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Figure 1
The five level of details defined by CityGML (Gröger et al., 2012)
Figure 2
The source data in 3D shapefile proprietary data format visualized in Esri ArcScene (buildings – red, bridges – blue and DTM – grey)
Figure 3
The setting of CityGML LOD name and feature role. According to this particular setting, the geometry of each building is represented in an output file as gml:MultiSurface at LOD2.
Figure 4
Generating gml:id attribute for buildings. The final value of gml:id attribute is based on the feature’s identifier contained in the source 3D shapefile (in this case ID_BUD attribute).
Figure 5
The transformation schema for buildings. After the input data are loaded into the memory, the LOD name and feature role are set. In the next step, the gml:id is generated. The conversion ends with writing CityGML into the output file.
Figure 6
Generated CityGML file for buildings. The file contains a spatial envelope (gml:Envelope), for which, extent is given by the coordinates expressed in requested coordinate reference system (in this case, with EPSG code 5514). The buildings are represented as multisurfaces at LOD2 (bldg:lod2MultiSurface).
Figure 7
The transformation schema for bridges. First, the input data are loaded into the memory, then the LOD name and feature role are set. In the third step, the gml:id is generated. The conversion of bridges ends with writing CityGML into the output file.
Figure 8
Generated CityGML file for bridges. The buildings are represented as multisurfaces at LOD2 (bldg:lod2MultiSurface).
Figure 9
Generating gml:id attribute for TINRelief features. The value ‘ReliefPrague’ of the attribute gml_parent_id corresponds to the gml:id of the parent feature (an instance of the class ReliefFeature).
Figure 10
Creation of the citygml_lod_name attribute (top) and its transformation into a trait (bottom)
Figure 11
The transformation schema for the digital terrain model. The numbers placed on oriented arrows show the number of features going from one node to another.
Figure 12
Generated CityGML file for relief represented as TIN (element dem:TINRelief)
Figure 13
The geometric validation for CityGML bridges using the val3dity tool. The summary states that all bridges are geometrically valid.
Figure 14
The 3D geospatial data covering the Prague city centre visualized in the 3DCityDB-Web-Map-Client
Figure 15
For 3D objects, their owners can be displayed. Charles Bridges is owned by Prague (see the info box in the right upper corner)
