8.18.3.3 IfcGeographicCRS
8.18.3.3.1 Semantic definition
A IfcGeographicCRS is a non-Cartesian CRS that uses a three-dimensional ellipsoid surface to reference locations on the Earth as a latitude, longitude pair and the elevation above or below the ellipsoid.
8.18.3.3.2 Entity inheritance
8.18.3.3.3 Attributes
| # | Attribute | Type | Description |
|---|---|---|---|
| IfcCoordinateReferenceSystem (4) | |||
| 1 | Name | OPTIONAL IfcLabel |
Name by which the coordinate reference system is identified. |
| 2 | Description | OPTIONAL IfcText |
Informal description of this coordinate reference system Example for ellipsoid:
ELLIPSOID[ |
| HasCoordinateOperation | SET [0:1] OF IfcCoordinateOperation FOR SourceCRS |
Indicates conversion between coordinate systems. In particular it refers to an IfcCoordinateOperation between this coordinate reference system, and another Geographic 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 4 hidden inherited attributes Click to hide 4 inherited attributes | |||
| IfcGeographicCRS (3) | |||
| 3 | GeodeticDatum | OPTIONAL IfcIdentifier |
Name by which this datum is identified. |
| 4 | PrimeMeridian | OPTIONAL IfcIdentifier |
The identification of the meridian defining zero longitude in the used geographic CRS. |
| 5 | Unit | OPTIONAL IfcNamedUnit |
Unit of the coordinate tuple composing the coordinate system. |
8.18.3.3.4 Formal propositions
| Name | Description |
|---|---|
| IsPlaneAngleUnit |
The map unit shall be given, if present, as a plane angle unit. |
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8.18.3.3.5 Formal representation
ENTITY IfcGeographicCRS
SUBTYPE OF (IfcCoordinateReferenceSystem);
GeodeticDatum : OPTIONAL IfcIdentifier;
PrimeMeridian : OPTIONAL IfcIdentifier;
Unit : OPTIONAL IfcNamedUnit;
WHERE
IsPlaneAngleUnit : NOT(EXISTS(Unit)) OR (Unit.UnitType=IfcUnitEnum.PLANEANGLEUNIT);
END_ENTITY;