Class Name: Quad Tree Related Geometry

Superclass - <Aggregate Geometry>

Subclasses

Definition

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

Primary Page in DRM Diagram:

• 4

Secondary Pages in DRM Diagram:

Example

1. Consider a representation of a region of terrain that is organized into quadrants, where the upper-right quadrant consists of ocean, and the other three quadrants consist of the terrain bordering the ocean. The ocean quadrant is not represented in the producer's system. The region is represented in SEDRIS by a <Quad Tree Related Geometry> with 3 component <Union Of Primitive Geometry>. (Since the remaining quadrant had no <Polygon> instances, it was not represented.)

   

2. Consider a Quadtree that is represented in a transmittal by a <Quad Tree Related Geometry> instance. The southwest quadrant of the Quadtree is a <Union Of Primitive Geometry> aggregated by the <Quad Tree Related Geometry> as follows:

   

FAQs

If a <Quad Tree Related Geometry> has less than 4 components, why is the data being organized under a <Quad Tree Related Geometry> at all?

A <Quad Tree Related Geometry> is used when an object in the hierarchy contains spatial components that occupy a certain quadrant. These quadrants might not contain <Primitive Geometry> objects, which is why instances of this class can have less than four components.

Where is the <Spatial Domain> component?

<Quad Tree Related Geometry> automatically has a <Spatial Domain> component, component, because it is a <Geometry Hierarchy>. Unlike <Geometry Hierarchies> in general, however, <Quad 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>>
• <<Quad 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..4 <Geometry Hierarchy> instances through <Quad 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.