IfcMapConversion

Item	Change	Description
IFC2x3 to IFC4 4.0.0.0
IfcMapConversion	ADDED
IFC4x3_RC2 to IFC4x3_RC3
IfcMapConversion
ScaleY	MODIFIED	Instantiation changed to OPTIONAL.
ScaleZ	MODIFIED	Instantiation changed to OPTIONAL.

Semantic definitions at the entity

Entity definition

The map conversion deals with transforming the local engineering coordinate system, often called world coordinate system, into the coordinate reference system of the underlying map.

NOTE The IfcMapConversion does not handle the projection of a map from the geodetic coordinate reference system.

The map conversion allows to convert the local origin of the local engineering coordinate system to its place within a map (easting, northing, orthogonal height) and to rotate the x-axis of the local engineering coordinate system within the horizontal (easting/westing) plane of the map.

NOTE The z axis of the local engineering coordinate system is always parallel to the z axis of the map coordinate system.

The scale factor can be used when the length unit for the 3 axes of the map coordinate system are not identical with the length unit established for this project (see IfcProject.UnitsInContext), if omitted, the scale factor 1.0 is assumed.

HISTORY New entity in IFC4

Attribute definitions

#	Attribute	Type	Cardinality	Description	G
3	Eastings	IfcLengthMeasure		Specifies the location along the easting of the coordinate system of the target map coordinate reference system. NOTE for right-handed Cartesian coordinate systems this would establish the location along the x axis.	X
4	Northings	IfcLengthMeasure		Specifies the location along the northing of the coordinate system of the target map coordinate reference system. NOTE for right-handed Cartesian coordinate systems this would establish the location along the y axis	X
5	OrthogonalHeight	IfcLengthMeasure		Orthogonal height relativ to the vertical datum specified. NOTE for right-handed Cartesian coordinate systems this would establish the location along the z axis	X
6	XAxisAbscissa	IfcReal	?	Specifies the value along the easting axis of the end point of a vector indicating the position of the local x axis of the engineering coordinate reference system. NOTE 1 for right-handed Cartesian coordinate systems this would establish the location along the x axis NOTE 2 together with the XAxisOrdinate it provides the direction of the local x axis within the horizontal plane of the map coordinate system	X
7	XAxisOrdinate	IfcReal	?	Specifies the value along the northing axis of the end point of a vector indicating the position of the local x axis of the engineering coordinate reference system. NOTE 1 for right-handed Cartesian coordinate systems this would establish the location along the y axis XAxisAbscissa it provides the direction of the local x axis within the horizontal plane of the map coordinate system.	X
8	Scale	IfcReal	?	Scale to be used, when the units of the CRS are not identical to the units of the engineering coordinate system. If omited, the value of 1.0 is assumed.	X

Formal Propositions

Rule	Description
TargetCRSProjected	IfcCoordinateOperation.TargetCRS is of type IfcGeographicCRS.
ValidXAxis	Both XAxisAbscissa and XAxisOrdinate must not be zero.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	G
IfcCoordinateOperation
1	SourceCRS	IfcCoordinateReferenceSystemSelect		Source coordinate reference system for the operation.	X
2	TargetCRS	IfcCoordinateReferenceSystem		Target coordinate reference system for the operation.	X
IfcMapConversion
3	Eastings	IfcLengthMeasure		Specifies the location along the easting of the coordinate system of the target map coordinate reference system. NOTE for right-handed Cartesian coordinate systems this would establish the location along the x axis.	X
4	Northings	IfcLengthMeasure		Specifies the location along the northing of the coordinate system of the target map coordinate reference system. NOTE for right-handed Cartesian coordinate systems this would establish the location along the y axis	X
5	OrthogonalHeight	IfcLengthMeasure		Orthogonal height relativ to the vertical datum specified. NOTE for right-handed Cartesian coordinate systems this would establish the location along the z axis	X
6	XAxisAbscissa	IfcReal	?	Specifies the value along the easting axis of the end point of a vector indicating the position of the local x axis of the engineering coordinate reference system. NOTE 1 for right-handed Cartesian coordinate systems this would establish the location along the x axis NOTE 2 together with the XAxisOrdinate it provides the direction of the local x axis within the horizontal plane of the map coordinate system	X
7	XAxisOrdinate	IfcReal	?	Specifies the value along the northing axis of the end point of a vector indicating the position of the local x axis of the engineering coordinate reference system. NOTE 1 for right-handed Cartesian coordinate systems this would establish the location along the y axis XAxisAbscissa it provides the direction of the local x axis within the horizontal plane of the map coordinate system.	X
8	Scale	IfcReal	?	Scale to be used, when the units of the CRS are not identical to the units of the engineering coordinate system. If omited, the value of 1.0 is assumed.	X

Formal representations

XML Specification

 <xs:element name="IfcMapConversion" type="ifc:IfcMapConversion" substitutionGroup="ifc:IfcCoordinateOperation" nillable="true"/>

 <xs:complexType name="IfcMapConversion">

  <xs:complexContent>

   <xs:extension base="ifc:IfcCoordinateOperation">

    <xs:attribute name="Eastings" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="Northings" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="OrthogonalHeight" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="XAxisAbscissa" type="ifc:IfcReal" use="optional"/>

    <xs:attribute name="XAxisOrdinate" type="ifc:IfcReal" use="optional"/>

    <xs:attribute name="Scale" type="ifc:IfcReal" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcMapConversion

 SUPERTYPE OF(IfcMapConversionScaled)

 SUBTYPE OF (IfcCoordinateOperation);

  Eastings : IfcLengthMeasure;

  Northings : IfcLengthMeasure;

  OrthogonalHeight : IfcLengthMeasure;

  XAxisAbscissa : OPTIONAL IfcReal;

  XAxisOrdinate : OPTIONAL IfcReal;

  Scale : OPTIONAL IfcReal;

 WHERE

  TargetCRSProjected : 'IFCREPRESENTATIONRESOURCE.IfcProjectedCRS' IN TYPEOF(SELF\IfcCoordinateOperation.TargetCRS);
  ValidXAxis : (NOT EXISTS(XAxisAbscissa) AND NOT EXISTS(XAxisOrdinate)) OR

(NOT EXISTS(XAxisAbscissa) AND XAxisOrdinate <> 0.0) OR

(NOT EXISTS(XAxisOrdinate) AND XAxisAbscissa <> 0.0) OR

(EXISTS(XAxisAbscissa) AND EXISTS(XAxisOrdinate) AND NOT ((XAxisAbscissa = 0.0) AND (XAxisOrdinate = 0.0)));
END_ENTITY;

 EXPRESS-G diagram

	Konvertierung in kartographische Koordinaten
	Map Conversion