220.127.116.11. Bridge Model¶
The bridge model, described in paragraph Section 18.104.22.168 at the conceptual level, is realised by the tables shown in Fig. 2.46. The relational schema is identical to the building schema for the most parts except for the naming. Please, refer to the explanation of the building schema on the previous pages for a complete understanding. The main differences to the building schema are the following:
- Bridges cannot be modelled in LoD 0. Therefore, no corresponding columns appear in the BRIDGE table.
- CityGML features belonging to bridges, such as boundary surfaces, installations, openings, rooms and furniture, are mapped to separate specific tables and are not stored in already existent ones (e.g. THEMATIC_SURFACE, OPENING, ROOM). Thus, values in OBJECTCLASS_ID columns are different as well. The reason for this is to provide a schema that is as close to the UML model as possible. There are slight differences between the building and the bridge model that would lead to ambiguous references e.g. a boundary surface of the building namespace cannot reference to a bridge construction element.
- OBJECTCLASS_ID of table BRIDGE_THEMATIC_SURFACE allows the values:
- 68 (BridgeCeilingSurface),
- 69 (InteriorBridgeWallSurface)
- 70 (BridgeFloorSurface),
- 71 (BridgeRoofSurface),
- 72 (BridgeWallSurface),
- 73 (BridgeGroundSurface),
- 74 (BridgeClosureSurface),
- 75 (OuterBridgeCeilingSurface),
- 76 (OuterBridgeFloorSurface).
If a CityGML ADE is used that extends any of the classes named above, further values for OBJECTCLASS_ID may be added by the ADE manager. Their concrete numbers depend on the ADE registration (cf. Section 22.214.171.124.1).
- In the BRIDGE_INSTALLATION table external bridge installations can be identified by the OBEJCTCLASS_ID 65 and internal ones by 66.
- The CityGML class BridgeConstructionElement is represented by the table BRIDGE_CONSTR_ELEMENT. Its schema is analogue to the BRIDGE_INSTALLATION table for the most parts. The relation to the corresponding bridge results from the foreign key BRIDGE_ID. Explicit and implicit geometry or a decomposition through boundary surfaces is possible. Additionally, terrain intersections curves of construction elements can also be stored.
- The OBJECTCLASS_ID column in table BRIDGE_OPENING can be of integer value 79 (BridgeDoor) or 78 (BridgeWindow). They are associated to entries in the table BRIDGE_THEMATIC_SURFACE via the BRIDGE_OPEN_TO_THEM_SRF link table. If a CityGML ADE is used that extends any of the two classes BridgeDoor or BridgeWindow, further values for OBJECTCLASS_ID may be added by the ADE manager. Their concrete numbers depend on the ADE registration (cf. Section 126.96.36.199.1). Like openings of building, bridge openings can have addresses assigned to it.