IfcConnectionPointEccentricity is used to describe the geometric constraints that facilitate the physical connection of two objects at a point or vertex point with associated point coordinates. There is a physical distance, or eccentricity, etween the connection points of both object. The eccentricity can be either given by:

• providing the PointOnRelatingElement and the PointOnRelatedElement, where both point coordinates are not identical within a common parent coordinate system (latestly within the world coordinate system),
• providing the PointOnRelatingElement and the three distance measures, EccentricityInX, EccentricityInY, and EccentricityInZ (or only EccentricityInX, and EccentricityInY if the underlying coordinate system is two-dimensional), or
• providing both.

NOTE  If both, PointOnRelatedElement, and EccentricityInX, EccentricityInY, (EccentricityInZ) are provided, the values should be consistent. In case of any non-consistency, the calculated distance between PointOnRelatingElement and PointOnRelatedElement takes precedence.

The IfcPoint (or the IfcVertexPoint with an associated IfcPoint) at the PointOnRelatingElement attribute defines the point where the basic geometry items of the connected elements connects. The point coordinates are provided within the local coordinate system of the RelatingElement, as specified at the IfcRelConnects subtype that utilizes the IfcConnectionPointGeometry. Optionally, the same point coordinates can also be provided within the local coordinate system of the RelatedElement by using the PointOnRelatedElement attribute, otherwise the distance to the point at the RelatedElement has to be given by the three eccentricity values.

The explicit values for EccentricityInX, EccentricityInY, and EccentricityInZ are always measured in the following direction and coordinate system (defining when the value is positive or negative):

• from the PointOnRelatedElement to PointOnRelatingElement within the coordinate system of the RelatingElement.
• in addition: when used to specify connections in structural analysis models, the IfcStructuralMember is to be used as the RelatingElement of the relationship object utilizing IfcConnectionPointEccentricity, and the IfcStructuralConnection is the RelatedElement.

HISTORY  New entity in IFC2x3.