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5.2 Different geometry types 
In Finland the forest is not available as an area feature. The 
large scale topographic map depicts forest by a point symbol, so 
does the topographic database (see Figure 3). Area colours (in 
the map) or area features (in the database) are used for other 
land cover features such as agricultural land, mire, meadow and 
water body. The built-up area and forest share the background 
(white colour in the map) The human map reader can 
distinguish these two land cover classes from each other by 
interpreting the symbols for individual houses and trees, but this 
method is not easy to implement in a geographical information 
system (GIS). 
  
  
  
  
  
  
  
  
  
  
Figure 3: Finnish Forest as point feature type 
5.3 Differences in conceptual modelling 
Some feature types and attributes of the Global Schema have no 
or only ambiguous relationship with the Local Schema because 
of the significant differences in conceptual model, related e.g. 
to watercourses. The GiMoDig Global Schema proposes a 
classification into feature types 'Water except Inland' (i.e. Sea, 
Ocean), 'Watercourse' (which aggregates 'River', 'Canal' and 
Ditch) and 'Lake/Pond'. Sweden does not distinguish 'Ocean' 
from 'Lake' and from area-type 'River', instead they put all 
instances into one feature type 'Vatten' and only separate area- 
type features from line-type features. Finland has a similar 
approach but distinguishes at least the "Water with Current' 
(Watercourse) from 'Water without Current' (Ocean, Lake). For 
visualisation purpose this generalised approach does not matter 
since all water area is displayed in same blue colour, but for 
GIS applications the approach of Sweden and Finland may lead 
to difficulties. : 
Denmark does not make any distinction between ‘Airports’, 
Railway stations’ or 'Power Plants. They are all together 
recorded as 2700 "Technical Area'. 
Another problem in Denmark is the 3119 'Recreational Area'. 
This feature type comprises all kind of recreational areas, e.g. 
"Amusement Park', 'Campground' and also 'Park'. There is no 
attribute that further specifies the instances according to the 
type of the recreational area. 
The criteria for classification of roads into primary, secondary 
or local road differs between countries. Germany applies the 
official administrative categories. The other countries classify 
by the width of the road. There is no uniform European 
classification scheme except for the few trunk routes with 'E'- 
numbers. 
5.4 Differences in data modelling 
Concerning data modelling there also exist differences between 
the four participating countries. 
The German dataset differs from the data model of the 
Scandinavian partners especially for roads with separated lanes. 
The NMAs of Sweden, Finland and Denmark portray the lanes 
in each direction with individual centre lines. In contrast, the 
German dataset models the motorways by a complex feature 
that is composed of road body (one centre axis) and road lanes 
(two centre lines). For the Global Schema we decided to include 
only the individual lanes and skip the centre axis of the German 
motorway, with the lanes inheriting the attributes from the 
complex feature and the road body. 
Concerning railway features each track is modelled separately 
in Finland, Sweden and Denmark. It appears that Finland shows 
the complete layout whereas Sweden and Denmark apply some 
generalisation. Double track railways appear as two parallel 
lines in Finland and Denmark. In Sweden and Germany the 
railway is recorded as a single centre line if tracks are parallel, 
the number of tracks is stored as an attribute. In case of tracks 
not being parallel the German data model applies a complex 
feature like the motorway. In case of complex railway yards or 
stations the German data model applies an area-type feature 
railway station’ where onky the major track is continued 
through the area and connected with the railway lines leading 
to/from the station. In the Global Schema we keep both 
approaches as it is neither feasible to generalise the 
Scandinavian track layout nor to add the missing tracks to the 
German data. 
5.5 Level of Detail 
From the sample data in the cross-border test areas it becomes 
obvious that the level of detail differs from country to country. 
Germany and Denmark have great differences in their 
hydrographic network. The network of drainage canals and 
ditches in Denmark is much denser than in Germany. The 
difference is less significant in hill areas where the selection 
criteria for natural watercourses appear quite homogenous at 
both sides of the border. 
The hydrographic network at the border between Sweden and 
Finland can be compared with the German-Danish example. 
The network of artificial watercourses appears much denser in 
Finland than in Sweden. Another problem illustrated in the 
example is the lack of connectivity in the Finnish and Swedish 
network. We can recognize many gaps and isolated objects (see 
Figure 4).