IFC (IFC4X3_ADD2) under development IfcCoordinateReferenceSystem

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ABSTRACT This definition may not be instantiated Semantic definition

The IfcCoordinateReferenceSystem is a definition of a coordinate reference system by means of qualified identifiers only. The interpretation of the identifier is expected to be well-known to the receiving software.

The unambiguous identifier by which the coordinate reference system is know, is stored in the Name attribute. Well defined identifiers include the geodetic and the vertical CRS, each with its own datum. In these cases the GeodeticDatum can be omitted. Entity inheritance Attributes

# Attribute Type Description
IfcCoordinateReferenceSystem (5)
1 Name OPTIONAL IfcLabel

Name by which the coordinate reference system is identified.

2 Description OPTIONAL IfcText

Informal description of this coordinate reference system.

3 GeodeticDatum OPTIONAL IfcIdentifier

Name by which this datum is identified. The geodetic datum is associated with the coordinate reference system and indicates the shape and size of the rotation ellipsoid and this ellipsoid's connection and orientation to the actual globe/earth. It needs to be provided, if the Name identifier does not unambiguously define the geodetic datum as well.

HasCoordinateOperation SET [0:1] OF IfcCoordinateOperation FOR SourceCRS

Indicates conversion between coordinate reference systems. In particular it refers to an IfcCoordinateOperation between this coordinate reference system, and another coordinate reference system.

WellKnownText SET [0:1] OF IfcWellKnownText FOR CoordinateReferenceSystem

Well Known Text (WKT) definition for this coordinate reference system inversely associated as a IfcWellKnownText entity.

Table Formal propositions

Name Description

Ensures that the coordinate reference system is properly specified by either a reference to an EPSG code in Name or a well known text in WellKnownText.

(HIINDEX(WellKnownText) = 1) OR EXISTS(Name)
Table Formal representation

ENTITY IfcCoordinateReferenceSystem
	Name : OPTIONAL IfcLabel;
	Description : OPTIONAL IfcText;
	GeodeticDatum : OPTIONAL IfcIdentifier;
	HasCoordinateOperation : SET [0:1] OF IfcCoordinateOperation FOR SourceCRS;
	WellKnownText : SET [0:1] OF IfcWellKnownText FOR CoordinateReferenceSystem;
	NameOrWKT : (HIINDEX(WellKnownText) = 1) OR EXISTS(Name);
END_ENTITY; References

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Is this page difficult to understand? Let us know! Changelog IFC4

  • New resource IFC4.3_DEV_ffe3a63

  • inverse attribute, WellKnownText
  • where rule, NameOrWKT
  • attribute, VerticalDatum
  • attribute Name optional, Is now optional