Definition from IAI: Definition for any element which covers some
part of another element and is fully dependent on that other element.
EXAMPLEs include wall, floor and ceiling coverings,
finish trim, and base molding.
Coverings can be assigned to either a space boundary, using the inverse
relationship ProvidesBoundaries pointing to IfcRelSpaceBoundary,
or to a building element, using the inverse relationship Covers pointing
to IfcRelCoversBldgElements. The following guideline shall apply:
- if the space has defined space boundaries, then the covering, which
relates to that space, should be assigned to the space boundaries
- if the space has no space boundaries defined, or the covering does
not relate to a space, then the covering should be assigned to the building
element
The quantities relating to the covering are defined by the
IfcElementQuantity and attached by the IfcRelDefinesByProperties.
The following quantities are foreseen, but will be subjected to the local
standard of measurement:
| Name |
Description |
Value
Type |
| CoveredArea |
Total area of
the covering in the elevation view. The exact definition and calculation rules
depend on the method of measurement used. |
IfcAreaQuantity |
HISTORY New entity in IFC
Release 1.0
ISSUE See issue log for changes made in IFC Release 1.5. and
1.5.1. See issue and change log for changes made in IFC Release 2x.
Geometry Use Definitions
The geometric representation of IfcCovering is given by the
IfcProductDefinitionShape, allowing multiple geometric representation.
Included are:
Local Placement
The local placement for IfcCovering is defined in its supertype
IfcProduct. It is defined by the IfcLocalPlacement, which defines the local
coordinate system that is referenced by all geometric representations.
- The PlacementRelTo relationship of IfcLocalPlacement shall point (if
given) to the same IfcSpatialStructureElement , which is used in the
ContainedInStructure inverse attribute, or to a spatial structure element at a
higher level, referenced by that.
- If the IfcCovering, however, is assigned to an IfcBuildingElement,
and this element defines its own local placement, than the PlacementRelTo
relationship of IfcLocalPlacement shall point (if given) to the local placement
of the IfcBuildingElement.
- If the relative placement is not used, the absolute placement is
defined within the world coordinate system.
Geometric Representation
The geometric representation of the IfcCovering depends on two
criteria:
- Does it define an area or a volume?
- Is the base surface (either the IfcSpaceBoundary or the surface of
the IfcBuildingElement it relates to) a planar surface or a cylindrical
surface?
Standard Geometric Representation using Bounded Surface and Swept
Surface Representation
The standard geometric representation of IfcCovering supports area
definitions as 3D surfaces. The standard geometric representation of
IfcCovering is defined using the following representation types:
- for planar base surfaces - bounded surface representation
- for cylindrical base surfaces - swept surface representation
EXAMPLE for standard geometric representation.
 |
The area of IfcCovering is given by an
IfcPolyloop for planar base surfaces (here given by the IfcSpaceBoundary).
- The implicit planar surface of the IfcPolyloop
shall be identical with the planar surface defined by the
IfcSpaceBoundary.
|
 |
The area of the IfcCovering is given by
an IfcSurfaceOfLinearExtrusion for cylindrical base surfaces (here given by the
IfcSpaceBoundary - e.g. caused by a round wall).
- The geometry representation of the IfcCovering
is given by the IfcTrimmedCurved (the Curve parameter of the
IfcArbitraryOpenProfileDef - in cases of faceted representation also an
IfcPolyline). It is extruded within the plane of the base surface using the
Depth parameter of the IfcSurfaceOfLinearExtrusion.
|
Advanced Geometric Representation using Swept Solid
Representation
The advanced geometric representation of IfcCovering supports volume
definitions as 3D solids. The advanced geometric representation of IfcCovering
is defined using the following representation types:
- for planar base surfaces - swept area representation
- for cylindrical base surfaces - swept area representation
EXAMPLE for advanced geometric representation.
 |
The volume of IfcCovering is given by an
IfcExtrudedAreaSolid for planar base surfaces (here given by the
IfcSpaceBoundary).
- The extruded area (IfcArbitraryProfileDef)
shall be coplanar to the surface defined by the IfcSpaceBoundary.
|
 |
The volume of the IfcCovering is given by
an IfcExtrudedAreaSolid for cylindrical base surfaces (here given by the
IfcSpaceBoundary - e.g. caused by a round wall).
- The geometry representation of the IfcCovering
is given by the Ifc2DCompositeCurve (the OuterCurve parameter of the
IfcArbitraryProfileDef - in cases of faceted representation also a closed
IfcPolyline). It is extruded along the plane of the base surface using the
Depth parameter of the IfcSurfaceOfLinearExtrusion.
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EXPRESS specification:
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|
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|
| WR1
|
:
|
SIZEOF (QUERY(temp <* SELF\IfcObject.HasAssociations |
'IFCPRODUCTEXTENSION.IFCRELASSOCIATESMATERIAL' IN TYPEOF(temp)
)) <= 1;
|
| WR2
|
:
|
(PredefinedType <> IfcCoveringTypeEnum.UserDefined) OR
((PredefinedType = IfcCoveringTypeEnum.UserDefined) AND EXISTS(SELF\IfcObject.ObjectType));
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Attribute definitions:
| PredefinedType
|
:
|
Predefined types to define the particular type of the covering. There may be property set definitions
available for each predefined type.
|
| Covers
|
:
|
Reference to the objectified relationship that handles the relationship of the Covering to the covered
Building Element.
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Formal Propositions:
| WR1
|
:
|
There shall be only maximum one material association for covering.
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| WR2
|
:
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The attribute UserDefinedType shall be given, if the predefined type is set to USERDEFINED.
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References (2):
Inheritance graph
