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 <Reference Vector> component of E with vector_type = SE_REFVEC_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 <Reference Vector> component of E with vector_type = SE_REFVEC_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 <Ellipse> instances in some cases, and by <Volume Object> instances in others.

FAQs

Why doesn't the DRM 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>>
• <<Constraints On Components>>
• <<Non Cyclic Aggregations>>
• <<Precedence of Property Set Index>>
• <<Property Constraints>>
• <<Colour Mapping Constraints>>
• <<Continuous LOD Constraints>>
• <<Image Mapping Functions and Texture Coordinates>>
• <<Nested Primitive Geometry>>
• <<Presentation Domain Constraints>>

Associated with (two-way)

• zero or one <Geometry Node> instance¹

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> instance²

Composed of (two-way)

• one <Location> instance³
• exactly 2 <Reference Vector> instances⁴

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

Composed of Notes

Union_Of_Primitive_Geometry

EXAMPLE  A <Polygon> instance can be decomposed into multiple <Polygon> instances representing subfaces.

Location

Reference_Vector

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.