8.9.3.65 IfcSphericalSurface
8.9.3.65.1 Semantic definition
The IfcSphericalSurface is a bounded elementary surface. The inherited Position attribute defines the IfcAxis2Placement3D 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 positive direction towards the north pole, and by its negative directions towards the south pole.
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 cos v ((cos u) x + (sin u) y) + R(sin v) z where the parametrisation range is 0 ≤ u ≤ 360 degrees and -90 ≤ v ≤ 90 degrees. u and v are 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) = cos v((cos u)x + (sin u)y) + (sin v)z,
8.9.3.65.2 Entity inheritance
-
- IfcSurface
- IfcAnnotationFillArea
- IfcBooleanResult
- IfcBoundingBox
- IfcCartesianPointList
- IfcCartesianTransformationOperator
- IfcCsgPrimitive3D
- IfcCurve
- IfcDirection
- IfcFaceBasedSurfaceModel
- IfcFillAreaStyleHatching
- IfcFillAreaStyleTiles
- IfcGeometricSet
- IfcHalfSpaceSolid
- IfcLightSource
- IfcPlacement
- IfcPlanarExtent
- IfcPoint
- IfcSectionedSpine
- IfcSegment
- IfcShellBasedSurfaceModel
- IfcSolidModel
- IfcTessellatedItem
- IfcTextLiteral
- IfcVector
8.9.3.65.3 Attributes
| # | Attribute | Type | Description |
|---|---|---|---|
| IfcRepresentationItem (2) | |||
| 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. |
|
| 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. |
|
| IfcSurface (1) | |||
| * | Dim | IfcDimensionCount |
This attribute is formally derived. The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item. |
| IfcElementarySurface (1) | |||
| 1 | Position | IfcAxis2Placement3D |
The position and orientation of the surface. This attribute is used in the definition of the parameterization of the surface. |
| Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes | |||
| IfcSphericalSurface (1) | |||
| 2 | Radius | IfcPositiveLengthMeasure |
The radius of the sphere. |
8.9.3.65.4 Formal representation
ENTITY IfcSphericalSurface
SUBTYPE OF (IfcElementarySurface);
Radius : IfcPositiveLengthMeasure;
END_ENTITY;