Class Name: Alternate Hierarchy Related Features

Superclass - Aggregate Feature

Definition

An aggregation of Feature Hierarchies in which each component Feature Hierarchy is an alternate representation of the same environmental entity. The Feature Hierarchy Data link object attached to each component indicates how it is organized.

Primary Page in DRM Diagram:

• 8

Example

1. The collection of Features representing a specific spatial region must be accessed efficiently both by location (e.g., for display), and by classification (i.e., roads, then rivers, then vegetation, etc.). To accommodate this, an Alternate Hierarchy Related Features object with two components can be used, in which one component consists of a Quad Tree Related Features object, which organizes the Features by location, and the other component consists of a Classification Related Features object, which organizes the features by EDCS Classification Code (ECC).

FAQs

What is the purpose of this class?

This class allows a single collection of Features to be hierarchically organized in two or more different ways. In one component, the Features might be organized spatially, while in another component they might be organized by classification. This provides two (or more) different access paths to the same objects, each organized to be efficient with respect to a different access pattern.

Constraints

• Image Mapping Functions and Texture Coordinates
• No Attribute Conflicts
• Non Crossing Aggregations
• Non Crossing Associations
• Precedence of Attribute Set Index
• Non Cyclic Aggregations
• Distinct Link Objects

Associated by (one-way)(inherited)

• optionally, a Hierarchy Summary Item

Associated with (two-way)(inherited)

• optionally, some Features
• optionally, some Geometry Hierarchies
• optionally, some Property Grids

Composed of (one-way)(inherited)

• optionally, some {ordered} Attribute Set Indices
• optionally, a Classification Data
• optionally, some Colors
• optionally, some {ordered} Image Mapping Functions (notes)
• optionally, some Labels
• optionally, some Property Tables
• optionally, some Property Table References
• optionally, some Property Values
• optionally, a Rendering Priority Level
• optionally, a Spatial Domain
• optionally, a Reference Surface
• optionally, some Sound Instances
• optionally, some Property Descriptions

Composed of (two-way)(inherited)

• optionally, some Topology Hierarchies

Composed of (two-way)

• an unbounded set of Feature Hierarchies[2...] through Feature Hierarchy Data

Composed of (one-way metadata)(inherited)

• optionally, an Access
• optionally, some Browse Graphics
• optionally, some Cross References
• optionally, a Data Quality
• optionally, a Keywords
• optionally, a Point of Contact
• optionally, a Time Constraints Data

Component of (two-way)(inherited)

• optionally, some Union of Features
• optionally, some Alternate Hierarchy Related Features through Feature Hierarchy Data
• optionally, some Classification Related Features through Feature Classification Data
• optionally, an Environment Root
• optionally, a Feature Model
• optionally, some Time Related Features through Feature Time Constraints Data
• optionally, some Level of Detail Related Features through Feature Level of Detail Data
• optionally, some Oct Tree Related Features through Feature Oct Tree Data
• optionally, some Perimeter Related Features through Feature Perimeter Data
• optionally, some Quad Tree Related Features through Feature Quad Tree Data
• optionally, some Spatial Index Related Features through Feature Spatial Index Data
• optionally, some State Related Features through Feature State Data

Inherited Field Elements

Notes

Composed of Notes

Image_Mapping_Function

 Added to support "attributes for derived objects."
 That is, these components are used only to specify
 texture mapping information for geometry that
 is derived from the <Feature> by the consumer.
 These <Image Mapping Functions> must use
 <Image Anchor> components to specify the mapping.

Fields Notes

unique_descendants

 If true, then for any object that exists 'below' this aggregation,
 each object will appear in only one 'branch' of this aggregation.
 If false, then objects may appear in multiple 'branches' of this
 aggregation.

independent_topologies

 If true, then each 'branch' from this aggregation is its own,
 independent topology.  If false, then all of the branches exist
 within the same topology.

strict_organizing_principle

 If true, then each 'branch' strictly follows the rules of this
 aggregation.  If false, then each 'branch' might bend the rules a bit.
 For example, if this is a spatial aggregation, than a value of true
 indicates that objects will *not* cross the spatial extents defined
 by this aggregation relationship, and a value of false indicates
 that objects might cross those bounds.  For another example, if this
 is a time-based aggregation, then a value of true indicates that all
 branches will only contain data valid for the times specified for
 each branch, and a value of false indicates that the branches have
 the option of including data that falls outside of the specified
 time ranges for that branch.