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 specifies an aggregation of <Geometry Hierarchy> instances, organized according to their ECCs, such that each component <Geometry Hierarchy> instance represents

  1. a different thematic layer, or
  2. a different classification of <Geometry Representation> 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 Representation> instances according to their (possibly elaborated) classification.

Constraints

Associated to (one-way) (inherited)

Associated by (one-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 to Notes


Feature_Representation

 An association between a <Feature Representation> instance
 and a <Geometry Hierarchy> instance indicates that the
 environmental object(s) that they represent have the
 semantic relationship indicated by the <Base Association Data>
 instance on the association relationship.

Geometry_Hierarchy

 An association between two <Geometry Hierarchy> instances
 indicates that the environmental object(s) that they
 represent have the semantic relationship indicated by
 the <Base Association Data> instance on the association
 relationship.

Associated from Notes


Feature_Representation

 An association between a <Feature Representation> instance
 and a <Geometry Hierarchy> instance indicates that the
 environmental object(s) that they represent have the
 semantic relationship indicated by the <Base Association Data>
 instance on the association relationship.

Geometry_Hierarchy

 An association between two <Geometry Hierarchy> instances
 indicates that the environmental object(s) that they
 represent have the semantic relationship indicated by
 the <Base Association Data> instance on the association
 relationship.

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 the value of the unique_descendants field is SE_TRUE, each
 descendant of this aggregation,
 that is, each <Geometry Representation> 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 Representation> instance
 appears in more than one branch of the aggregation.

strict_organizing_principle

 If the value of the strict_organizing_principle field 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: July 16, 2004 Copyright © 2004 SEDRIS™