Class Name: Oct Tree Related Geometry

Superclass - <Aggregate Geometry>

Subclasses

Definition

An instance of this DRM class is an aggregation of <Geometry Hierarchy> objects in which each component <Geometry Hierarchy> represents a branch of an Oct Tree. The octant represented by a branch is specified by the <Oct Tree Data> associated with that branch. The bounding region that the <Geometry Hierarchy> components occupy is defined by the <Spatial Domain> of the <Oct Tree Related Geometry>.

Primary Page in DRM Diagram:

• 4

Secondary Pages in DRM Diagram:

Example

1. Consider an Octtree that is represented in a transmittal by an <Oct Tree Related Geometry> instance. The lower left octant of the Octtree is a <Union Of Primitive Geometry> aggregated by the <Oct Tree Related Geometry> as follows:

   

FAQs

If an <Oct Tree Related Geometry> has less than 8 components, why is the data being organized under an <Oct Tree Related Geometry> at all?

An <Oct Tree Related Geometry> is used when an object in the hierarchy contains spatial components that occupy a certain octant. These octants might not contain <Primitive Geometry>, which is why this class can have less than 8 components.

Where is the <Spatial Domain> component?

<Oct Tree Related Geometry> automatically has a <Spatial Domain> component, because it is a <Geometry Hierarchy>. However, unlike other classes descended from <Geometry Hierarchy>, <Oct Tree Related Geometry> has a constraint stating that the <Spatial Domain> component is mandatory.

Constraints

• <<No Attribute Conflicts>>
• <<Non Crossing Aggregations>>
• <<Non Cyclic Aggregations>>
• <<Precedence of Attribute Set Index>>
• <<Non Crossing Associations>>
• <<Colour Mapping Restrictions>>
• <<Image Mapping Functions and Texture Coordinates>>
• <<Distinct Link Objects>>
• <<Oct Tree Related Organizing Principle>>

Associated by (one-way)(inherited)

• zero or one <Hierarchy Summary Item> instance (notes)
• zero or more <Reference Surface> instances (notes)

Associated with (two-way)(inherited)

• zero or more <Feature> instances (notes)
• zero or more <Geometry Hierarchy> instances (notes)

Composed of (two-way)(inherited)

• zero or more {ordered} <Attribute Set Index> instances
• zero or one <Classification Data> instance
• zero or more <Property Table> instances
• zero or more <Property Table Reference> instances
• zero or more <Property Value> instances
• zero or one <Reference Surface> instance
• zero or more <Sound Instance> instances
• zero or more <Base Level Of Detail Data> instances
• zero or one <Bounding Volume> instance
• zero or one <Centre Of Buoyancy> instance
• zero or one <Centre Of Mass> instance
• zero or one <Centre Of Pressure> instance
• zero or more <Collision Volume> instances (notes)
• zero or more <Colour> instances
• zero or one <Conformal Behaviour> instance
• zero or more <Geometry Topology Hierarchy> instances
• zero or more <Hierarchical Table> instances
• zero or more {ordered} <Image Mapping Function> instances
• zero or one <Light Rendering Properties> instance
• zero or more <Light Source> instances
• zero or one <LSR Transformation> instance
• zero or one <Overload Priority Index> instance
• zero or one <Perimeter Data> instance
• zero or one <Presentation Domain> instance
• zero or more <Property Description> instances
• zero or one <Rendering Priority Level> instance
• zero or one <Rendering Properties> instance
• zero or one <Spatial Domain> instance
• zero or one <Stamp Behaviour> instance

Composed of (two-way)

• a bounded set of 1..8 <Geometry Hierarchy> instances through <Oct Tree Data>

Composed of (two-way metadata)(inherited)

• zero or one <Time Constraints Data> instance
• zero or one <Access> instance
• zero or more <Browse Media> instances
• zero or more <Cross Reference> instances
• zero or one <Data Quality> instance
• zero or one <Keywords> instance
• zero or one <Point Of Contact> instance

Component of (two-way)(inherited)

• zero or more <Alternate Hierarchy Related Geometry> instances through <Hierarchy Data>
• zero or more <Animation Related Geometry> instances
• zero or more <Classification Related Geometry> instances through <Classification Data>
• zero or one <Environment Root> instance
• zero or one <Geometry Model> instance
• zero or more <Level Of Detail Related Geometry> instances through <Base Level Of Detail Data>
• zero or more <Oct Tree Related Geometry> instances through <Oct Tree Data>
• zero or more <Perimeter Related Geometry> instances through <Perimeter Data>
• zero or more <Quad Tree Related Geometry> instances through <Quad Tree Data>
• zero or more <Separating Plane Relations> instances through <Separating Plane Data>
• zero or more <Spatial Index Related Geometry> instances through <Spatial Index Data>
• zero or more <State Related Geometry> instances through <State Data>
• zero or more <Time Related Geometry> instances through <Time Constraints Data>
• zero or more <Union Of Geometry Hierarchy> instances

Inherited Field Elements

Notes

Associated with Notes

Feature

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

Geometry_Hierarchy

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

Hierarchy_Summary_Item

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

Reference_Surface

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

Composed of Notes

Collision_Volume

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

Fields Notes

unique_descendants

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

strict_organizing_principle

 If this value 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.