Type d'élément géographique
Geographisches Objekt - Typ

An IfcGeographicElementType is used to define an element specification of a geographic element (i.e. the specific product information, that is common to all occurrences of that product type). Geographic element types include for different types of element that may be used to represent information within a geographical landscape external to a building. Within the world of geographic information they are referred to generally as 'features'. IfcGeographicElementType's include:

The specification of the specific types are given by the inherited attribute IfcElementType.ElementType given as an IfcLabel.

NOTE  This is due to the range of choices of element type thyat are available and their expression in different languages. It is not considered possible to create a reasonably full list of types within an enumeration. It is suggested that selection of the relevant type be drawn from an available 'feature catalog'.
HISTORY  New entity in IFC4.

Feature Catalog Use Definition

Geographic element types are frequently identified in feature catalogs that are produced for particular purposes. The IfcGeographicElementType entity enables the continued use of existing feature catalogs through capture of their identity and attributes.

Information from feature catalogs might be captured in various ways:

  1. via property sets, some of which will be specifically defined within the IFC property set catalog whilst others will be created for local use; this is the form of capture that is expected to be most widely used
  2. through use of the IFC classification model whereby features might be identified through an IfcClassificationReference with additional description; in which case, any further attributes required would still need to be captured in property sets.

XSD Specification:

 <xs:element name="IfcGeographicElementType" type="ifc:IfcGeographicElementType" substitutionGroup="ifc:IfcElementType" nillable="true"/>
 <xs:complexType name="IfcGeographicElementType">
   <xs:extension base="ifc:IfcElementType">
    <xs:attribute name="PredefinedType" type="ifc:IfcGeographicElementTypeEnum" use="optional"/>

EXPRESS Specification:

ENTITY IfcGeographicElementType
SUBTYPE OF IfcElementType;
PredefinedType : IfcGeographicElementTypeEnum;
CorrectPredefinedType : (PredefinedType <> IfcGeographicElementTypeEnum.USERDEFINED) OR ((PredefinedType = IfcGeographicElementTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcElementType.ElementType));

Link to EXPRESS-G diagram EXPRESS-G diagram

Attribute Definitions:

PredefinedType : Predefined types to define the particular type of the geographic element. There may be property set definitions available for each predefined type.

Formal Propositions:

CorrectPredefinedType : The inherited attribute ElementType shall be provided, if the PredefinedType is set to USERDEFINED.

Inheritance Graph:

ENTITY IfcGeographicElementType
GlobalId : IfcGloballyUniqueId;
OwnerHistory : OPTIONAL IfcOwnerHistory;
Name : OPTIONAL IfcLabel;
Description : OPTIONAL IfcText;
ENTITY IfcObjectDefinition
HasAssignments : SET OF IfcRelAssigns FOR RelatedObjects;
Nests : SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy : SET OF IfcRelNests FOR RelatingObject;
HasContext : SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy : SET OF IfcRelAggregates FOR RelatingObject;
Decomposes : SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations : SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcTypeObject
ApplicableOccurrence : OPTIONAL IfcIdentifier;
HasPropertySets : OPTIONAL SET [1:?] OF IfcPropertySetDefinition;
Types : SET [0:1] OF IfcRelDefinesByType FOR RelatingType;
ENTITY IfcTypeProduct
RepresentationMaps : OPTIONAL LIST [1:?] OF UNIQUE IfcRepresentationMap;
Tag : OPTIONAL IfcLabel;
ReferencedBy : SET OF IfcRelAssignsToProduct FOR RelatingProduct;
ENTITY IfcElementType
ElementType : OPTIONAL IfcLabel;
ENTITY IfcGeographicElementType
PredefinedType : IfcGeographicElementTypeEnum;

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