IfcRelSpaceBoundary
IfcRelSpaceBoundary
实体定义
空间边界通过IfcRelSpaceBoundary与周围元素的关系来定义空间的物理或虚拟分隔符。
在物理空间边界的情况下，可以给出边界的位置和形状，并且参考提供边界的建筑元素，
在虚拟空间边界的情况下，可以给出边界的位置和形状，并且参考虚拟元素。
IfcRelSpaceBoundary被定义为一种对象化关系，通过对象化元素与其边界空间之间的关系来处理元素与空间的关系。它是以一对一的关系给出的，但允许每个元素（包括虚拟元素和开口）定义许多这样的关系，并允许每个空间由许多这种关系定义。
空间边界始终定义为从空间中看到的边界。通常区分两种基本类型的空间边界：
一级空间边界：定义为空间的边界，不考虑另一侧建筑元素或空间的任何变化。
二级空间边界：定义为考虑到另一侧建筑元素或空间的任何变化的边界。它可以进一步区分为
二级A类：另一侧有一个空位。
第二层类型B：在另一侧有一个建筑元素。
如何分解空间边界的确切定义取决于视图定义，关于如何分解空间界限的更详细约定只能在域或应用程序类型级别给出。
在建筑或FM相关视图中，空间边界完全是从空间内部定义的。这是一级空间边界。
在热视图中，空间边界的分解取决于提供建筑元件的材料和后面的相邻空间。这是一个二级空间边界。
图：-一级空间边界
图：二级空间边界
图——A类二级空间边界
图-B类二级空间边界
一级和二级空间边界之间的差异通过以下方式确定：
- 1st level:
SELF\IfcRoot.Name = "1stLevel"
SELF\IfcRootDescription = NIL - 2nd level:
SELF\IfcRoot.Name = "2ndLevel"
SELF\IfcRootDescription = "2a", or "2b"
物理和虚拟空间边界之间的区别如图162和图42所示。
如图41所示，如果IfcRelSpaceBoundary用于表示虚拟边界，则必须将属性PhysicalOrVirtualBoundary设置为virtual。RelatedBuildingElement属性应指向IfcVirtualElement的一个实例。如果感兴趣的是正确的位置，则需要属性ConnectionGeometry。
注：通过2D曲线或3D表面的连接几何图形用于描述分隔两个空间的“虚拟墙”部分。在相邻空间给定的IfcRelSpaceBoundary的所有实例共享IfcVirtualElement的相同实例。IfcRelSpaceBoundary的每个实例还提供了在每个空间的局部放置中给定的ConnectionGeometry。
图——虚拟元素的空间边界
如图所示，如果IfcRelSpaceBoundary用于表示两个空间之间的物理边界，则必须将属性PhysicalOrVirtualBoundary设置为physical。必须给定RelatedBuildingElement属性，并指向提供空间边界的元素。属性ConnectionGeometry可以插入，在这种情况下，它以几何方式描述物理空间边界，也可以省略，在这种情形下，它逻辑地描述物理空间界限。
图-物理元素的空间边界
IfcRelSpaceBoundary可能已附加几何体。如果未附着几何图形，则仅在逻辑级别上处理空间和建筑图元之间的关系。如果附着了几何图形，则该几何图形将在空间的局部坐标系中给定。
注：IfcConnectionCurveGeometry处的CurveOnRelatingElement或IfcConnectionSurfaceGeometry的SurfaceOnRelatingElement属性提供了IfcSpace的局部坐标系内的几何体，而IfcConnectionCurveGeometry处的CurveOnRelatedElement或IfcConnectionSurfaceGeometry的SurfaceOnRelatedElements属性提供IfcElement子类型的局部坐标系内的几何体
注：在大多数视图定义中，未提供相关IfcElement的连接几何图形。
几何表示（通过ConnectionGeometry属性）是使用空间边界的二维曲线几何图形或三维曲面几何图形定义的。在大多数视图定义中，都需要三维连接曲面几何图形。
一级空间边界：
应仅提供相关空间的连接几何形状
仅应提供表面连接几何形状
仅支持以下曲面表示：
二级空间边界：
应仅提供相关空间的连接几何形状
仅应提供表面连接几何形状
仅支持以下曲面表示：
- IfcCurveBoundedPlane with restrictions to have polygonal boundaries only
- IfcFaceBasedSurfaceModel
表面连接几何图形
以下约束适用于曲面连接几何图形表达：
平面边界：
- IfcSurfaceOfLinearExtrusion defined by a SweptCurve being an IfcArbitraryOpenProfileDef with straight segements, or
- IfcCurveBoundedPlane
弯曲边界
- IfcSurfaceOfLinearExtrusion defined by a SweptCurve being an IfcArbitraryOpenProfileDef with curves segements, or
- IfcCurveBoundedSurface with a BasisSurface being a non planar surface, such as IfcCylindricalSurface, or
- IfcFaceBasedSurfaceModel if already faceted.
曲线连接几何图形
以下约束适用于二维曲线表示：
曲线：IfcPolyline、IfcTrimmedCCurve或IfcCompositeCurve
IFC1.5中的新实体，该实体已在IFC2x中修改。
IFC2x 修改属性RelatedBuildingElement的数据类型已从IfcBuildingElement更改为其超类型IfcElement。属性ConnectionGeometry的数据类型已从IfcConnectionSurfaceGeometry更改为其超类型IfcConnectionGeometry。
IFC4 修改属性RelatedBuildingElement已被强制设置。对于虚拟边界，现在必须引用IfcVirtualElement。
Attribute definitions
| # | Attribute | Type | Cardinality | Description | C |
|---|---|---|---|---|---|
| 5 | RelatingSpace | IfcSpaceBoundarySelect | [1:1] | Reference to one spaces that is delimited by this boundary. | X |
| 6 | RelatedBuildingElement | IfcElement | [1:1] | Reference to Building Element, that defines the Space Boundaries. | X |
| 7 | ConnectionGeometry | IfcConnectionGeometry | [0:1] | Physical representation of the space boundary. Provided as a curve or surface given within the LCS of the space. | X |
| 8 | PhysicalOrVirtualBoundary | IfcPhysicalOrVirtualEnum | [1:1] | Defines, whether the Space Boundary is physical (Physical) or virtual (Virtual). | X |
| 9 | InternalOrExternalBoundary | IfcInternalOrExternalEnum | [1:1] | 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). | X |
Formal Propositions
| Rule | Description |
|---|---|
| CorrectPhysOrVirt | If the space boundary is physical, it shall be provided by an element (i.e. excluding a virtual element). If the space boundary is virtual, it shall either have a virtual element or an opening providing the space boundary. If the space boundary PhysicalOrVirtualBoundary attribute is not defined, no restrictions are imposed.
IFC4 CHANGE Where rule corrected to accept an IfcOpeningElement for a virtual space boundary. |
Attribute inheritance
| # | Attribute | Type | Cardinality | Description | C |
|---|---|---|---|---|---|
| IfcRoot | |||||
| 1 | GlobalId | IfcGloballyUniqueId | [1:1] | Assignment of a globally unique identifier within the entire software world. | X |
| 2 | OwnerHistory | IfcOwnerHistory | [0:1] | Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object,
NOTE only the last modification in stored - either as addition, deletion or modification. |
X |
| 3 | Name | IfcLabel | [0:1] | Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule. | X |
| 4 | Description | IfcText | [0:1] | Optional description, provided for exchanging informative comments. | X |
| IfcRelationship | |||||
| IfcRelConnects | |||||
| IfcRelSpaceBoundary | |||||
| 5 | RelatingSpace | IfcSpaceBoundarySelect | [1:1] | Reference to one spaces that is delimited by this boundary. | X |
| 6 | RelatedBuildingElement | IfcElement | [1:1] | Reference to Building Element, that defines the Space Boundaries. | X |
| 7 | ConnectionGeometry | IfcConnectionGeometry | [0:1] | Physical representation of the space boundary. Provided as a curve or surface given within the LCS of the space. | X |
| 8 | PhysicalOrVirtualBoundary | IfcPhysicalOrVirtualEnum | [1:1] | Defines, whether the Space Boundary is physical (Physical) or virtual (Virtual). | X |
| 9 | InternalOrExternalBoundary | IfcInternalOrExternalEnum | [1:1] | 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). | X |
EXPRESS Specification
ENTITY IfcRelSpaceBoundary
SUPERTYPE OF(IfcRelSpaceBoundary1stLevel)
SUBTYPE OF (IfcRelConnects);
RelatingSpace : IfcSpaceBoundarySelect;
RelatedBuildingElement : IfcElement;
ConnectionGeometry : OPTIONAL IfcConnectionGeometry;
PhysicalOrVirtualBoundary : IfcPhysicalOrVirtualEnum;
InternalOrExternalBoundary : IfcInternalOrExternalEnum;
WHERE
CorrectPhysOrVirt : ((PhysicalOrVirtualBoundary = IfcPhysicalOrVirtualEnum.Physical) AND (NOT('IFCPRODUCTEXTENSION.IFCVIRTUALELEMENT' IN TYPEOF(RelatedBuildingElement)))) OR ((PhysicalOrVirtualBoundary = IfcPhysicalOrVirtualEnum.Virtual) AND (('IFCPRODUCTEXTENSION.IFCVIRTUALELEMENT' IN TYPEOF(RelatedBuildingElement)) OR ('IFCPRODUCTEXTENSION.IFCOPENINGELEMENT' IN TYPEOF(RelatedBuildingElement)))) OR (PhysicalOrVirtualBoundary = IfcPhysicalOrVirtualEnum.NotDefined);
END_ENTITY;
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