3.2.14. WaterBody schema

WATERBODY, WATERBOD_TO_WATERBND_SRF

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.

WATERBOUNDARY_SURFACE

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.