Table 6.287 — DRM_Union_Of_Geometry

Property

Description

Class
  • <DRM Union Of Geometry>

Superclass

Subclass

Definition

An instance of one of the concrete subclasses of this abstract DRM class is an aggregation of <DRM Geometry> specifying a standardized mechanism by which to organize the members that compose the union.

Class diagram

Figure 6.345 — DRM_Union_Of_Geometry

Inherited field elements

Field name

Range

Field data type

unique_descendants1

 

Boolean

strict_organizing_principle2

 

Boolean

Field elements

Field name

Range

Field data type

union_reason

 

Union_Reason

ordering_reason

 

Ordering_Reason

Associated to (one-way) (inherited)
  • None.

Associated to (one-way)
  • None.

Associated by (one-way) (inherited)

Associated by (one-way)
  • None.

Associated with (two-way) (inherited)

Associated with (two-way)
  • None.

Composed of (two-way) (inherited)

Composed of (two-way)

Composed of (two-way metadata) (inherited)

Composed of (two-way metadata)
  • None.

Component of (two-way) (inherited)

Component of (two-way)
  • None.

Constraints

Clarifications

1 If this value is TRUE, each “descendant” of this aggregation - that is, each <DRM Geometry> instance that exists in the component tree rooted at the given <DRM Aggregate Geometry> - shall be unique, in the sense that it shall appear in only one “branch” of this aggregation. If unique_descendants is FALSE, at least one <DRM Geometry> instance appears in more than one “branch” of the aggregation.

2 If this value is TRUE, each “branch” of this aggregation strictly complies with the organizing principle for its particular subclass. If this value is 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.

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

4 An association between two <DRM Geometry Hierarchy> instances indicates that they are alternate representations of the same environmental object.

5 An association from a <DRM Hierarchy Summary Item> instance to a <DRM Geometry Hierarchy> indicates that the <DRM Hierarchy Summary Item> summarizes that <DRM Geometry Hierarchy>.

6 An association from a <DRM Reference Surface> instance to a <DRM Geometry Hierarchy> indicates that the <DRM Geometry Hierarchy> organizes the geometric objects that specify the resolution surface of the <DRM Reference Surface>.

7 In the case where multiple <DRM Collision Volume> components are specified for a given <DRM Aggregate Geometry>, the union of the volumes thus specified is used in collision detection.

Example(s)

  • An antenna assembly is contained in a weather protection enclosure. Visually, only the opaque enclosure can be seen. But at microwave frequencies, the enclosure is invisible and only the antenna can be “seen”. The entire structure is contained in a <DRM Union Of Geometry>. What the Radar “sees” is modeled with a Radar Cross-section (RCS) <DRM Property Table>. The algorithm (or field measurements) that computed the RCS table used axes that do not match the spatial reference frame (world or model as the case may be). Therefore, RCS axes of azimuth and elevation angle are misused unless some REFERENCE DIRECTIONS can be attached to the entire <DRM Union Of Geometry>.