| # | Attribute | Type | Cardinality | Description | G |
|---|---|---|---|---|---|
| 4 | PrimeMeridian | IfcIdentifier | ? | The identification of the meridian defining zero longitude in the used geographic CRS. | X |
| 5 | AngleUnit | IfcNamedUnit | ? |
Unit of latitude and longitude coordinate axes composing the geographic coordinate system.
NOTE Only plane angle measures are in scope and both longitude and latitude coordinate axes of the geographic coordinate system shall have the same plane angle unit. NOTE If AngleUnit is omitted, the unit for latitude and longitude coordinate axes is taken from the default project angle units, as stated in IfcProject.UnitsInContext. | X |
| 6 | HeightUnit | IfcNamedUnit | ? |
Unit of the height coordinate axis of the geographic coordinate system.
NOTE Only length measures are in scope. NOTE If HeightUnit is omitted, the unit for the height coordinate axis is taken from the default project length units, as stated in IfcProject.UnitsInContext. | X |
| Rule | Description |
|---|---|
| AngleUnitIsPlaneAngle | The type of AngleUnit in the operation shall be IfcUnitEnum.PLANEANGLEUNIT. |
| HeightUnitIsLength | The type of HeightUnit in the operation shall be IfcUnitEnum.LENGTHUNIT. |
| # | Attribute | Type | Cardinality | Description | G |
|---|---|---|---|---|---|
| IfcCoordinateReferenceSystem | |||||
| 1 | Name | IfcLabel | ? |
Name by which the coordinate reference system is identified.
NOTE 1 The name shall be taken from the list recognized by the European Petroleum Survey Group EPSG. It should then be qualified by the EPSG name space, for example as 'EPSG:5555'. NOTE 2 The name shall be 'WKT' if an EPSG code does not exist for the CRS. | X |
| 2 | Description | IfcText | ? |
Informal description of this coordinate reference system
NOTE In case Name equals 'WKT' the Description is well-known text that corresponds to ISO 19162 definition specifying the necessary parameters for the coordinate reference system. Example for ellipsoid: ELLIPSOID[<name>,<major axis>,<inverse flattening>,<length unit>] | X |
| 3 | GeodeticDatum | 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.
EXAMPLE geodetic datums include: | X |
| HasCoordinateOperation | IfcCoordinateOperation @SourceCRS | S[0:1] | Indicates conversion between coordinate systems. In particular it refers to an IfcCoordinateOperation between this coordinate reference system, and another Geographic coordinate reference system. | X | |
| WellKnownText | IfcWellKnownText @CoordinateReferenceSystem | S[0:1] | Well Known Text (WKT) definition for this coordinate reference system inversely associated as a IfcWellKnownText entity. | X | |
| IfcGeographicCRS | |||||
| 4 | PrimeMeridian | IfcIdentifier | ? | The identification of the meridian defining zero longitude in the used geographic CRS. | X |
| 5 | AngleUnit | IfcNamedUnit | ? |
Unit of latitude and longitude coordinate axes composing the geographic coordinate system.
NOTE Only plane angle measures are in scope and both longitude and latitude coordinate axes of the geographic coordinate system shall have the same plane angle unit. NOTE If AngleUnit is omitted, the unit for latitude and longitude coordinate axes is taken from the default project angle units, as stated in IfcProject.UnitsInContext. | X |
| 6 | HeightUnit | IfcNamedUnit | ? |
Unit of the height coordinate axis of the geographic coordinate system.
NOTE Only length measures are in scope. NOTE If HeightUnit is omitted, the unit for the height coordinate axis is taken from the default project length units, as stated in IfcProject.UnitsInContext. | X |
<xs:element name="IfcGeographicCRS" type="ifc:IfcGeographicCRS" substitutionGroup="ifc:IfcCoordinateReferenceSystem" nillable="true"/>
<xs:complexType name="IfcGeographicCRS">
<xs:complexContent>
<xs:extension base="ifc:IfcCoordinateReferenceSystem">
<xs:sequence>
<xs:element name="AngleUnit" type="ifc:IfcNamedUnit" nillable="true" minOccurs="0"/>
<xs:element name="HeightUnit" type="ifc:IfcNamedUnit" nillable="true" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="PrimeMeridian" type="ifc:IfcIdentifier" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
ENTITY IfcGeographicCRS
SUBTYPE OF (IfcCoordinateReferenceSystem);
PrimeMeridian : OPTIONAL IfcIdentifier;
AngleUnit : OPTIONAL IfcNamedUnit;
HeightUnit : OPTIONAL IfcNamedUnit;
WHERE
AngleUnitIsPlaneAngle : NOT(EXISTS(SELF.AngleUnit)) OR (SELF.AngleUnit.UnitType=IfcUnitEnum.PLANEANGLEUNIT);
HeightUnitIsLength : NOT EXISTS(SELF.HeightUnit) OR (SELF.HeightUnit.UnitType=IfcUnitEnum.LENGTHUNIT);
END_ENTITY;
EXPRESS-G diagram
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