IfcShapeRepresentation

Natural language names
deForm - Repräsentation
enShape Representation
frReprésentation de forme
Semantic definitions at the entity
Entity definition

The IfcShapeRepresentation represents the concept of a particular geometric representation of a product or a product component within a specific geometric representation context. The inherited attribute RepresentationType is used to define the geometric model used for the shape representation (e.g. 'SweptSolid', or 'Brep'), the inherited attribute RepresentationIdentifier is used to denote the kind of the representation captured by the IfcShapeRepresentation (e.g. 'Axis', 'Body', etc.).

Several representation identifiers for shape representation are included as predefined values for RepresentationIdentifier. Table 696 indicates the defined list of values for RepresentationIdentifier.

IfcShapeRepresentation表示特定几何表示上下文中产品或产品组件的特定几何表示的概念。继承的属性RepresentationType用于定义用于形状表示的几何模型（例如“SweptSolid”或“Brep”），继承的属性Presentation Identifier用于表示IfcShapeRepresentation捕获的表示类型（例如“Axis”、“Body”等）。
形状表示的几个表示标识符作为表示标识符的预定义值包含在内。表696显示了表示标识符的定义值列表。

Identifier  
CoG Point to identify the center of gravity of an element. This value can be used for validation purposes.(点表示构件的重心。此值可用于验证。)
Box Bounding box as simplified 3D box geometry of an element.(将边界框作为元素的简化三维框几何图形)
Annotation 2D annotations not representing elements.(二维注释不表示元素)
Axis 2D or 3D Axis, or single line, representation of an element.(构件的二维或三维轴或单轴表示)
FootPrint 2D Foot print, or double line, representation of an element, projected to ground view
Profile 3D line representation of a profile being planar, e.g. used for door and window outlines.(平面轮廓的3D线表示，例如用于门窗轮廓)
Surface 3D Surface representation, e.g. of an analytical surface, of an elementplane.(三维曲面，例如元素平面的分析曲面)
Body 3D Body representation, e.g. as wireframe, surface, or solid model, of an element.(三维实体表示，例如元素的线框、曲面或实体模型)
Mesh 3D Body representation, e.g. as tessellation, or other surface, or boundary representation, added in addition to the solid model (potentially involving Boolean operations) of an element.(除了元素的实体模型（可能涉及布尔运算）之外，还添加了3D实体表示，例如镶嵌、其他表面或边界表示)
Clearance 3D clearance volume of the element. Such clearance region indicates space that should not intersect with the 'Body' representation of other elements, though may intersect with the 'Clearance' representation of other elements.(元件的三维间隙体积。此类间隙区域表示不应与其他元素的“主体”表示相交的空间，但可能与其他元素“间隙”表示相交)
Lighting Representation of emitting light as a light source within a shape representation.(作为光源发光的描述元素)

Table 696 — Representation identifiers

Several representation types for shape representation are included as predefined values for RepresentationType. Table 697 indicates the defined list of values for RepresentationType.

Type  
Point 2 or 3 dimensional point(s)(二维或三维点)
PointCloud 3 dimensional points prepresented by a point list.(点云的点，比如.pcd格式)
Curve 2 or 3 dimensional curve(s)(二维或三维曲线)
Curve2D 2 dimensional curve(s)(二维曲线)
Curve3D 3 dimensional curve(s)(三维曲线)
Surface 2 or 3 dimensional surface(s)(二维或三维表面)
Surface2D 2 dimensional surface(s) (a region on ground view)(二维面（地视图上的区域）)
Surface3D 3 dimensional surface(s)(三维表面)
FillArea 2D region(s) represented as a filled area (hatching)(二维区域表示为填充区域（阴影）)
Text text defined as text literals.(定义为文本文字)
AdvancedSurface 3 dimensional b-spline surface(s)
GeometricSet points, curves, surfaces (2 or 3 dimensional)
GeometricCurveSet points, curves (2 or 3 dimensional)(点、曲线（二维或三维）)
Annotation2D points, curves (2 or 3 dimensional), hatches and text (2 dimensional)(点、曲线（二维或三维）、阴影和文本（二维）)
SurfaceModel face based and shell based surface model(s), or tessellated surface model(s)(基于面和基于壳的曲面模型或镶嵌曲面模型)
Tessellation tessellated surface representation(s) only.(仅限镶嵌曲面表示)
SolidModel including swept solid, Boolean results and Brep bodies; more specific types are.(包括扫掠实体、布尔结果和Brep体；更具体的类型有以下类型：)
SweptSolid swept area solids, by extrusion and revolution, excluding tapered sweeps.(通过挤压和旋转得到的扫掠区域固体，不包括锥形扫掠)
AdvancedSweptSolid swept area solids created by sweeping a profile along a directrix, and tapered sweeps.(通过沿准线扫掠轮廓和锥形扫掠创建的扫掠区域实体)
Brep faceted Brep's with and without voids.(带和不带空隙的多面Brep)
AdvancedBrep Brep's based on advanced faces, with b-spline surface geometry, with and without voids.(基于高级面的Brep，具有b样条曲线曲面几何体，有无空洞)
CSG Boolean results of operations between solid models, half spaces and Boolean results.(实体模型、半空间和布尔结果之间运算的布尔结果)
Clipping Boolean differences between swept area solids, half spaces and Boolean results.(扫描区域实体、半空间和布尔结果之间的布尔差异)

additional types
some additional representation types are provided:
BoundingBox simplistic 3D representation by a bounding box.(边界框的简化3D表示)
SectionedSpine cross section based representation of a spine curve and planar cross sections. It can represent a surface or a solid and the interpolations of the between the cross sections is not defined.(基于横截面的脊椎曲线和平面横截面的表示。它可以表示曲面或实体，并且未定义横截面之间的插值)
LightSource light source with (depending on type) position, orientation, light colour, intensity and attenuation.(具有（取决于类型）位置、方向、光色、强度和衰减的光源)
MappedRepresentation representation based on mapped item(s), referring to a representation map. Note: it can be seen as an inserted block reference. The shape representation of the mapped item has a representation type declaring the type of its representation items.(基于映射项的表示，参考表示映射。注意：它可以被视为插入的块参照。映射项的形状表示具有声明其表示项类型的表示类型。)

Table 697 — Representation types
NOTE  The definition relates to shape_representation defined in ISO 10303-41.
HISTORY  New entity in IFC1.5.
IFC4 CHANGE  The RepresentationType's 'Point', 'PointCloud', 'Curve', 'Curve3D', 'Surface', 'Surface2D', 'Surface3D', 'FillArea', 'Text', 'Tessellation', 'AdvancedBrep', 'LightSource', and the RepresentationIdentifier 'Body-FallBack', 'Profile', 'Clearance', 'Lighting' have been added.
Formal Propositions
RuleDescription
CorrectContextThe context to which the IfcShapeRepresentation is assign, shall be of type IfcGeometricRepresentationContext.
NoTopologicalItemNo topological representation item shall be directly used for shape representations, with the exception of IfcVertexPoint, IfcEdgeCurve, IfcFaceSurface.
HasRepresentationTypeA representation type should be provided for the shape representation.
CorrectItemsForTypeChecks the proper use of Items according to the RepresentationType.
HasRepresentationIdentifierA representation identifier should be provided for the shape representation.
Inherited definitions from supertypes
Entity inheritance IfcShapeModel IfcRepresentation
Attribute inheritance
#AttributeTypeCardinalityDescriptionC
IfcRepresentation
1ContextOfItemsIfcRepresentationContext[1:1] Definition of the representation context for which the different subtypes of representation are valid.X
2RepresentationIdentifierIfcLabel[0:1] The optional identifier of the representation as used within a project.X
3RepresentationTypeIfcLabel[0:1] The description of the type of a representation context. The representation type defines the type of geometry or topology used for representing the product representation. More information is given at the subtypes IfcShapeRepresentation and IfcTopologyRepresentation.
The supported values for context type are to be specified by implementers agreements. 		X
4ItemsIfcRepresentationItemS[1:?] Set of geometric representation items that are defined for this representation.X
RepresentationMapIfcRepresentationMap
@MappedRepresentation		S[0:1]Use of the representation within an IfcRepresentationMap. If used, this IfcRepresentation may be assigned to many representations as one of its Items using an IfcMappedItem. Using IfcRepresentationMap is the way to share one representation (often of type IfcShapeRepresentation) by many products. X
LayerAssignmentsIfcPresentationLayerAssignment
@AssignedItems		S[0:?]Assignment of the whole representation to a single or multiple layer(s). The LayerAssigments can be overridden by LayerAssigments of the IfcRepresentationItem's within the list of Items.
NOTE  Implementation agreements can restrict the maximum number of layer assignments to 1.
X
OfProductRepresentationIfcProductRepresentation
@Representations		S[0:?]Reference to the product representations to which this individual representation applies. In most cases it is the reference to one or many product shapes, to which this shape representation is applicable. X
IfcShapeModel
OfShapeAspectIfcShapeAspect
@ShapeRepresentations		S[0:1]Reference to the shape aspect, for which it is the shape representation.X
IfcShapeRepresentation
Examples
Formal representations
XSD Specification
 <xs:element name="IfcShapeRepresentation" type="ifc:IfcShapeRepresentation" substitutionGroup="ifc:IfcShapeModel" nillable="true"/>
 <xs:complexType name="IfcShapeRepresentation">
  <xs:complexContent>
   <xs:extension base="ifc:IfcShapeModel"/>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcShapeRepresentation
 SUBTYPE OF (IfcShapeModel);
 WHERE
  CorrectContext : 'IFCREPRESENTATIONRESOURCE.IFCGEOMETRICREPRESENTATIONCONTEXT' IN TYPEOF(SELF\IfcRepresentation.ContextOfItems);
  NoTopologicalItem : SIZEOF(QUERY(temp <* Items | ('IFCTOPOLOGYRESOURCE.IFCTOPOLOGICALREPRESENTATIONITEM' IN TYPEOF(temp)) AND (NOT(SIZEOF( ['IFCTOPOLOGYRESOURCE.IFCVERTEXPOINT', 'IFCTOPOLOGYRESOURCE.IFCEDGECURVE', 'IFCTOPOLOGYRESOURCE.IFCFACESURFACE'] * TYPEOF(temp)) = 1)) )) = 0;
  HasRepresentationType : EXISTS(SELF\IfcRepresentation.RepresentationType);
  CorrectItemsForType : IfcShapeRepresentationTypes(SELF\IfcRepresentation.RepresentationType, SELF\IfcRepresentation.Items);
  HasRepresentationIdentifier : EXISTS(SELF\IfcRepresentation.RepresentationIdentifier);
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

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