184 4 Geometry standards
The vast majority of concepts in ISO 19107 have been implemented in GML 3.0
such as the fundamental geometries point, curve, surface, and solid, and the description of positions related to a Coordinate Reference System.
However, the conformance with other ISO 19100 standards does not require a 1to-l implementation. The implementation of classes in GML is driven by applications and requirements. In fact ISO 19107 states that is not expected that an implementation will implement all classes. On the other hand GML 3 contains some elements that are beyond the range of the other ISO 19100 standards. The class
GM _ OffsetCurve is an example of a class in ISO 19107 that has not been implemented by GML 3. The element ArcByCenterPoint is an example of an element in
GML 3 that does not exist in ISO 19107.
Relation to other ISO 19100 standards
The ISO 19118 sets the encoding for the geomatics standards. Although XML is
strongly preferred, the present version (lS050 2002) allows different encoding
schemas. It is planned to make an XML encoding a normative part of ISO 19118
(Encoding) (Annex C) as soon as GML has become an International Standard.
The ISO 19111 (Spatial referencing by coordinates) in general serves the needs of
GML 3. Some modifications have been identified and will be fed back to
ISO/TC211.
GML 3 contains a mechanism to include metadata, but there is no rule that only
ISO 19115 (Metadata) or later ISO 19139 (Metadata - implementation specification)
can be used. GML is open to integrate metadata from other source such as the Dublin
Core as weIl.
The ISO 19108 (Temporal schema), the ISO 19109 (Rules for application
schema) and the ISO 19117 (Portrayal) still need to be fully harmonized with
GML3.
4.6.4 A1ignment between 150 19136 and GML-development
As the ISO 19136 defines an implementation it will change more rapidly than the
abstract standards of the ISO 19100 family. It may happen that the version of GML
that finally becomes an International Standard may be outdated because the development of GML will go on in parallel to the process of ISO standardisation. Therefore provisions are made to sustain alignment between the ISO 19136 and GML.
If possible, new versions of GML should be backward compatible or provide for
an automatie mapping. The development of GML will have to take care that the conformance with the conceptual model ofthe ISO 19100 standards is maintained. From
the perspective of the geographie information community and the marketplace, if
there are good reasons for a change, the ISO 19100 conceptual model, the ISO 19118
(Encoding), or the OGC Abstract Specification, which GML is based on, should
change.
The vast majority of concepts in ISO 19107 have been implemented in GML 3.0
such as the fundamental geometries point, curve, surface, and solid, and the description of positions related to a Coordinate Reference System.
However, the conformance with other ISO 19100 standards does not require a 1to-l implementation. The implementation of classes in GML is driven by applications and requirements. In fact ISO 19107 states that is not expected that an implementation will implement all classes. On the other hand GML 3 contains some elements that are beyond the range of the other ISO 19100 standards. The class
GM _ OffsetCurve is an example of a class in ISO 19107 that has not been implemented by GML 3. The element ArcByCenterPoint is an example of an element in
GML 3 that does not exist in ISO 19107.
Relation to other ISO 19100 standards
The ISO 19118 sets the encoding for the geomatics standards. Although XML is
strongly preferred, the present version (lS050 2002) allows different encoding
schemas. It is planned to make an XML encoding a normative part of ISO 19118
(Encoding) (Annex C) as soon as GML has become an International Standard.
The ISO 19111 (Spatial referencing by coordinates) in general serves the needs of
GML 3. Some modifications have been identified and will be fed back to
ISO/TC211.
GML 3 contains a mechanism to include metadata, but there is no rule that only
ISO 19115 (Metadata) or later ISO 19139 (Metadata - implementation specification)
can be used. GML is open to integrate metadata from other source such as the Dublin
Core as weIl.
The ISO 19108 (Temporal schema), the ISO 19109 (Rules for application
schema) and the ISO 19117 (Portrayal) still need to be fully harmonized with
GML3.
4.6.4 A1ignment between 150 19136 and GML-development
As the ISO 19136 defines an implementation it will change more rapidly than the
abstract standards of the ISO 19100 family. It may happen that the version of GML
that finally becomes an International Standard may be outdated because the development of GML will go on in parallel to the process of ISO standardisation. Therefore provisions are made to sustain alignment between the ISO 19136 and GML.
If possible, new versions of GML should be backward compatible or provide for
an automatie mapping. The development of GML will have to take care that the conformance with the conceptual model ofthe ISO 19100 standards is maintained. From
the perspective of the geographie information community and the marketplace, if
there are good reasons for a change, the ISO 19100 conceptual model, the ISO 19118
(Encoding), or the OGC Abstract Specification, which GML is based on, should
change.