38
2 Geomatics standards
called an instance of the feature "hiking trails". Some features have special relationships that become important once a map is drawn, or networking algorithms are applied to the dataset. An example for this case is the bridge crossing the streams. The
bridge will always go over the stream at a different elevation than the water surface.
This relationship is an association between features.
It is obvious that the possible features of a GIS have to be agreed upon before the
population of the database starts. The result of this design process is basically a listing of all allowed features together with their attributes, operations, and associations.
The listing is called a feature catalogue. The complete result is called a data model.
I TG 8uildmgs I
I TG_Theatre I
I
I
I TG Traffie I
I TO Road I
I TG HikingTrail I
I TG Parking I
I GF JeatureType I
I TGJeatureType I
I
I
1 TG_Brldge
Bridge above Stream
!;l
I TG Landuse I
TG Field J
I
I
L TG_Wood J
I TG_Beach I
I TG AboveUnder I
L
I
l
J
NC."","",~
I TG Water I
L TG_Lake J
I TG Siream I
I GF AssociationType I
Stream under Bridge
Fig. 2.3. Data model ofthe tourism-GIS shown as a UML class-diagram
All classes of the tourism-GIS start with the two characters "TG" to indicate their relation to
the tourism-GIS.
(Hint: UML, the Unified Modelling Language, is addressed in seetion 3.1.1)
The ISO does not standardise feature catalogues and data models. The only guidance provided is the ISO 19110 (Methodology for feature cataloguing). This standard provides the general rules and a catalogue-template to support a complete and
consistent listing.
The following list is a simplified feature catalogue for the tourism-GIS.
2 Geomatics standards
called an instance of the feature "hiking trails". Some features have special relationships that become important once a map is drawn, or networking algorithms are applied to the dataset. An example for this case is the bridge crossing the streams. The
bridge will always go over the stream at a different elevation than the water surface.
This relationship is an association between features.
It is obvious that the possible features of a GIS have to be agreed upon before the
population of the database starts. The result of this design process is basically a listing of all allowed features together with their attributes, operations, and associations.
The listing is called a feature catalogue. The complete result is called a data model.
I TG 8uildmgs I
I TG_Theatre I
I
I
I TG Traffie I
I TO Road I
I TG HikingTrail I
I TG Parking I
I GF JeatureType I
I TGJeatureType I
I
I
1 TG_Brldge
Bridge above Stream
!;l
I TG Landuse I
TG Field J
I
I
L TG_Wood J
I TG_Beach I
I TG AboveUnder I
L
I
l
J
NC."","",~
I TG Water I
L TG_Lake J
I TG Siream I
I GF AssociationType I
Stream under Bridge
Fig. 2.3. Data model ofthe tourism-GIS shown as a UML class-diagram
All classes of the tourism-GIS start with the two characters "TG" to indicate their relation to
the tourism-GIS.
(Hint: UML, the Unified Modelling Language, is addressed in seetion 3.1.1)
The ISO does not standardise feature catalogues and data models. The only guidance provided is the ISO 19110 (Methodology for feature cataloguing). This standard provides the general rules and a catalogue-template to support a complete and
consistent listing.
The following list is a simplified feature catalogue for the tourism-GIS.