The SEDRIS Data Representation Model
APPENDIX A - Classes
Aggregate Feature

Abstract Class Name: Aggregate Feature

Superclass - <Feature Hierarchy>

Subclasses

Definition

An instance of this DRM class specifies a collection of <Primitive Feature> instances and/or <Feature Hierarchy> instances organized according to some organizing principle specific to the particular subclass of <Aggregate Feature> being considered.

For most subclasses of <Aggregate Feature>, each individual branch of the aggregation is explicitly identified through a distinct link object. The various subclasses provide different mechanisms for organizing <Feature Representation> instances, which include:

alternate hierarchy:

Each branch is a <Feature Hierarchy> instance through a different <Hierarchy Data> link object, representing a different way of organizing the same underlying collection of <Feature Representation> instances.

classification:

Each branch is a <Feature Hierarchy> instance through a different <Classification Data> link object, representing a different thematic layer, or a different classification of <Feature Representation> instances (e.g., roads, railroads) within a single thematic layer.

level of detail:

Each branch is a <Feature Hierarchy> instance through a distinct (but possibly overlapping), <Base LOD Data> link object, representing an alternative that is to be used at a specified level of detail.

octant:

The <Aggregate Feature> instance represents an octant-related organization, where each branch is a <Feature Hierarchy> instance representing an octant, as identified through its <Octant Data> link object.

perimeter:

Each branch is a <Feature Hierarchy> instance that is located within a different cell of an irregular spatial index, as defined through its <Perimeter Data> link object.

quadrant:

The <Aggregate Feature> instance represents a quadrant related organization, in which each branch is a <Feature Hierarchy> instance representing a quadrant, as identified through its <Quadrant Data> link object.

spatial index:

The <Aggregate Feature> instance represents a regularly spaced spatial index grid, in which each branch is a <Feature Hierarchy> instance representing a different cell within the spatial index.

state:

The <Aggregate Feature> instance represents the different states of an environmental object for a specified EAC. Each branch represents the environmental object for a different state value of the specified EAC. Each branch is a <Feature Hierarchy> instance through a <State Data> link object that corresponds to the specified state value.

time:

The <Aggregate Feature> instance represents an environmental object that has different representations for different time periods. Each branch is a <Feature Hierarchy> instance through a distinct (though possibly overlapping) <Time Constraints Data> link object representing an alternative that shall be used for the time period specified through its <Time Constraints Data> link object.

union:

Each branch is a <Feature Representation> instance. The reason for organizing them into separate components is specified by the union_reason field.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

Example

See concrete subclasses for examples.

FAQs

What is the purpose of this class?

This class, through its subclasses, allows instances of <Feature Representation> to be hierarchically organized in a variety of different ways. The <Classification Related Features> subclass allows features to be organized according to their ECCs. The <Spatial Index Related Features>, <Perimeter Related Features>, <Quadrant Related Features>, and <Octant Related Features> subclasses allow features to be organized according to their locations. The <Alternate Hierarchy Related Features>, <LOD Related Features>, <State Related Features>, and <Time Related Features> subclasses allow multiple alternative representations of collections of <Feature Representation> instances to be created, with different alternatives used under different conditions. Finally, the <Union Of Features> subclass allows features to be grouped arbitrarily.

Constraints

Associated to (one-way) (inherited)

Associated by (one-way) (inherited)

Composed of (two-way) (inherited)

Composed of (two-way)

Composed of (two-way metadata) (inherited)

Component of (two-way) (inherited)

Inherited Field Elements

This class has no inherited field elements.

Field Elements

SE_Boolean unique_descendants; 9
SE_Boolean strict_organizing_principle; 10

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

The <Image Mapping Function> components support texture mapping information for geometry that is to be derived from the <Aggregate Feature> instance by the consumer. These <Image Mapping Function> instances shall use <Image Anchor> components to specify the mapping.


Presentation_Domain

A <Presentation Domain> component is needed for <Aggregate Feature> instances that are significant only for a particular domain, such as radar.

Fields Notes

unique_descendants

If the value of the unique_descendants field is SE_TRUE, each descendant shall be unique in the sense that it shall appear in only one branch of this aggregation. Each descendant is a <Feature Representation> instance within the component tree rooted at the <Aggregate Feature> instance. If unique_descendants is SE_FALSE, at least one <Feature Representation> instance appears in more than one branch of the aggregation.

strict_organizing_principle

If the value of the strict_organizing_principle field is SE_TRUE, each branch of this aggregation strictly complies with the organizing principle for its particular subclass. If this value is SE_FALSE, at least one branch does not strictly comply with the given organizing principle. See the organizing principle constraint for each specific subclass for details.


Prev: Absolute Time Interval. Next: Aggregate Geometry. Up:Index.

Last updated: July 26, 2006 Copyright © 2006 SEDRIS