IfcGeographicElement

Natural language names
deGeographisches Objekt
enGeographic Element
frElément géographique
Change log
ItemSPFXMLChangeDescription
IFC2x3 to IFC4
    IfcGeographicElementADDED
IFC4 to IFC4 ADD1
    IfcGeographicElement
      HasCoveringsADDED
IFC4x1 to IFC4x2
    IfcGeographicElement
      PositionedFromADDED
Semantic definitions at the entity
Entity definition

An IfcGeographicElement is a generalization of all elements within a geographical landscape. It includes occurrences of typical geographical elements, often referred to as features, such as trees or terrain. Common type information behind several occurrences of IfcGeographicElement is provided by the IfcGeographicElementType.

NOTE  Roads are now represented by IfcCivilElement.
HISTORY  New entity in IFC4.
Attribute definitions
#AttributeTypeCardinalityDescription B
9PredefinedTypeIfcGeographicElementTypeEnum[0:1] Predefined generic types for a geographic element that are specified in an enumeration. There might be property sets defined specifically for each predefined type.X
Formal Propositions
RuleDescription
CorrectPredefinedTypeEither the IfcGeographicElement attribute is unset (e.g. because an IfcGeographicElementType is associated), or the inherited attribute ObjectType shall be provided, if the PredefinedType is set to USERDEFINED.
CorrectTypeAssignedEither there is no geographic element type object associated, i.e. the IsTypedBy inverse relationship is not provided, or the associated type object has to be of type IfcGeographicElementType.
Inherited definitions from supertypes
Entity inheritance IfcElement IfcProduct IfcObject IfcObjectDefinition IfcRoot
Attribute inheritance
#AttributeTypeCardinalityDescriptionB
IfcRoot
1GlobalIdIfcGloballyUniqueId[1:1] Assignment of a globally unique identifier within the entire software world. X
2OwnerHistoryIfcOwnerHistory[0:1] Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object,
NOTE  only the last modification in stored - either as addition, deletion or modification.
X
3NameIfcLabel[0:1] Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule. X
4DescriptionIfcText[0:1] Optional description, provided for exchanging informative comments.X
IfcObjectDefinition
HasAssignmentsIfcRelAssigns
@RelatedObjects		S[0:?]Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups.X
NestsIfcRelNests
@RelatedObjects		S[0:1]References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical strutures only).
IsNestedByIfcRelNests
@RelatingObject		S[0:?]References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types). X
HasContextIfcRelDeclares
@RelatedDefinitions		S[0:1]References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object.
IsDecomposedByIfcRelAggregates
@RelatingObject		S[0:?]References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definitions can be aggregated by several other objects (occurrences or parts). X
DecomposesIfcRelAggregates
@RelatedObjects		S[0:1]References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definitions can only be part of a single decomposition (to allow hierarchical strutures only). X
HasAssociationsIfcRelAssociates
@RelatedObjects		S[0:?]Reference to the relationship objects, that associates external references or other resource definitions to the object.. Examples are the association to library, documentation or classification.X
IfcObject
5ObjectType- This attribute is out of scope for this model view definition and shall not be set.
IsTypedByIfcRelDefinesByType
@RelatedObjects		S[0:1]Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type. X
IsDefinedByIfcRelDefinesByProperties
@RelatedObjects		S[0:?]Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object. X
IfcProduct
6ObjectPlacementIfcObjectPlacement[0:1] Placement of the product in space, the placement can either be absolute (relative to the world coordinate system), relative (relative to the object placement of another product), or constraint (e.g. relative to grid axes). It is determined by the various subtypes of IfcObjectPlacement, which includes the axis placement information to determine the transformation for the object coordinate system.X
7RepresentationIfcProductRepresentation[0:1] Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case a shape representations (IfcProductDefinitionShape). The product definition shape provides for multiple geometric representations of the shape property of the object within the same object coordinate system, defined by the object placement.X
ReferencedByIfcRelAssignsToProduct
@RelatingProduct		S[0:?]Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product.X
IfcElement
8TagIfcIdentifier[0:1] The tag (or label) identifier at the particular instance of a product, e.g. the serial number, or the position number. It is the identifier at the occurrence level.X
ConnectedToIfcRelConnectsElements
@RelatingElement		S[0:?]Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to.
HasOpeningsIfcRelVoidsElement
@RelatingBuildingElement		S[0:?]Reference to the IfcRelVoidsElement relationship that creates an opening in an element. An element can incorporate zero-to-many openings. For each opening, that voids the element, a new relationship IfcRelVoidsElement is generated. X
ConnectedFromIfcRelConnectsElements
@RelatedElement		S[0:?]Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element. X
ContainedInStructureIfcRelContainedInSpatialStructure
@RelatedElements		S[0:1]Containment relationship to the spatial structure element, to which the element is primarily associated. This containment relationship has to be hierachical, i.e. an element may only be assigned directly to zero or one spatial structure.
PositionedFromIfcRelPositions
@RelatingElement		S[0:1]Indicates a constrained placement, where the ObjectPosition must match positioning defined according to the referenced positioning element.X
IfcGeographicElement
9PredefinedTypeIfcGeographicElementTypeEnum[0:1] Predefined generic types for a geographic element that are specified in an enumeration. There might be property sets defined specifically for each predefined type.X
Definitions applying to Bridge View

 Instance diagram

Site grading is indicated using several geometric structures, for which contour lines or the elevation at any point may be derived. This entity may also be used to indicate soil borings at particular points.

Terrain information may be captured using several representations. The “SurveyPoints” representation captures a set of points indicated by IfcCartesianPoint for elevations at arbitrary locations, which may form a rectangular grid or no predefined pattern. This representation also captures breaklines in the form of IfcPolyline indicating elevations that are to be interpolated between points. The “Surface” representation captures the surface using any surface model such as non-uniform rational B-Spline surfaces (NURBS) using IfcBSplineSurface subtypes, a tessellated model using IfcTriangulatedFaceSet, or other geometric constructs.

Soil boring information indicates the position of the test boring with longitudinal and lateral offsets relative to the alignment curve, and classification of soil between elevations for the specified depth of each boring. It is also possible to capture such information using the DIGGS schema, though it may also be beneficial to capture all information within a single file based on a single schema.

Concept usage

Object Typing

The Object Typing concept applies to this entity as shown in Table 18.

Type
IfcGeographicElementType

Table 18 — IfcGeographicElement Object Typing

Exchange
Import O
Export O


Body Tessellation Geometry

The Body Tessellation Geometry concept applies to this entity.

Surface geometry may be represented by tessellation where such mesh faces the upward direction. Surface styles may be applied using a single color for each geometric representation item to distinguish pavement, grass, water, etc.



Material Layer Set With Style

The Material Layer Set With Style concept applies to this entity.

Soil layers are captured using IfcMaterialLayerSet, where the lower and upper elevations of each layer may be determined according to the thickness of each IfcMaterialLayer. Each layer references the corresponding soil type using IfcMaterial, where additional descriptions, properties, and material composition may be defined.

Bridge terrain material

Figure 159 — Bridge terrain material


Concept inheritance

#ConceptModel View
IfcRoot
Software IdentityBridge View
User IdentityBridge View
Object OwnershipBridge View
IfcObject
Property Sets for ObjectsBridge View
IfcElement
Element Occurrence AttributesBridge View
Product Local PlacementBridge View
Product AssignmentBridge View
IfcGeographicElement
Object TypingBridge View
Body Tessellation GeometryBridge View
Material Layer Set With StyleBridge View
Formal representations
XSD Specification
 <xs:element name="IfcGeographicElement" type="ifc:IfcGeographicElement" substitutionGroup="ifc:IfcElement" nillable="true"/>
 <xs:complexType name="IfcGeographicElement">
  <xs:complexContent>
   <xs:extension base="ifc:IfcElement">
    <xs:attribute name="PredefinedType" type="ifc:IfcGeographicElementTypeEnum" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcGeographicElement
 SUBTYPE OF (IfcElement);
  PredefinedType : OPTIONAL IfcGeographicElementTypeEnum;
 WHERE
  CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR (PredefinedType <> IfcGeographicElementTypeEnum.USERDEFINED) OR ((PredefinedType = IfcGeographicElementTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType));
  CorrectTypeAssigned : (SIZEOF(IsTypedBy) = 0) OR ('IFCPRODUCTEXTENSION.IFCGEOGRAPHICELEMENTTYPE' IN TYPEOF(SELF\IfcObject.IsTypedBy[1].RelatingType));
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

Link to this page  Link to this page