+horzontalCoordinateSystem 
i] —varticalCrerdinacaSyster 
  
  
  
  
3.1 UML diagram of building model in CityGML 
The City GML building model is minimized depending on the 
requirements of this paper work. The geometric representation 
and semantic structure of a Building model which defines as an 
_AbstractBuilding. The model is refined only from LODI to 
LOD2 due to the work purpose and requirement. For intuitive 
understanding of the UML model, classes will also be shown in 
different colours such as blue, green, yellow. The UML diagram 
of the building model is depicted in figure 3.2. 
  
  
  
  
  
Feuer 
  
leciass : Euiltingostaetcoclass Type © | 
prurdica : Bukchginstaltsion™ unaont 1s [2.1 < 
pustze. Suldrgnaalstiorisagst se 0.7] 
  
  
  
  
  
  
cass. SuikngttassT epe t2 f 
Mondion: Buldingr ancten t «ce 13 ^ 
  
  
  
  
  
  
  
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Figure 3.2: Overview UML diagram of City GML’s Building 
Model (Gróger, 2008) 
  
  
  
  
Figure 3.1: Overview UML diagram of Photogrammetric Tool's Building Model 
Also, not all aggregation levels are allowed in each LOD. The 
geometric representation is refined in LOD2 by additional 
MultiSurface and MultiCurve geometries, used for modelling 
architectural details like a roof overhang, columns, or antennas. 
For the LOD 1-2 group the geometries gml Solid, 
gml MultiSurface and gml MultiCurve are linked with the 
Abstract Building class (Gróger, 2008). 
3.2 Comparision of the data models 
When we compare the UML diagrams derived from the 
photogrammetric methods and ending with the CityGML 
Building model it is possible to define differences and 
similarities. The differences of the UML diagrams are defined 
such as complexity structure, XML based, Level of Detail 
(LODs) definition, geometry and semantic ...etc. (Tab.1) In 
ERDAS LPS, the building model can be defined with the UML 
classes in the workflow. So that the user who has aerial stereo 
images can be build a building model in the program. Also, the 
CityGML Building Model is a standard for the representation 
and exchange of 3D city and landscape models, issued by the 
Open Geospatial Consortium. 
  
  
  
  
  
  
  
  
  
Properties ERDAS LPS & CityGML 
ArcGIS Stereo 
Analyst 
Complexity Structure No Yes 
Semantic No Yes 
XML based No Yes 
Level of Details No Yes 
Geometry Multipatch Multi Surface 
Solid Type No Multi Solid 
Predefined Structure No Yes 
  
  
  
  
  
Table. 1: It shows the differences between ERDAS LPS & 
ArcGIS Stereo Analyst and CityGML Data models 
  
  
  
  
   
           
   
  
   
  
   
   
   
  
   
  
  
  
  
  
  
  
  
   
   
  
  
    
   
  
  
  
  
  
  
   
  
  
   
    
    
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