International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
updated documents at shorter intervals. Within a consortium the
big players set the standards. The smaller members do not have
the amount of influence they have in the ISO environment.
3. ISO/TC 211 “GEOGRAPHIC
INFORMATION / GEOMATICS”
The ISO/TC 211 was founded in 1994. Its predecessor is a
European standardization committee with a comparable scope.
This is the CEN/TC 287 “Geographic information”. CEN stands
for “Commité Europeen du Normes”. The titles of the 20 basic
standards of the ISO 19100 family had been defined by the
CEN/TC 287 already. In 1994 the U.S.A. and Canada with the
support of NATO (North Atlantic Treaty Organization)
proposed an extension of the standardisation of geographic
information on a worldwide platform. This was the beginning of
the ISO/TC 211.
Today (2004) the ISO/TC 211 consists of 55 national bodies, 23
of them participating members (P-members) and 22 of them
only observing members (O-members). Those national bodies
represent practically all nations of the world that are active in
the field of geographic information. In addition the ISO/TC 211
has 22 external and 12 internal liaison members. The liaison
members represent international technical expert organizations
that make considerable contributions to the content of the
standards. The internal liaison members are ISO or IEC
committees such as the ISO/TC 204 “Intelligent transport
systems". All other organizations are called external liaison
members. One of them is the ISPRS. The Committee of Earth
Observing Satellites (CEOS), the International Hydrographic
Organization (IHO), the Digital Geographic Information
Working Group (DGIWG) of NATO, and the OGC are other
examples of external liaison members, while the OGC probably
is the most important one of all. The P-members of the national
bodies have the right to vote. All other members only have the
right to comment.
The standards developed by the ISO/TC 211 are often called the
ISO 19100 family because their numbers range from ISO 19101
to ISO 19140 with the option of an extension until ISO 19199.
The standards may be categorized in six groups:
Groups Examples
1. Reference model
2. Infrastructure standards — Terminology,
Conformance and testing
Georeferencing, Spatial
schema, Metadata
Sensor and data models
for imagery and gridded
3. Basic standards
4. Imagery standards
data
5. Catalogue standards Feature cataloguing
methodology
6. Implementation standards GML, Web Map Server,
Location Based Services
(Kresse, Fadaie, 2004)
D
The standardization of the ISO/TC 211 follows a model driven
approach. This means that all standards are branches of an
overall model for geographic information. This model is written
in UML, the Unified Modelling Language.
The existence of an overall model basically says that every
individual standard is logically linked and harmonized among
the suite of standards. Components such as the point object that
is described by the class GM Point is defined only in one of the
standards while the other standards simply reuse this class in
their models.
The overall model does not mean that it covers every aspect of
geographic information. The practically completed suite of
standards covers the vector world, while other topics such as
imagery are still under development. Also, different expert
groups have been dealing with the standardization projects. As a
result, the standards differ in the level of detail and in
theoretical background. The ISO 19107 "Spatial schema" and
ISO 19123 "Coverage geometry and functions" are two very
comprehensive works for GIS geometry. However, the ISO
19107 is derived from the “Set Theory” while the ISO 19123 is
an industrial development by the OGC. Figure 1 presents the
UML class-diagram of the ISO 19107.
A common feature of all ISO standards is the principle “One
term — one meaning", which is valid throughout the whole
world of ISO standards. This has created and will maintain a
very stable terminology in the field of geographic information.
The range of definitions in most of the ISO 19100 standards has
been set as wide and generic as possible to enable their usage in
practically all fields. However, for many applications this range
is too large and needs to be narrowed for an efficient use. For
this purpose the ISO 19106 "Profiles" sets the rules. A profile
of conformance level 1 is a subset of the classes provided by a
standard. A profile of conformance level 2 is also a subset but
includes additional classes that have not been defined in one of
the ISO standards.
The ISO 19115 “Metadata” is probably the best known standard
of the ISO 19100 family. It provides a large basket of metadata
elements that are needed in applications of geographic
information. The ISO 19115 consolidates well known sources
such as the metadata listing of the FGDC (Federal Geographic
Data Committee of the U.S.) in one standard. The large
software providers for GIS have begun to incorporate the ISO
19115 in their system enabling the automated and backgrounded
generation of metadata elements while the GIS data are updated.
The metadata-model of the ISO 19115 distinguishes between
about 20 core metadata elements and the comprehensive listing
with about 400 elements. Figure 2 shows the package diagram
of the ISO 19115 that illustrates the areas of metadata support.
Outside the ISO another source of metadata definition is well
known. This is the Dublin Core. Its definition is a compact
listing of 15 elements originally designed for IT and library
purposes. The Dublin Core is not fully compliant with the ISO
metadata. However, government organizations such as the
European Union have adopted the Dublin Core requiring its
application cven in the field of gcographic information.
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