The planar surface is an unbounded surface in the direction of x and y. Bounded planar surfaces are defined by using a subtype of IfcBoundedSurface with BasisSurface being a plane.

NOTE  Definition according to ISO/CD 10303-42:1992
A plane is an unbounded surface with a constant normal. A plane is defined by a point on the plane and the normal direction to the plane. The data is to be interpreted as follows:

   C = Position.Location
   x = Position.P[1]
   y = Position.P[2]
   z = Position.P[3] => normal to plane

and the surface is parameterized as:

where the parametric range is -∞ < u,v < ∞. In the above parameterization the length unit for the unit vectors x and y is derived from the context of the plane.

NOTE  A rectangular bounded planar surface can be defined by an IfcRectangularTrimmedSurface with BasisSurface being the plane and U1 = left bound in x, U2 = right bound in x, V1 = lower bound in y, V2 = upper bound in y if viewed into the direction of the negative normal. (assuming the Usense and Vsense agree to the sense of the basis surface).

The inherited attributes are interpreted as

• SELF\IfcElementarySurface.Position defines the location and orientation of the planar surface.
• SELF\IfcElementarySurface.Position.Location defines a point on the planar surface.
• SELF\IfcElementarySurface.Position.P[3] defines the normal of the planar surface.

NOTE  Entity adapted from plane in ISO 10303-42.

HISTORY  New entity in IFC1.5