IfcEllipse

Natural language names
deEllipse
enEllipse
frEllipse
Semantic definitions at the entity
Entity definition

An IfcEllipse is a curve consisting of a set of points whose distances to two fixed points add to the same constant.

The inherited SELF\IfcConic.Position.Location is the center of the IfcEllipse, and the inherited SELF\IfcConic.Position.Position.P[1] is the direction of the SemiAxis1.

ellipse

Definition of the IfcEllipse within the a three-dimensional position coordinate system is shown in Figure 342.

It is placed within the object coordinate system of an element of which it is a representation.

Figure 342 — Ellipse placement and parameterization

 
NOTE  An elliptical arc segment is defined by using the IfcTrimmedCurve with BasisCurve

NOTE Definition according to ISO/CD 10303-42:1992
An ellipse is a conic section defined by the lengths of the semi-major and semi-minor diameters and the position (center or mid point of the line joining the foci) and orientation of the curve. Interpretation of the data shall be as follows:

C = position.location
x = position.p[1]
y = position.p[2]
z = position.p[3]
R1 = semi axis 1
R2 = semi axis 2

and the ellipse is parameterized as:

formula

The parameterization range is 0 ≤ u <≤ 2π (0 ≤ u ≤ 360 degree). In the placement coordinate system defined above, the ellipse is the equation C = 0, where

formula

The positive sense of the ellipse at any point is in the tangent direction, T, to the curve at the point, where

formula

NOTE  Entity adapted from ellipse defined in ISO 10303-42
HISTORY  New entity in IFC1.0
Attribute definitions
#AttributeTypeCardinalityDescription C
2SemiAxis1IfcPositiveLengthMeasure[1:1] The first radius of the ellipse which shall be positive. Placement.Axes[1] gives the direction of the SemiAxis1.X
3SemiAxis2IfcPositiveLengthMeasure[1:1] The second radius of the ellipse which shall be positive.X
Inherited definitions from supertypes
Entity inheritance IfcConic IfcCurve IfcGeometricRepresentationItem IfcRepresentationItem
Attribute inheritance
#AttributeTypeCardinalityDescriptionC
IfcRepresentationItem
LayerAssignmentIfcPresentationLayerAssignment
@AssignedItems
S[0:1]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. X
StyledByItemIfcStyledItem
@Item
S[0:1]Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve. X
IfcGeometricRepresentationItem
IfcCurve
Dim
:=IfcCurveDim(SELF)
IfcDimensionCount[1:1]The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. X
IfcConic
1PositionIfcAxis2Placement[1:1] The location and orientation of the conic. Further details of the interpretation of this attribute are given for the individual subtypes." X
IfcEllipse
2SemiAxis1IfcPositiveLengthMeasure[1:1] The first radius of the ellipse which shall be positive. Placement.Axes[1] gives the direction of the SemiAxis1.X
3SemiAxis2IfcPositiveLengthMeasure[1:1] The second radius of the ellipse which shall be positive.X
Formal representations
XSD Specification
 <xs:element name="IfcEllipse" type="ifc:IfcEllipse" substitutionGroup="ifc:IfcConic" nillable="true"/>
 <xs:complexType name="IfcEllipse">
  <xs:complexContent>
   <xs:extension base="ifc:IfcConic">
    <xs:attribute name="SemiAxis1" type="ifc:IfcPositiveLengthMeasure" use="optional"/>
    <xs:attribute name="SemiAxis2" type="ifc:IfcPositiveLengthMeasure" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcEllipse
 SUBTYPE OF (IfcConic);
  SemiAxis1 : IfcPositiveLengthMeasure;
  SemiAxis2 : IfcPositiveLengthMeasure;
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

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