3.2.14. WaterBody schema¶
The modelling of the WATERBODY database schema corresponds largely to the respective UML model. For LoD0 and LoD1 additional attributes are added, e.g. for modelling river geometry (LODx_MULTI_CURVE).
The geometries of LOD0 and LOD1 areal water bodies are stored within the table SURFACE_GEOMETRY. The foreign keys LODx_MULTI_SURFACE_ID (with 0 ≤ x ≤ 1) refer to the corresponding rows. Geometry for water filled volumes is handled in a similar way using foreign keys LODx_SOLID_ID (with 1 ≤ x ≤ 4).
For mapping the boundedBy aggregation which identifies the water body’s exterior shell managed by the WATERBOUNDARY_SURFACE table, the additional table WATERBOD_TO_WATERBND_SRF is needed to realise the m:n relationship.
The exterior shell of a WaterBody can be differentiated semantically using features of the type _WaterBoundarySurface. These features are stored in the WATERBOUNDARY_SURFACE table and can be distinguished by the OBJECTCLASS_ID attribute:
- 11 (WaterSurface)
- 12 (WaterGroundSurface)
- 13 (WaterClosureSurface)
If a CityGML ADE is used that extends any of the named classes above, further values for OBJECTCLASS_ID may be added by the ADE manager. Their concrete numbers depend on the ADE registration (cf. Section 5.3.4).
Since every _WaterBoundarySurface object must have at least one associated surface geometry, the foreign keys LODx_SURFACE_ID (with 2 ≤x ≤ 4, no MultiSurface here) are used to realise these relations.