Class Name: Areal Feature

Superclass - <Primitive Feature>

Subclasses

Definition

An instance of this DRM class is a <Primitive Feature> that encloses a bounded region, such as a forest or a built-up area.

Primary Page in DRM Diagram:

• 8

Secondary Pages in DRM Diagram:

Example

1. Consider an <Areal Feature> representing a lake. It has a <Feature Face>, which defines its size, shape, and topological relationships; <Property Value> components that describe its characteristics, such as bottom composition, and a <Label> that identifies it as "Duck Lake".

FAQs

Is Level 3 feature topology required in order for <Areal Feature> instances to exist?

No. Although in VPF, for example, the mere presence of Faces implies Level 3 topology, this is not the case in SEDRIS. <Areal Feature> instances may exist at any level of topology.

Can an <Areal Feature>'s topology consist of multiple <Feature Face> instances? If so, are these <Feature Face> instances required to be adjacent or connected to one another?

An <Areal Feature> can consist of multiple <Feature Face> instances. There is no requirement that the <Feature Face> instances be connected to one another.

For example, a forest that has a stream and a road passing through it commonly would be represented as a single <Areal Feature>, but might require multiple <Feature Face> instances.

Constraints

• <<No Attribute Conflicts>>
• <<Non Crossing Aggregations>>
• <<Non Crossing Associations>>
• <<Precedence of Attribute Set Index>>
• <<Colour Mapping Restrictions>>
• <<Image Mapping Functions and Texture Coordinates>>

Associated with (two-way)(inherited)

• zero or more <Feature> instances (notes)
• zero or more <Geometry Hierarchy> instances (notes)
• zero or more <Property Grid> instances (notes)

Associated with (two-way)

• one or more <Feature Face> instances through <Face Directions>

Composed of (two-way)(inherited)

• zero or more {ordered} <Attribute Set Index> instances
• zero or one <Classification Data> instance
• zero or more <Label> instances
• zero or more <Property Table> instances
• zero or more <Property Table Reference> instances
• zero or more <Property Value> instances
• zero or one <Rendering Priority Level> instance
• zero or more <Colour> instances
• zero or more {ordered} <Image Mapping Function> instances (notes)
• zero or one <Presentation Domain> instance (notes)
• zero or one <Spatial Domain> instance

Composed of (two-way metadata)(inherited)

• zero or one <Access> instance
• zero or more <Browse Media> instances
• zero or more <Cross Reference> instances
• zero or one <Data Quality> instance
• zero or one <Keywords> instance
• zero or one <Point Of Contact> instance
• zero or one <Time Constraints Data> instance

Component of (two-way)(inherited)

• zero or more <Union Of Features> instances

Inherited Field Elements

Notes

Associated with Notes

Feature

 An association between two <Feature> instances indicates
 that they are alternate representations of the same
 environmental object.

Geometry_Hierarchy

 An association between a <Geometry Hierarchy> instance and a
 <Feature> instance indicates that the <Geometry Hierarchy>
 and the <Feature> are alternate representations of the same
 environmental object.

Property_Grid

 An association between a <Property Grid> instance and a
 <Feature> instance indicates that the <Feature> and the <Property Grid>
 (or some specific cell data within that <Property Grid>) are
 alternate representations of the same environmental object.
 Each associated <Property Grid> will indicate which is the case.

Composed of Notes

Image_Mapping_Function

 These components support "attributes for derived objects"; that
 is, they are used only to specify texture mapping information
 for geometry that is derived from the <Primitive Feature> by
 the consumer. These <Image Mapping Function> components shall use
 <Image Anchor> components to specify the mapping.

Presentation_Domain

 This is needed because in many cases, a <Primitive Feature> may be
 significant only for a particular domain, such as radar.