Table 6.291 — 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 Representation> instances specifying a standardized mechanism by which to organize the members that compose the union.

The union_reason field specifies the reason why the given instance of <DRM Union Of Geometry> was created to organize its components.

The ordering_reason field specifies whether the ordering of the component <DRM Geometry Representation> instances of the given <DRM Union Of Geometry> instance is semantically significant, and if so, what that significance is.

Clarifications

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

2 An association between two <DRM Geometry Hierarchy> instances indicates that the environmental object(s) that they represent have the semantic relationship indicated by the <DRM Base Association Data> instance on the association relationship.

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

4 An association between two <DRM Geometry Hierarchy> instances indicates that the environmental object(s) that they represent have the semantic relationship indicated by the <DRM Base Association Data> instance on the association relationship.

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

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

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

Class diagram

Figure 6.349 — DRM_Union_Of_Geometry

Inherited field elements

Field name

Range

Field data type

unique_descendants

 

Boolean

strict_organizing_principle

 

Boolean

Field elements

Field name

Range

Field data type

union_reason

 

Union_Reason

ordering_reason

 

Ordering_Reason

Associated to (one-way) (inherited)

Associated to (one-way)
  • None.

Associated by (one-way) (inherited)

Associated by (one-way)
  • None.

Associated with (two-way) (inherited)
  • None.

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

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> instance. What the radar sees is modeled with a Radar Cross-section (RCS) <DRM Property Table> instance. The algorithm (or field measurements) that computed the RCS table used axes that do not match the SRF. Therefore, RCS axes of azimuth and elevation angle are misused unless some reference directions can be attached to the entire <DRM Union Of Geometry> instance.