Table 6.298—DRM_Time_Related_Geometry

Property

Description

Superclass

·         <DRM Aggregate Geometry>

Class

·         <DRM Time Related Geometry>

Subclass

·         none

Definition

An object of this DRM class specifies an aggregation of <DRM Geometry Hierarchy>s that are differentiated by the <DRM Time Constraints Data> link objects attached to the aggregation relationships used to reach the <DRM Geometry Hierarchy> objects.

Example(s)

·         Riverbed could be immersed, wet or dry depending on the time of the year.

·         Atmospheric forecast data is organized using nested <DRM Time Related Geometry>.

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

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

Consequently, if you run forecast models at 0Z and 12Z, and each produces a 24 hour forecast, the following overlap occurs:

 16 Nov               17 Nov              18 Nov

 0Z  +6  +12  +18  +24
         12Z   +6  +12  +18  +24
                    0Z   +6  +12  +18  +24
                                            ...

Therefore, to uniquely identify a forecast, the base forecast time and the delta (tau) need to be specified. This is why nested <DRM Time Related Geometry> has been used in this example; one <DRM Time Related Geometry> defines the base forecast time, while its component <DRM Time Related Geometry> defines the forecast tau.

Note that this approach is needed only if multiple forecasts with overlapping forecasts are included in the transmittal. If only the analysis (0Z) and +6 forecasts from each forecast are used, then no overlap occurs:

 16 Nov             17 Nov              18 Nov

 0Z   +6  12Z  +6   0Z   +6   12Z   +6  ...

·         Consider a <DRM Model> of a deciduous tree. The colour of the tree's leaves depends on the time of year, or season. Consequently, a data provider might organize a tree <DRM Model> using a <DRM Time Related Geometry> along the following lines. (Only the autumn representation of the <DRM Model> might be depicted, but other branches would be present for the other seasons).

Inherited field elements

field_name

range

Field_Data_Type

unique_descendants1

 

Boolean

strict_organizing_principle2

 

Boolean

Field elements

field_name

range

Field_Data_Type

time_data_type

 

Time_Data_Type

Associated to (one-way) (inherited)

·         none

Associated to (one-way)

·         none

Associated by (one-way) (inherited)

·         zero or one <DRM Hierarchy Summary Item>

·         zero or more <DRM Reference Surface>s

Associated by (one-way)

·         none

Associated with (two-way) (inherited)

·         zero or more <DRM Feature>

·         zero or more <DRM Geometry Hierarchy>

Associated with (two-way)

·         none

Composed of (two-way) (inherited)

·         zero or more {ordered} <DRM Attribute Set Index>s

·         zero or more <DRM Base Level Of Detail Data>s

·         zero or one <DRM Bounding Volume>

·         zero or one <DRM Centre Of Buoyancy>

·         zero or one <DRM Centre Of Mass>

·         zero or one <DRM Centre Of Pressure>

·         zero or one <DRM Classification Data>

·         zero or more {ordered} <DRM Colour>s

·         zero or more <DRM Collision Volume>s

·         zero or one <DRM Conformal Behaviour>

·         zero or more <DRM Geometry Topology Hierarchy>s

·         zero or more <DRM Hierarchical Table>s

·         zero or more {ordered} <DRM Image Mapping Function>s

·         zero or one <DRM Light Rendering Properties>

·         zero or more <DRM Light Source>s

·         zero or one <DRM LSR Transformation>

·         zero or one <DRM Overload Priority Index>

·         zero or one <DRM Perimeter Data>

·         zero or one <DRM Point Of Contact>

·         zero or one <DRM Presentation Domain>

·         zero or more <DRM Property Description>s

·         zero or more <DRM Property Table>s

·         zero or more DRM¸Property Table Reference>s

·         zero or more <DRM Property Value>s

·         zero or one <DRM Reference Surface>

·         zero or one <DRM Rendering Priority Level>

·         zero or one <DRM Rendering Properties>

·         zero or more <DRM Sound Instance>s

·         zero or one <DRM Spatial Domain>

·         zero or one <DRM Stamp Behaviour>

·         zero or one <DRM Time Constraints Data>

Composed of (two-way)

·         one or more <DRM Geometry Hierarchy> through <DRM Time Constraints Data>

Composed of (two-way metadata) (inherited)

·         zero or one <DRM Access>

·         zero or more <DRM Browse Media>s

·         zero or one <DRM Citation>

·         zero or more <DRM Cross Reference>s

·         zero or one <DRM Data Quality>

·         zero or one <DRM Description>

·         zero or one <DRM Keywords>

·         zero or one <DRM Point Of Contact>

Composed of (two-way metadata)

·         none

Component of (two-way) (inherited)

·         zero or more <DRM Alternate Hierarchy Related Geometry>s through <DRM Hierarchy Data>s

·         zero or more <DRM Animation Related Geometry>s

·         zero or more <DRM Classification Related Geometry>s through <DRM Classification Data>s

·         zero or one <DRM Environment Root>

·         zero or one <DRM Geometry Model>

·         zero or more <DRM Level Of Detail Related Geometry>s through <DRM Base Level Of Detail Data>s

·         zero or more <DRM Oct Tree Related Geometry>s through <DRM Oct Tree Data>s

·         zero or more <DRM Perimeter Related Geometry>s through <DRM Perimeter Data>s

·         zero or more <DRM Quad Tree Related Geometry>s through <DRM Quad Tree Data>s

·         zero or more <DRM Separating Plane Relations>s through <DRM Separating Plane Data>s

·         zero or more <DRM Spatial Index Related Geometry>s through <DRM Spatial Index Data>s

·         zero or more <DRM State Related Geometry>s through <DRM State Data>s

·         zero or more <DRM Time Related Geometry>s through <DRM Time Constraints Data>s

·         zero or more <DRM Union Of Geometry Hierarchy>s

Component of (two-way)

·         none

Constraints

·         Colour mapping restrictions

·         Distinct link objects

·         Image mapping functions and texture coordinates

·         No attribute conflicts

·         Non-crossing aggregations

·         Non-crossing associations

·         Non-cyclic aggregations

·         Precedence of Attribute_Set_Index

Notes

1 If TRUE, for any object that exists 'below' this aggregation, each object will appear in only one 'branch' of this aggregation. If FALSE, objects may appear in multiple 'branches' of this aggregation.

2 If TRUE, each 'branch' strictly follows the rules of this aggregation. If FALSE, each 'branch' might bend the rules a bit. For example, if this is a spatial aggregation, a value of TRUE indicates that objects will not cross the spatial extents defined by this aggregation relationship, and a value of FALSE indicates that objects might cross those bounds. For another example, if this is a time-based aggregation, a value of TRUE indicates that all branches will only contain data valid for the times specified for each branch, and a value of FALSE indicates that the branches have the option of including data that falls outside of the specified time ranges for that branch.

Class diagram

<DRM Time Related Geometry>