IFC (IFC4X3) development

8.7 IfcGeometricConstraintResource

8.7.1 Schema definition

The schema IfcGeometricConstraintResource defines the resources used to determine the placement of the shape representation of a product within the geometric representation context of a project. It also contains resource definitions to be assigned to product connectivity definitions to determine the connection geometry constraints between those products.

The primary application of this resource is to:

  • determine the object placement used for the shape representation of the object
  • determine the constraints applied to the connectivity between two shapes of objects Placement

The placement of an product's shape is given by the IfcObjectPlacement, used by the attribute ObjectPlacement of IfcProduct. The object placement defines the local object coordinate system in which all shape representations of that product are defined. It is given either as

  • absolute placement,
    • the absolute placement is specified by using IfcLocalPlacement and omitting the PlacementRelTo attribute;
  • relative placement,
  • placement relative to a grid,
    • the placement relative to a grid is specified by using IfcGridPlacement pointing to one (or two) virtual intersections of IfcGridAxis. If two virtual intersections are references, than the second virtual intersections specifies the orientation of the object placement. Alternatively the direction can also be provided explicitly by ifcDirection. Connection geometry

The connection geometry defines the connectivity between the shapes of two products. The constraint can be defined by geometric representation items:

  • point
  • curve
  • surface
  • solid

or by topological representation items with associated geometry:

  • vertex point
  • edge curve
  • face surface
  • closed shell

As a special type of point connection includes the provision to express an eccentricity, i.e. a physical distance between the two points involved in the connection.

8.7.2 Types

  1. IfcAlignmentCantSegmentTypeEnum
  2. IfcAlignmentHorizontalSegmentTypeEnum
  3. IfcAlignmentVerticalSegmentTypeEnum
  4. IfcCurveOrEdgeCurve
  5. IfcGridPlacementDirectionSelect
  6. IfcPointOrVertexPoint
  7. IfcSolidOrShell
  8. IfcSurfaceOrFaceSurface

8.7.3 Entities

  1. IfcAlignmentCantSegment
  2. IfcAlignmentHorizontalSegment
  3. IfcAlignmentParameterSegment
  4. IfcAlignmentVerticalSegment
  5. IfcConnectionCurveGeometry
  6. IfcConnectionGeometry
  7. IfcConnectionPointEccentricity
  8. IfcConnectionPointGeometry
  9. IfcConnectionSurfaceGeometry
  10. IfcConnectionVolumeGeometry
  11. IfcGridAxis
  12. IfcGridPlacement
  13. IfcLinearPlacement
  14. IfcLocalPlacement
  15. IfcObjectPlacement
  16. IfcVirtualGridIntersection

8.7.4 Property Sets

No resources are available in this category.

8.7.5 Quantity Sets

No resources are available in this category.

8.7.6 Functions

  1. IfcCorrectLocalPlacement

8.7.7 Rules

No resources are available in this category.

8.7.8 PropertyEnumerations

No resources are available in this category.

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