Class Name: Ellipse

Superclass - <Surface Geometry>

Subclasses

Definition

An instance E of this DRM class specifies a closed plane curve such that for each point P on the curve, the sum of P's distances from two fixed points (called the foci of E) is a constant. The <Location> component of E specifies the centre of the instance E.

The line passing through the foci of E is termed the major axis of E. The direction of the major axis of E is specified by the component <Reference Vector> of E with vector_type = MAJOR_AXIS.

The line passing through the centre of E and perpendicular to the major axis of E is termed the minor axis of E. The direction of the minor axis of E is specified by the component <Reference Vector> of E with vector_type = MINOR_AXIS.

Primary Page in DRM Diagram:

• 5

Secondary Pages in DRM Diagram:

• 13

Example

1. The physical extent of certain underwater acoustic phenomena are best described by oval surface geometries in some cases, and by <Volume Object> instances in others.

FAQs

Why doesn't SEDRIS have a Circle class?

Because a circle is a special case of an ellipse for which the major and minor axes have the same length.

Constraints

• <<Publishable Object>>
• <<No Attribute Conflicts>>
• <<Non Crossing Aggregations>>
• <<Non Cyclic Aggregations>>
• <<Precedence of Property Set Index>>
• <<Colour Mapping Restrictions>>
• <<Continuous LOD Restrictions>>
• <<Image Mapping Functions and Texture Coordinates>>
• <<Nested Primitive Geometry>>

Associated with (two-way)

• zero or one <Geometry Node> instance (notes)

Composed of (two-way) (inherited)

• zero or one <Classification Data> instance
• zero or more {ordered} <Property Set Index> instances
• zero or more <Property Table> instances
• zero or more <Property Table Reference> instances
• zero or more <Property Value> instances
• zero or more <Colour> instances
• zero or more {ordered} <Image Mapping Function> instances
• zero or one <Light Rendering Properties> instance
• zero or one <Presentation Domain> instance
• zero or one <Rendering Priority Level> instance
• zero or one <Rendering Properties> instance
• zero or more <Tack Point> instances
• zero or one <Union Of Primitive Geometry> instance (notes)

Composed of (two-way)

• one <Location> instance (notes)
• exactly 2 <Reference Vector> instances (notes)

Composed of (two-way metadata) (inherited)

• zero or one <Time Constraints Data> instance

Component of (two-way) (inherited)

• zero or more <Union Of Primitive Geometry> instances

Inherited Field Elements

Field Elements

Notes

Associated with Notes

Geometry_Node

 This corresponds to the centre of the given <Ellipse> instance.

Composed of Notes

Union_Of_Primitive_Geometry

 A <Primitive Geometry> instance contains a
 <Union Of Primitive Geometry> instance as a component only
 when that <Primitive Geometry> instance can be decomposed
 into nested <Primitive Geometry> instances, as (for
 example) a <Polygon> instance can be decomposed into
 subfaces.

Location

 This is the location of the centre of the given <Ellipse> instance.

Reference_Vector

 For a given instance E of <Ellipse>, one <Reference Vector>
 component shall have vector_type = MAJOR_AXIS, the other
 shall have vector_type = MINOR_AXIS, and the two
 shall be mutually perpendicular.

Fields Notes

major_axis_length

 The major_axis_length field is specified in metres.

minor_axis_length

 The minor_axis_length field is specified in metres.