IfcRelSpaceBoundary

IfcRelSpaceBoundary

Definition from IAI: The space boundary (IfcRelSpaceBoundary) defines the physical or virtual delimiter of a space as its relationship to the surrounding elements.

In the case of physical space boundary, the placement and shape of the boundary may be given, and the building element, providing the boundary, is referenced,
In the case of virtual space boundary, the placement and shape of the boundary may be given, but no building element is referenced.

The exact definition of how space boundaries are broken down depends on the view, more detailed conventions on how space boundaries are decomposed can only be given at the domain or application type level.

EXAMPLE: In an architectural or FM related view, a space boundary is defined from the inside of the space and does not take the providing building element into account. A plane area (even if the building element changes) is still seen as a single space boundary. In an HVAC related view, the decomposition of the space boundary depends on the material of the providing building element and the adjacent spaces behind.

HISTORY New entity in IFC Release 1.5, the entity has changed in the IFC Release 2x timeframe.
ISSUE See issue and change log for changes made in IFC Release 2x.

The IfcRelSpaceBoundary is defined as an objectified relationship that handles the element to space relationship by objectifying the relationship between an element and the space it bounds. It is given as a one-to-one relationship, but allows each building element to define many such relationship and each space to be defined by many such relationships.

Geometry Use Definitions:

The IfcRelSpaceBoundary may have geometry attached. If geometry is not attached, the relationship between space and building element is handled only on a logical level. If geometry is attached, it is given within the local coordinate systems of the space and (if given in addition) of the building element.

Standard Geometric Representation

The standard geometric representation (through the ConnectionGeometry attribute) is defined using extruded surfaces for space boundaries which bounds prismatic spaces. The following constraints apply to the standard representation:

Surface: IfcSurfaceOfLinearExtrusion
Profile: IfcArbitraryOpenProfileDef
Extrusion: The extrusion direction shall be vertically, i.e., along the positive Z Axis of the co-ordinate system of the containing spatial structure element.

EXPRESS specification:

ENTITY IfcRelSpaceBoundary

SUBTYPE OF (

IfcRelConnects);

RelatingSpace

IfcSpace;

RelatedBuildingElement

OPTIONAL IfcBuildingElement;

ConnectionGeometry

OPTIONAL IfcConnectionSurfaceGeometry;

PhysicalOrVirtualBoundary

IfcPhysicalOrVirtualEnum;

InternalOrExternalBoundary

IfcInternalOrExternalEnum;

WHERE

WR1

((PhysicalOrVirtualBoundary = IfcPhysicalOrVirtualEnum.Physical) AND (EXISTS(RelatedBuildingElement))) OR ((PhysicalOrVirtualBoundary = IfcPhysicalOrVirtualEnum.Virtual) AND (NOT(EXISTS(RelatedBuildingElement)))) OR (PhysicalOrVirtualBoundary = IfcPhysicalOrVirtualEnum.NotDefined);

END_ENTITY;

Attribute definitions:

RelatingSpace	:	Reference to one spaces that is delimited by this boundary.
RelatedBuildingElement	:	Reference to Building Element, that defines the Space Boundaries.
ConnectionGeometry	:	Physical representation of the space boundary. Provided as surface given within the LCS of the space.
PhysicalOrVirtualBoundary	:	Defines, whether the Space Boundary is physical (Physical) or virtual (Virtual).
InternalOrExternalBoundary	:	Defines, whether the Space Boundary is internal (Internal), or external, i.e. adjacent to open space (that can be an partially enclosed space, such as terrace (External).