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

Class Name: Perimeter Related Geometry

Superclass - <Aggregate Geometry>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance of this DRM class is an <Aggregate Geometry> instance that spatially organizes its <Geometry Hierarchy> components into a collection of (potentially) irregularly shaped regions, each defined by a <Perimeter Data> link object. That is, each <Geometry Hierarchy> component is contained within the perimeter area specified by the <Perimeter Data> link object associated with that component.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

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

Example

  1. Consider a <Perimeter Related Geometry> instance PRG with two branches, each with a distinct <Union Of Primitive Geometry> component as depicted in Figure 6.36.

    Perimeter Related Geometry, Example 1

    Figure 36 — <DRM Perimeter Related Geometry> example, strict_organizing_principle = TRUE

    By the constraint specified in <<Perimeter Related Organizing Principle>>, at least one of the vertices of A shall fall within the region described by the <Perimeter Data> link object PD1. If PRG has strict_organizing_principle = SE_TRUE, all the vertices of A do so.

  2. Consider a second <Polygon> instance B, a sibling of A within UPG1 as depicted in Figure 6.37.

    Perimeter Related Geometry, Example 2

    Figure 37 — <DRM Perimeter Related Geometry> example, strict_organizing_principle = FALSE

    B falls on the boundary dividing the regions described by PD1 and PD2, such that at least one of B's vertices falls within PD1 and at least one of B's vertices falls PD2.

    By the constraint specified in <<Perimeter Related Organizing Principle>>, the strict_organizing_principle flag of PRG shall be set to SE_FALSE, since branches are present that do not fully contain their DRM objects.

FAQs

May the regions defined by the components of a <Perimeter Related Geometry> instance overlap?

See <<Perimeter Related Organizing Principle>>

May the same <Geometry Representation> be contained within more than one of the components of a <Perimeter Related Geometry> instance?

See <<Perimeter Related Organizing Principle>>

Does each of the components of a <Perimeter Related Geometry> instance form an independent topological surface?

Normally, yes. In this case, each <Geometry Hierarchy> component has its own <Geometry Topology Hierarchy> component. However, the <Geometry Topology> instances in all the components may also form a single topological surface, in which case only the <Perimeter Related Geometry> instance itself has such a topology hierarchy.

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; 9
SE_Boolean strict_organizing_principle; 10

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> link object 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> link object 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> link object 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> link object on the association relationship.


Hierarchy_Summary_Item

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


Reference_Surface

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

Composed of Notes


Collision_Volume

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


LSR_Transformation

An <Aggregate Geometry> instance can have an <LSR Transformation> component only when the <Aggregate Geometry> instance is within the scope of an LSR 3D SRF.

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 <Aggregate Geometry> instance 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 26, 2006 Copyright © 2006 SEDRIS