Géoréférencement IFC

Le schéma suivant illustre les entités IFC et les relations liées au géoréférencement d’un modèle IFC4. On considère que la relation spatiale entre les entités IfcSite, IfcBuilding, IfcBuildingStorey est de type hiérarchique.

graph TD
  A[IfcProject] -->|RepresentationContexts| B[IfcGeometricRepresentationContext]
  B -->|WorldCoordinateSystem| C[IfcAxis2Placement3D]
  C -->|Location| C1["(0, 0, 0)<br/>Local origin"]
  C -->|Axis| C2["(0, 0, 1)<br/>Z axis vertical"]
  C -->|RefDirection| C3["(1, 0, 0)<br/>X axis"]
  
  B -->|TrueNorth| B1["North direction vector<br/>(optional if IfcMapConversion exists)<br/>e.g.: (0, 1) without rotation"]
  
  B -->|HasCoordinateOperation| D[IfcMapConversion]
  D -->|SourceCRS<br/>relation inverse| B
  D -->|TargetCRS| E[IfcProjectedCRS]
  E -->|Name| E1["EPSG:2154<br/>Lambert 93"]
  
  D -->|Parameters| D1["Eastings: 500000<br/>Northings: 6000000<br/>OrthogonalHeight: 50<br/>XAxisAbscissa: 1.0<br/>XAxisOrdinate: 0.0<br/>Scale: 1.0"]
  
  A -->|Contains| F[IfcSite]
  C -->|PlacementRelTo| F
  F -->|IfcLocalPlacement| F1["RelativePlacement<br/>(10, 20, 0)<br/>relative to WorldCoordinateSystem<br/>PlacementRelTo = NULL = absolute"]
  F -->|Geographic attributes| F2["RefLatitude: 48.8566<br/>RefLongitude: 2.3522<br/>RefElevation: 50<br/>(reference data)"]
  
  F -->|Contains| G[IfcBuilding]
  G -->|IfcLocalPlacement| G1["RelativePlacement<br/>(5, 5, 0)<br/>relative to IfcSite"]
  G -->|Elevation attributes| G2["ElevationOfRefHeight: 54<br/>(absolute elevation of ±0.00)<br/>ElevationOfTerrain: 50<br/>(elevation of terrain at perimeter)"]
  
  G -->|Contains| H[IfcBuildingStorey]
  H -->|IfcLocalPlacement| H1["RelativePlacement<br/>(0, 0, 3.5)<br/>relative to IfcBuilding"]
  H -->|Elevation| H2["3.5"]
  
  H -->|Contains| I[IfcElement<br/>Wall, Slab, etc.]
  I -->|IfcLocalPlacement| I1["RelativePlacement<br/>relative to IfcStorey"]
  
  style A fill:#2196f3
  style B fill:#ff9800
  style D fill:#4caf50
  style E fill:#4caf50
  style F fill:#e91e63
  style G fill:#e91e63
  style H fill:#e91e63
  style I fill:#e91e63
  style C fill:#ff9800
  style D1 fill:#4caf50
  style B1 fill:#ff9800
  
  subgraph "Project coordinate system"
    B
    B1
    C
    C1
    C2
    C3
  end
  
  subgraph "Georeferencing"
    D
    D1
    E
    E1
  end
  
  subgraph "Spatial hierarchy"
    F
    F1
    F2
    G
    G1
    G2
    H
    H1
    H2
    I
    I1
  end