Class Name: Ellipse

Superclass - <Surface Geometry>

Subclasses

Definition

An instance of this DRM class specifies a closed plane curve such that for each point on the curve, the sum of the point's distances from 2 fixed points (called the foci of the <Ellipse>) is a constant.

The major axis of the <Ellipse> is the line passing through the foci of the <Ellipse>. The minor axis of the <Ellipse> is the line perpendicular to the major axis that passes through the centre of the <Ellipse>. The component <Location 3D> locates the centre.

The first component <Reference Vector> (vector_type = SE_REF_VEC_TYP_MAJOR_AXIS) gives the direction of the major axis. The second component <Reference Vector> (vector_type = SE_REF_VEC_TYP_FACE_NORMAL) defines the normal direction to the plane of the <Ellipse>, and shall be perpendicular to the major axis <Reference Vector>.

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 <Elliptic Cylinder> 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

• <<No Attribute Conflicts>>
• <<Non Crossing Aggregations>>
• <<Non Cyclic Aggregations>>
• <<Precedence of Attribute 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 more {ordered} <Attribute Set Index> instances
• zero or one <Classification Data> instance
• 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 {ordered} <Reference Vector> instances (notes)

Composed of (two-way metadata)(inherited)

• zero or one <Time Constraints Data> instance

Component of (two-way)(inherited)

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

Location

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

Reference_Vector

 These are the elliptic cross section axes.

 The first component <Reference Vector> specifies the major
 axis direction with vector_type = SE_REF_VEC_TYP_MAJOR_AXIS.

 The second component <Reference Vector> specifies the major
 axis direction with vector_type = SE_REF_VEC_TYP_MINOR_AXIS.

Fields Notes

major_axis_length

 This is in metres > 0.0.

minor_axis_length

 This is in metres > 0.0.