The SEDRIS Data Representation Model
APPENDIX A - Classes
Areal Feature

Class Name: Areal Feature

Superclass - <Primitive Feature>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

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

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

Example

  1. Consider an <Areal Feature> instance representing a lake. It has a <Feature Face> instance, which defines its size, shape, and topological relationships; a <Classification Data> component that identifies it as a lake; <Property Value> components that describe its characteristics, such as bottom composition; and a <Label> component 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 the DRM. <Areal Feature> instances may exist at any level of topology.

Can the topology of an <Areal Feature> instance 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> instance 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 is represented as a single <Areal Feature> instance, but might require multiple <Feature Face> instances.

Constraints

Associated to (one-way) (inherited)

Associated by (one-way) (inherited)

Associated with (two-way)

Composed of (two-way) (inherited)

Composed of (two-way metadata) (inherited)

Component of (two-way) (inherited)

Inherited Field Elements

This class has no inherited field elements.

Notes

Associated to Notes


Feature_Representation

An association between two <Feature Representation> instances indicates that the environmental object(s) that they represent have the semantic relationship indicated by the <Base Association Data> link object on the association relationship.


Geometry_Hierarchy

An association between a <Geometry Hierarchy> instance and a <Feature Representation> instance indicates that the environmental object(s) that they represent have the semantic relationship indicated by the <Base Association Data> link object on the association relationship.


Property_Grid

An association between a <Property Grid> instance and a <Feature Representation> instance indicates that the environmental object(s) represented by the <Feature Representation> instance and the <Property Grid> instance (or some specific cell data within that <Property Grid> instance) have the semantic relationship indicated by the <Base Association Data> link object on the association relationship. Each associated <Property Grid> instance indicates whether the entire <Property Grid> instance or only some specific cell data within it is participating in the relationship in question.

Associated from Notes


Feature_Representation

An association between two <Feature Representation> instances indicates that the environmental object(s) that they represent have the semantic relationship indicated by the <Base Association Data> link object on the association relationship.


Geometry_Hierarchy

An association between a <Geometry Hierarchy> instance and a <Feature Representation> instance indicates that the environmental object(s) that they represent have the semantic relationship indicated by the <Base Association Data> link object on the association relationship.


Property_Grid

An association between a <Property Grid> instance and a <Feature Representation> instance indicates that the environmental object(s) represented by the <Feature Representation> instance and the <Property Grid> instance (or some specific cell data within that <Property Grid> instance) have the semantic relationship indicated by the <Base Association Data> link object on the association relationship. Each associated <Property Grid> instance indicates whether the entire <Property Grid> instance or only some specific cell data within it is participating in the relationship in question.

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> instance by the consumer. These <Image Mapping Function> components shall use <Image Anchor> components to specify the mapping.


Presentation_Domain

The <Presentation Domain> component is needed because, in many cases, a <Primitive Feature> instance may be significant only for a particular domain, such as radar.


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Last updated: July 26, 2006 Copyright © 2006 SEDRIS