The SEDRIS Data Representation Model
APPENDIX A - Classes
Classification Related Geometry

Class Name: Classification Related Geometry

Superclass - <Aggregate Geometry>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance of this DRM class is an aggregation of <Geometry Hierarchy> instances, organized according to their EDCS Classification Codes (ECCs), such that each component <Geometry Hierarchy> instance represents

  1. a different thematic layer, or
  2. a different classification of <Geometry> instances within a single thematic layer.
Each branch of a <Classification Related Geometry> instance therefore has a <Classification Data> instance associated with it as a link object, specifying its (possibly elaborated) classification.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

This class appears on only one page of the DRM class diagram.

Example

  1. A surface area consisting of forest and water is represented as a <Classification Related Geometry> with strict_organizing_principle set to SE_TRUE, containing two <Union Of Primitive Geometry> components. The first, containing the forest polygons, has a <Classification Data> link object with a tag value of ECC_FOREST, while the second, containing the water polygons, has a <Classification Data> link object with a tag value of ECC_WATER.

  2. In the first example, suppose a road runs through the forest. Then the forest <Union Of Primitive Geometry> can be replaced with another <Classification Related Geometry> having 2 branches, one classified as ECC_ROAD and the other as ECC_FOREST, and the strict_organizing_principle flag mentioned in example 1 is set to SE_FALSE, because the forest branch at the coarse level contains non-forest (that is, road) geometry.

FAQs

What is the purpose of this class?
<Classification Related Geometry> exists to provide a mechanism for hierarchically organizing <Geometry> instances according to their (possibly elaborated) classification.

Constraints

Associated by (one-way)(inherited)

Associated with (two-way)(inherited)

Composed of (two-way)(inherited)

Composed of (two-way)

Composed of (two-way metadata)(inherited)

Component of (two-way)(inherited)

Inherited Field Elements

SE_Boolean unique_descendants; (notes)
SE_Boolean strict_organizing_principle; (notes)

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.
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Last updated: May 15, 2003 Copyright © 2003 SEDRIS™