IfcGeographicElementType

5.4.2.21 IfcGeographicElementType

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'.

Geographic element types includes for many possibilities:

linear elements such as sections of a roadway (including carriageway/pavement, verge, median, marker line, kerb etc.), path, river, stream
connections and junctions including traffic roundabouts, T junctions, 4 way junctions
point features such as street lighting, seating, bus shelters, signage, trees
linear features such as layby's
area features such as ponds, lakes, woods and forests

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 Release IFC2x Edition 4.

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:

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
through use of the IFC classification model whereby features might be identified through a classification notation and additional description; in which case, any further attributes required would still need to be captured in property sets.

EXPRESS Specification

ENTITY IfcGeographicElementType

SUBTYPE OF IfcElementType;

PredefinedType

: IfcGeographicElementTypeEnum;

WHERE

CorrectPredefinedType

: (PredefinedType <> IfcGeographicElementTypeEnum.USERDEFINED) OR ((PredefinedType = IfcGeographicElementTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcElementType.ElementType))

END_ENTITY;

EXPRESS-G Specification

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

ENTITY IfcRoot

GlobalId	: IfcGloballyUniqueId;
OwnerHistory	: OPTIONAL IfcOwnerHistory;
Name	: OPTIONAL IfcLabel;
Description	: OPTIONAL IfcText;

ENTITY IfcObjectDefinition

INVERSE

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;

INVERSE

Types

: SET [0:1] OF IfcRelDefinesByType FOR RelatingType;

ENTITY IfcTypeProduct

RepresentationMaps	: OPTIONAL LIST [1:?] OF IfcRepresentationMap;
Tag	: OPTIONAL IfcLabel;

INVERSE

ReferencedBy

: SET OF IfcRelAssignsToProduct FOR RelatingProduct;

ENTITY IfcElementType

ElementType

: OPTIONAL IfcLabel;

ENTITY IfcGeographicElementType

PredefinedType

: IfcGeographicElementTypeEnum;

END_ENTITY;