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8.18.3.11 IfcProjectedCRS

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AbV ⓘ

8.18.3.11.1 Semantic definition

IfcProjectedCRS is a coordinate reference system (CRS) of the map to which the map translation of the local engineering coordinate system of the construction or facility engineering project relates. The projected coordinate reference system is assumed to be a 2D or 3D right-handed Cartesian coordinate system, the optional MapUnit attribute can be used to determine the length unit used by the map.

Despite what its name suggests:

The unambiguous identifier by which the coordinate reference system is known, is stored in the inherited Name attribute. Well defined identifiers include the map projection, the map zone information, and all required datums. In these cases the attributes VerticalDatum, MapProjection, MapZone as well as the inherited attribute GeodeticDatum can be omitted.

8.18.3.11.2 Entity inheritance

8.18.3.11.3 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.

Click to show 5 hidden inherited attributes Click to hide 5 inherited attributes
IfcProjectedCRS (4)
4 VerticalDatum OPTIONAL IfcIdentifier

Name by which the vertical datum is identified. The vertical datum is associated with the height axis of the coordinate reference system and indicates the reference plane and fundamental point defining the origin of a height system. It needs to be provided, if the Name identifier does not unambiguously define the vertical datum as well and if the coordinate reference system is a 3D reference system.

5 MapProjection OPTIONAL IfcIdentifier

Name by which the map projection is identified.

6 MapZone OPTIONAL IfcIdentifier

Name by which the map zone, relating to the MapProjection, is identified.

7 MapUnit OPTIONAL IfcNamedUnit

Unit of the coordinate axes composing the map coordinate system.

Table 8.18.3.11.D

8.18.3.11.4 Formal propositions

Name Description
MapUnitIsLength

No description available.

NOT(EXISTS(SELF.MapUnit)) OR (SELF.MapUnit.UnitType = IfcUnitEnum.LENGTHUNIT)
Table 8.18.3.11.E

8.18.3.11.5 Examples

8.18.3.11.6 Formal representation

ENTITY IfcProjectedCRS
 SUBTYPE OF (IfcCoordinateReferenceSystem);
	VerticalDatum : OPTIONAL IfcIdentifier;
	MapProjection : OPTIONAL IfcIdentifier;
	MapZone : OPTIONAL IfcIdentifier;
	MapUnit : OPTIONAL IfcNamedUnit;
 WHERE
	MapUnitIsLength : NOT(EXISTS(SELF.MapUnit)) OR (SELF.MapUnit.UnitType = IfcUnitEnum.LENGTHUNIT);
END_ENTITY;

8.18.3.11.7 References

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8.18.3.11.8 Changelog

8.18.3.11.8.1 IFC4

  • New resource

8.18.3.11.8.2 IFC4.3_DEV_4b16bd1

  • attribute, VerticalDatum
  • where rule, MapUnitIsLength
  • where rule, IsLengthUnit