Table 6.294 — DRM_Union_Of_Primitive_Geometry

Property

Description

Class
  • <DRM Union Of Primitive Geometry>

Superclass

Subclass
  • None.

Definition

An instance of this DRM class is a <DRM Union Of Geometry> instance that is composed solely of <DRM Primitive Geometry> instances.

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 6.352 — DRM_Union_Of_Primitive_Geometry

Inherited field elements

Field name

Range

Field data type

unique_descendants

 

Boolean

strict_organizing_principle

 

Boolean

union_reason

 

Union_Reason

ordering_reason

 

Ordering_Reason

Field elements

Field name

Range

Field data type

None

    

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)

Constraints

Example(s)
  • Consider a typical geometric representation of an airport runway, in which the runway surface is represented by a layer of polygons, overlaid by stripes (decal polygons).

    To ensure that the necessary rendering order is followed, the data provider creates a <DRM Union Of Primitive Geometry> instance U, and attaches each <DRM Polygon> instance as a component of U, in order of increasing relative rendering priority. Tthe <DRM Polygon> instance with the lowest relative rendering priority is attached first.

    After all the <DRM Polygon> instances in the underlying layer have been attached, the decal <DRM Polygon> instances are processed in the order in in which they will be rendered.

    If a specific method is used for the ordering, the data provider specifies it in U’s ordering_reason field. In this case, the data was created for a Z-buffered rendering system that supports layers, so ordering_reason is set to LAYERED_HIGH_QUALITY_RENDERING.

  • A collection of <DRM Polygon> instances making up the graphical representation of a forest canopy.

  • A 10 kilometre by 20 kilometre triangulated irregular network of <DRM Polygon> instances.