Class Name: Feature Edge

Superclass - <Feature Topology>

Subclasses

Definition

A one-dimensional <Feature Topology> instance consisting of an ordered collection of <Locations> connecting one <Feature Node> to another <Feature Node>. The orientation of a <Feature Edge> is defined by the order of its <Location> components, taken in conjunction with its starting <Feature Node> and ending <Feature Node>.

A <Feature Edge> is used to represent the location of a segment of either

1. one or more <Linear Features>,
2. a boundary of one or more <Feature Faces>, or
3. both.

Primary Page in DRM Diagram:

• 12

Secondary Pages in DRM Diagram:

• 8

Example

1. A <Linear Feature> representing the centreline of a road would be defined by one or more <Feature Edge> instances. The border of a forested area would be defined by a collection of one or more <Feature Edge> instances.

FAQs

When are <Feature Edge> instances required?

<Feature Edges> are required whenever either <Linear Features> or <Feature Faces> are present.

Does the sequence of <Locations> that make up a <Feature Edge> include the endpoints?

No. The endpoints of a <Feature Edge> are defined by its ordered <Feature Node> associates.

Are there any geometric constraints on the sequence of <Locations> that make up a <Feature Edge>?

Yes. In general, there should be no duplicate <Locations> (i.e., having the same coordinates) within a <Feature Edge>. The path defined by the sequence of line segments that connect the consecutive <Locations> that make up a <Feature Edge> shall not intersect or overlap itself. <Feature Edges> may meet only at <Feature Nodes>.

How are <Feature Edges> affected by the feature topology level?

At feature topology level 2 or higher, no <Feature Edge> may intersect with or overlap another <Feature Edge>. At feature topology level 3, each <Feature Edge> forms part of the boundaries of exactly two <Feature Faces>.

Constraints

• <<No Attribute Conflicts>>
• <<Connected Edge Restrictions>>
• <<Edges Bordering Faces>>
• <<Feature Edge Restrictions>>
• <<Non Crossing Associations>>

Associated to (one-way)

• zero or more {ordered} <Feature Face> instances (notes)
• exactly 2 {ordered} <Feature Node> instances (notes)

Associated by (one-way)

• zero or more <Connected Feature Edge> instances through <Edge Directions>
• zero or more <Feature Face Ring> instances through <Edge Directions> (notes)

Associated with (two-way)

• zero or more <Feature Edge> instances
• zero or more <Linear Feature> instances through <Edge Directions>

Composed of (two-way)(inherited)

• zero or one <Feature ID> instance
• zero or more <Property Value> instances

Composed of (two-way)

• zero or more {ordered} <Location> instances
• zero or more <Same As Feature Edge> instances

Component of (two-way)(inherited)

• zero or more <Union Of Feature Topology> instances

Inherited Field Elements

Notes

Associated with Notes

Feature_Face

 The <Feature Faces> (if any) that are bordered by
 this <Feature Edge>, ordered counterclockwise when
 looking along the <Feature Edge>.

 The converse of this relationship is that between
 <Feature Face Ring> and <Feature Edge>.

Feature_Face_Ring

 This association specifies that the <Feature Face Ring>
 is "bounded by" this <Feature Edge>.

Feature_Node

 This association specifies that the <Feature Edge>
 is "bounded by" the <Feature Nodes>.

 The first <Feature Node> is the starting node of
 the <Feature Edge>, while the second <Feature Node>
 is the ending node.