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

Class Name: LOD 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> components in which each <Geometry Hierarchy> component is an alternate representation of the same entity at a different level of detail. Each <Geometry Hierarchy> component is a collection of <Geometry Representation> instances with a different, possibly overlapping, <Base LOD Data> link object field value, representing an alternative that should be used at different levels of such distinctions as viewing ranges, map scales, or spatial resolution.

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 <Model> instance representing a house, organized based on viewing ranges. If the viewer is farther away than 1000 metres, the house is not visible. From 500 metres to 1000 metres, the roof and walls are visible but not in great detail. From 0 metres to 500 metres, the windows and door become visible. Consequently, the <Model> instance is visible at two distance-related levels of detail: 0-500 metres, and 500-1000 metres, as depicted in Figure 31.

    LOD Related Geometry, Example 1

    Figure 31 — <DRM LOD Related Geometry> house example

    For the more detailed 0.0 - 500.0 metres, different "wall" <Model> instances are instanced for the walls containing the windows and doors; otherwise, the structure of the two levels, for this example, is similar.

  2. Three <Model> instances representing a given building are created, each with different <Polygon> instance counts. The most accurate representation is useful up to a viewing distance of 1 kilometre, the second from 1 kilometre to 2 kilometres, and the third for 2 kilometres to 5 kilometres.

    To indicate this, a fourth <Model> instance can be created as depicted in Figure 32:

    LOD Related Geometry, Example 2

    Figure 32 — <DRM LOD Related Geometry> building example

FAQs

No FAQs supplied.

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

Field Elements

SE_LOD_Data_Type

lod_data_type;

11

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.

lod_data_type

The lod_data_type field specifies the subclass of <Base LOD Data> of each link object in the given organization.

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Last updated: June 24, 2007 Copyright © 2007 SEDRIS™