IfcGeometricRepresentationSubContext

Natural language names
Geometrische Repräsentation - Unterkontext
Geometric Representation Sub Context
Change log
ItemSPFXMLChangeDescription
4.0.1.0
    IfcGeometricRepresentationSubContext
      PrecisionMODIFIEDType changed from REAL to IfcReal.
      HasCoordinateOperationADDED
      PrecisionMODIFIEDType changed from REAL to IfcReal.
Semantic definitions at the entity
Entity definition

IfcGeometricRepresentationSubContext defines the context that applies to several shape representations of a product being a sub context, sharing the WorldCoordinateSystem, CoordinateSpaceDimension, Precision and TrueNorth attributes with the parent IfcGeometricRepresentationContext.

The IfcGeometricRepresentationSubContext is used to define semantically distinguished representation types for different information content, dependent on the representation view and the target scale. It can be used to control the level of detail of the shape representation that is most applicable to this geometric representation context. In addition the sub context is used to control the later appearance of the IfcShapeRepresentation within a plot view.

NOTE  If the IfcShapeRepresentation using this sub context has IfcStyledItem's assigned to the Items, the presentation style information (e.g. IfcCurveStyle, IfcTextStyle) associated with the IfcStyledItem is given in target plot dimensions. For example, a line thickness (IfcCurveStyle.CurveWidth) is given by a thickness measure relating to the thickness for a plot within the (range of) target scale.

Each IfcProduct can then have several instances of subtypes of IfcRepresentation, each being assigned to a different IfcGeometricRepresentationSubContext). The applicable values for the inherited ContextIdentifier attribute shall be identical to the RepresentationIdentifier attrubute defined at IfcShapeRepresentation.

NOTE  The provision of a model view (IfcGeometricRepresentationContext.ContextType = 'Model') is mandatory. Instances of IfcGeometricRepresentationSubContext relate to it as its ParentContext.
EXAMPLE  Instances of IfcGeometricRepresentationSubContext can be used to handle the multi-view blocks or macros, which are used in CAD programs to store several scale and/or view dependent geometric representations of the same object. The application can then choose the most appropriate representation for showing the geometric shape of the product, depending on the target view and scale.
HISTORY  New entity in IFC2x2.
Attribute definitions
#AttributeTypeCardinalityDescription G
7ParentContextIfcGeometricRepresentationContext Parent context from which the sub context derives its world coordinate system, precision, space coordinate dimension and true north.X
8TargetScaleIfcPositiveRatioMeasure? The target plot scale of the representation to which this representation context applies.
NOTE  Scale indicates the target plot scale for the representation sub context, all annotation styles are given in plot dimensions according to this target plot scale.
If multiple instances of IfcGeometricRepresentationSubContext are given having the same TargetView value, the target plot scale applies up to the next smaller scale, or up to unlimited small scale.
NOTE  Scale 1:100 (given as 0.01 within TargetScale) is bigger then 1:200 (given as 0.005 within TargetScale).
X
9TargetViewIfcGeometricProjectionEnum Target view of the representation to which this representation context applies.X
10UserDefinedTargetViewIfcLabel? User defined target view, this attribute value shall be given, if the TargetView attribute is set to USERDEFINED.X
WorldCoordinateSystem
:=ParentContext.WorldCoordinateSystem
IfcAxis2Placement X
CoordinateSpaceDimension
:=ParentContext.CoordinateSpaceDimension
IfcDimensionCount X
TrueNorth
:=NVL(ParentContext.TrueNorth, IfcConvertDirectionInto2D(SELF\IfcGeometricRepresentationContext.WorldCoordinateSystem.P[2]))
IfcDirection X
Precision
:=NVL(ParentContext.Precision,1.E-5)
IfcReal X
Formal Propositions
RuleDescription
ParentNoSubThe parent context shall not be another geometric representation sub context.
UserTargetProvidedThe attribute UserDefinedTargetView shall be given, if the attribute TargetView is set to USERDEFINED.
NoCoordOperationAn IfcCoordinateOperation shall not be provided to a geometric representation sub context, only to the parent geometric representation context.
NOTE  The coordinate operation is used to define the coordinate transformation of the project engineering coordinate system to a geographic coordinate reference system.
Inherited definitions from supertypes
Entity inheritance IfcGeometricRepresentationContext IfcRepresentationContext
Attribute inheritance
#AttributeTypeCardinalityDescriptionG
IfcRepresentationContext
1ContextIdentifierIfcLabel? The optional identifier of the representation context as used within a project.X
2ContextTypeIfcLabel? The description of the type of a representation context. The supported values for context type are to be specified by implementers agreements.X
RepresentationsInContextIfcRepresentation
@ContextOfItems
S[0:?]All shape representations that are defined in the same representation context.X
IfcGeometricRepresentationContext
HasSubContextsIfcGeometricRepresentationSubContext
@ParentContext
S[0:?]The set of IfcGeometricRepresentationSubContexts that refer to this IfcGeometricRepresentationContext.X
HasCoordinateOperationIfcCoordinateOperation
@SourceCRS
S[0:1]Indicates conversion between coordinate systems. In particular it refers to an IfcCoordinateOperation between a Geographic map coordinate reference system, and the engineering coordinate system of this construction project. If there is more then one IfcGeometricRepresentationContext provided to the IfcProject then all contexts shall have an identical instance of IfcCoordinateOperation as HasCoordinateOperation refering to the same instance of IfcCoordinateReferenceSystem. X
IfcGeometricRepresentationSubContext
7ParentContextIfcGeometricRepresentationContext Parent context from which the sub context derives its world coordinate system, precision, space coordinate dimension and true north.X
8TargetScaleIfcPositiveRatioMeasure? The target plot scale of the representation to which this representation context applies.
NOTE  Scale indicates the target plot scale for the representation sub context, all annotation styles are given in plot dimensions according to this target plot scale.
If multiple instances of IfcGeometricRepresentationSubContext are given having the same TargetView value, the target plot scale applies up to the next smaller scale, or up to unlimited small scale.
NOTE  Scale 1:100 (given as 0.01 within TargetScale) is bigger then 1:200 (given as 0.005 within TargetScale).
X
9TargetViewIfcGeometricProjectionEnum Target view of the representation to which this representation context applies.X
10UserDefinedTargetViewIfcLabel? User defined target view, this attribute value shall be given, if the TargetView attribute is set to USERDEFINED.X
WorldCoordinateSystem
:=ParentContext.WorldCoordinateSystem
IfcAxis2Placement X
CoordinateSpaceDimension
:=ParentContext.CoordinateSpaceDimension
IfcDimensionCount X
TrueNorth
:=NVL(ParentContext.TrueNorth, IfcConvertDirectionInto2D(SELF\IfcGeometricRepresentationContext.WorldCoordinateSystem.P[2]))
IfcDirection X
Precision
:=NVL(ParentContext.Precision,1.E-5)
IfcReal X
Formal representations
XML Specification
 <xs:complexType name="IfcGeometricRepresentationSubContext-temp" abstract="true">
  <xs:complexContent>
   <xs:restriction base="ifc:IfcGeometricRepresentationContext">
    <xs:sequence/>
   </xs:restriction>
  </xs:complexContent>
 </xs:complexType>
 <xs:element name="IfcGeometricRepresentationSubContext" type="ifc:IfcGeometricRepresentationSubContext" substitutionGroup="ifc:IfcGeometricRepresentationContext" nillable="true"/>
 <xs:complexType name="IfcGeometricRepresentationSubContext">
  <xs:complexContent>
   <xs:extension base="ifc:IfcGeometricRepresentationSubContext-temp">
    <xs:attribute name="TargetScale" type="ifc:IfcPositiveRatioMeasure" use="optional"/>
    <xs:attribute name="TargetView" type="ifc:IfcGeometricProjectionEnum" use="optional"/>
    <xs:attribute name="UserDefinedTargetView" type="ifc:IfcLabel" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcGeometricRepresentationSubContext
 SUBTYPE OF (IfcGeometricRepresentationContext);
  ParentContext : IfcGeometricRepresentationContext;
  TargetScale : OPTIONAL IfcPositiveRatioMeasure;
  TargetView : IfcGeometricProjectionEnum;
  UserDefinedTargetView : OPTIONAL IfcLabel;
 DERIVE
  SELF\IfcGeometricRepresentationContext.WorldCoordinateSystem : IfcAxis2Placement := ParentContext.WorldCoordinateSystem;
  SELF\IfcGeometricRepresentationContext.CoordinateSpaceDimension : IfcDimensionCount := ParentContext.CoordinateSpaceDimension;
  SELF\IfcGeometricRepresentationContext.TrueNorth : IfcDirection := NVL(ParentContext.TrueNorth, IfcConvertDirectionInto2D(SELF\IfcGeometricRepresentationContext.WorldCoordinateSystem.P[2]));
  SELF\IfcGeometricRepresentationContext.Precision : IfcReal := NVL(ParentContext.Precision,1.E-5);
 WHERE
  ParentNoSub : NOT('IFCREPRESENTATIONRESOURCE.IfcGeometricRepresentationSubContext' IN TYPEOF(ParentContext));
  UserTargetProvided : (TargetView <> IfcGeometricProjectionEnum.USERDEFINED) OR
((TargetView = IfcGeometricProjectionEnum.USERDEFINED) AND EXISTS(UserDefinedTargetView)) ;
  NoCoordOperation : SIZEOF(SELF\IfcGeometricRepresentationContext.HasCoordinateOperation) = 0;
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

References  References: IfcGeometricRepresentationContext

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