may consider that a rather stable consensus was reached already
in 2001. The latest work within INSPIRE has reviewed the
original concepts and requirements, and arrived to choose a new
term “Basic Data”, that comprise the following components:
1) Referencing systems
e Coordinate reference systems
e Geographical grid systems
e Geographical Names
e Addresses
2) Common reference data
e Administrative units
e Transport
e Hydrography
e Elevation
e Cadastral parcels
e Ortho-imagery
3) Other priority environment common themes
e Protected sites
e Land cover
This basically lists the main body of most NMCAs mission and
remits; it is their *core-businesses', except possibly for the two
last items. Therefore EuroGeographics recognise its
responsibility into leading this part of the work of building the
ESDI.
1.6 State of the art
A first step in EuroSpec was to assess today's current situation,
as well as plans and capacities to change, in relation to the
Common Reference Data. A survey has been realised in the
beginning of 2003, which main results confirm the timeliness of
the EuroSpec project. The survey has been conducted by Antti
Jakobsson and EuroGeographics Expert Group on Quality, and
the results are available on EuroGeographics web site (see
references).
The survey was made trough a questionnaire sent to all
European NMCAs, and covered three themes: organisations,
databases, and reference data components. Components were
selected after the INSPIRE definition, and the FACC data
dictionary has been used for feature types. Twenty-seven
countries answered the questionnaire, which gives a quite good
overview of the situation in Europe. Here is a summary of the
answers.
In about one-third of the countries only one organisation — the
primary EuroGeographics member — is producing all reference
data components. This responsibility can also be shared
between 2 organisations (in 8 countries) or more, with a
maximum of 18 in Germany, due to its federal status.
Topographic databases exist in 19 countries, but all countries
had topographic data in some format. The database structures
are illustrating the fact that we are in an era of change, as the
following numbers measure the on-going transition from
‘digital mapping’ to ‘geographic information’: object-based in 8
countries; plan to convert to object-based in 6 countries; point-
line in 5 countries; digitised themes in 7 countries. This same
pattern shows also with Cadastral databases which exist in 21
countries (no data in 6 countries): object-based in 10 countries;
plan to convert to object-based in 5 countries; point-line in 6
countries.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
Most topographic databases are at scale 1:10.000, three at a
larger scale (maximum 1:1.250), and three at a smaller scale
(minimum 1:100.000). Digital Elevation Models exist in 20
countries, with a typical resolution of 25m in 10 countries
(maximum $m, minimum 100m); orthophotos in 21 countries,
with typical resolutions between 20cm and 1m for most. Most
countries apply national standards, and the move towards
international standards is only starting (eg. in Germany, the
Netherlands).
A more detailed exploration of the available individual
components and main feature types brings the following
preliminary conclusions:
e Reference data themes are generally available in Europe
(but less than 8096 availability in some themes or features:
addresses, parcels, interchanges and built-up areas)
e Topographic data is not yet object-based in majority of
countries but the change is in progress (14 out of 19 in few
years)
e Data is in two accuracy levels according to the source
(digitised from maps or direct surveys using aerial
imagery)
1.7 Interoperability
It is assumed (ETeMII, INSPIRE, etc.) that interoperability of
geographic information is a requirement of the ESDI, and that
the development of common specifications, in particular for the
Common Reference Data is necessary for that interoperability.
But exactly ‘what interoperability?” and ‘what specification?’ is
still under discussion. Although there are many aspects to
interoperability, they may be brought — for GI — within two
main levels, according to the aim.
Hybrid Mapping:
In “Hybrid Mapping” current framework data is brought
together (juxtaposed) and eventually superimposed with
business data. Initially this is on an 'as-is' basis, but using
coordinate reference systems services to establish common
coordinate reference. If discrepancies arise, they are due to
‘error’ — i.e. in edge-matching or because of different accuracy
standards or capture specifications (across framework data
jurisdictions or 'vertically' between layers). There will of course
also be coding discrepancies.
Hybrid Mapping is achievable using the current OGC Web Map
Service (WMS) and Web Feature Service (WFS) specifications.
The Style Layer Description (SLD) or Scalable Vector Graphics
(SVG) specifications will support suitable cartographic styles
(but not a consistent cross-border style, unless by good fortune).
Hybrid Mapping, despite its deficiencies, would offer a
considerable step towards interoperability. In theory, all the
(horizontal) coordinate reference issues should be dealt with
correctly. There would be a significant degree of selectivity (of
'layers' or 'themes' within the reference data) and freedom to
superimpose business data. A simple level of query would be
supported (simple feature basis), although the results would not
be consistent across boundaries.
Consistent Mapping:
Ultimate interoperability should keep all the intelligence of the
information after the integration process, and must be seamless:
only thus can be fully exploited the data for any spatial
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