8.18.3.5 IfcMapConversion

8.18.3.5.1 Semantic 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.

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.

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聽IfcProject.UnitsInContext), if omitted, the scale factor 1.0 is assumed.

8.18.3.5.2 Entity inheritance

8.18.3.5.3 Attributes

#	Attribute	Type	Description
IfcCoordinateOperation (2)
1	SourceCRS	IfcCoordinateReferenceSystemSelect	Source coordinate reference system for the operation.
2	TargetCRS	IfcCoordinateReferenceSystem	Target coordinate reference system for the operation.
Click to show 2 hidden inherited attributes Click to hide 2 inherited attributes
IfcMapConversion (8)
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.
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
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
6	XAxisAbscissa	OPTIONAL IfcReal	Specifies the value along the easing 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
7	XAxisOrdinate	OPTIONAL 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.
8	Scale	OPTIONAL IfcReal	Scale to be used, when the units of the CRS are not identical to the units of the engineering coordinate system. If omitted, the value of 1.0 is assumed.
9	ScaleY	OPTIONAL IfcReal	Scale Y by which the length measures in local engineering CS have to be multiplied to get map coordinates
10	ScaleZ	OPTIONAL IfcReal	Scale Z by which the length measures in local engineering CS have to be multiplied to get map coordinates

Table 8.18.3.5.K

8.18.3.5.4 Examples

Figure 8.18.3.5.A

Georeferencing_Tin_1
Figure 8.18.3.5.B

Tin_4
Figure 8.18.3.5.C

Tin_3
Figure 8.18.3.5.D

Georeferencing_Tin_2
Figure 8.18.3.5.E

Georeferencing_Tiny_Survey_1
Figure 8.18.3.5.F

Georeferencing_Tin_5
Figure 8.18.3.5.G

UT_SpatialStructure_4
Figure 8.18.3.5.H

Georeferencing_Tin_3
Figure 8.18.3.5.I

Georeferencing-1
Figure 8.18.3.5.J

Georeferencing_Tin_4

8.18.3.5.5 Formal representation

ENTITY IfcMapConversion
 SUBTYPE OF (IfcCoordinateOperation);
	Eastings : IfcLengthMeasure;
	Northings : IfcLengthMeasure;
	OrthogonalHeight : IfcLengthMeasure;
	XAxisAbscissa : OPTIONAL IfcReal;
	XAxisOrdinate : OPTIONAL IfcReal;
	Scale : OPTIONAL IfcReal;
	ScaleY : OPTIONAL IfcReal;
	ScaleZ : OPTIONAL IfcReal;
END_ENTITY;

8.18.3.5.6 References

IfcCoordinateOperation