.

The interoperability requirements for Associated Reference Information and of Application Information may be the main driving force for achieving Base Reference Information, the second being the foundation of the first, and of the operational implementation of the ESDI.

Derived Reference Information” / “Lower Resolution Information”
is either information only collected at low resolution (e.g. 1:250,000) or is generalised from the Base or Associated Reference Information. Associated Reference Information generally lends itself to generalisation whereas the rule base and attribution of (topographic) Base Reference Information requires significant investment. Derived reference information includes generalized topographic features suitable for presentation in small scales e.g. 1:250 000 and 1:1 000 000 or any information that is processed and delivered using different models to meet different user needs (e.g. mobile PDA, desktop, integrated information system).

“EuroSpec Reference Information”
is derived from the national Reference Information transformed to a common specification. It might be available through a data service or as a database. It presents national Reference Information in a common coordinate reference system (ETRS89), data model and semantics system. It is available seamlessly at the national borders or as discrete (national or sub-national) contributions.

Although seamless it may be necessary to publish the information using several different quality levels (i.e. nationally). This will be specified in the metadata. While the detailed information (Base Reference Information) may be used for geo-referencing at national level, it is likely that this will not be complete for several years on a pan-European coverage. Meanwhile some form of derivation (or lower resolution) of the Base Reference Information will be made available to support the publication and analysis of application information at a pan-European level – e.g. river quality across Europe. EuroSpec will integrate these distributed and different national datasets/databases into a coherent and seamless European set of services to a common specification yet maintained at the national level.