added |

The *IfcSphericalSurface* is a bounded elementary surface. The inherited *Position* attribute defines the *IfcAxisPlacement3D* and provides:

*SELF\IfcElementarySurface.Position*: The location and orientation of the axis system for the primitive.*SELF\IfcElementarySurface.Position.Location*: The center of the spherical surface.*SELF\IfcElementarySurface.Position.Position[3]:*The z axis points at its positve direction towards the north pole, and by its negative directions towards the south pole.

NOTE Definition according to ISO/CD 10303-42:1992

AnIfcSphericalSurfaceis a type of an elementary surface, which is at a constant distance (theradius) from a central point. A spherical surface is defined by the radius and the location and orientation of the surface.The data is to be interpreted as follows:

C = Position.Location

x = Position.P[1]

y = Position.P[2]

z = Position.P[3] (axis of spherical surface)

R= Radius and the surface is parametrised as

=σ(u,v)C+ R cosv((cosu)x+ (sinu)y) + R(sinv)zwhere the parametrisation range is0 ≤ u ≤ 360degrees and-90 ≤ v ≤ 90degrees.uandvare angular parameters and when numerical values are specified they shall use the current units for plane angle measure.In the placement coordinate system defined above, the surface is represented by the equation

S= 0, where

S(x, y, z) = x^2^ + y^2^ + z^2^ - R^2^.The positive direction of the normal to the surface at any point on the surface is given by

(S~x~, S~y~, S~z~ ).The unit normal is given by

N(u,v)= cosv((cosu)x+ (sinu)y) + (sinv)z,NOTE Entity adapted from

spherical_surfacedefined in ISO 10303-42.HISTORY New entity in IFC4 Addendum 2.

# | Attribute | Type | Description |
---|---|---|---|

IfcRepresentationItem | |||

LayerAssignment | SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems | Assignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items. > IFC2x3 CHANGE The inverse attribute LayerAssignments has been added. > IFC4 CHANGE The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed. | |

StyledByItem | SET [0:1] OF IfcStyledItem FOR Item | Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve. > IFC2x3 CHANGE The inverse attribute StyledByItem has been added. | |

IfcGeometricRepresentationItem | |||

IfcSurface | |||

Dim | INVALID | The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item. > IFC4 CHANGE Derived attribute promoted from subtypes. | |

IfcElementarySurface | |||

1 | Position | IfcAxis2Placement3D | The position and orientation of the surface. This attribute is used in the definition of the parameterization of the surface. |

IfcSphericalSurface | |||

2 | Radius | IfcPositiveLengthMeasure | The radius of the sphere. |

ENTITY IfcSphericalSurface SUBTYPE OF (IfcElementarySurface); Radius : IfcPositiveLengthMeasure; END_ENTITY;