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

Class Name: Time 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> components in which each branch is a representation of the same environmental entity at a different point in time, as indicated by the corresponding <Time Constraints Data> link object.

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 atmospheric forecast data organized using nested <Time Related Geometry> instances as depicted in Figure 6.71:

    Time Related Geometry, atmospheric forecast example

    Figure 71 — <DRM Time Related Geometry> atmospheric forecast example

    The <Classification Data> instances specify to what each <Time Related Geometry> instance corresponds. The outer <Time Related Geometry> instance corresponds to base forecast times, while the inner <Time Related Geometry> instance corresponds to forecast taus.

    In the forecast world, models are run starting at some base starting time (for example, at 0Z and 12Z). The model then produces forecasts at several deltas after the base starting time (for example, at 6, 12, 18, and 24 hours). These are known as forecast taus.

    Consequently, forecast models are run at 0Z and 12Z, and each produces a 24 hour forecast, the following overlap is obtained.

        16 Nov                 17 Nov                     18 Nov
        0Z   +6    +12   +18   +24
                   12Z   +6   +12    +18    +24
                               0Z    +6     +12    +18    +24
                                      ....
    

    To uniquely identify a forecast, the base forecast time and the delta (tau) are required. This is why nested <Time Related Geometry> instances have been used in this example; one <Time Related Geometry> instance defines the base forecast time, while its <Time Related Geometry> component defines the forecast tau.

    This approach is needed only if multiple forecasts with overlapping forecasts are included in the transmittal. If instead the analysis (0Z) and +6 forecasts from each forecast are used, the following is obtained.

        16 Nov             17 Nov
        0Z   +6  12Z  +6   0Z   +6   12Z   +6  ...
    
  2. Consider a <Model> instance representing a deciduous tree. The colour of the leaves of the tree depends on the time of year, or season. Consequently, a data provider to whom this is important organizes a tree <Model> instance using a <Time Related Geometry> instance along the lines depicted in Figure 6.72. Only the autumn representation of the <Model> instance is shown, but other branches are present for the other seasons.

    Time Related Geometry, deciduous tree example

    Figure 72 — <DRM Time Related Geometry> deciduous tree 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_Time_Data_Type time_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.

time_data_type

The time_data_type field specifies the subclass of <Base Time Data> of which each <Time Constraints Data> link object in the given organization is to be composed.


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Last updated: July 26, 2006 Copyright © 2006 SEDRIS