Table 6.68—DRM_Continuous_Level_Of_Detail_Related_Geometry

Property

Description

Superclass

·         <DRM Aggregate Geometry>

Class

·         <DRM Continuous Level Of Detail Related Geometry>

Subclass

·         none

Definition

An object of this class is used to represent continuous terrain or continuous adaptive terrain, by replacing a <DRM Polygon> with a set of fragmented <DRM Polygon>s that represent the terrain at a finer level of detail at close range (or alternatively, with a coarser level of detail at long range).

The general idea is that basic <DRM Polygon>s have fragmented <DRM Polygon>s within them, and those <DRM Polygon>s may have subsequent fragmentation.

Example(s)

·         A Continuous LOD node can be fragmented into one or more <DRM Polygon>s, and will then have zero or more Continuous LOD nodes as subnodes. Any Continuous LOD node that contains Continuous LOD nodes under it will have the terminating_node flag set to FALSE. The <DRM Union Of Primitive Geometry> node will contain <DRM Polygon> data. If a Continuous LOD node is encountered with the terminating_node flag set to TRUE, that means it only has a <DRM Union Of Primitive Geometry> node under it.

(Note that this example only shows two levels of polygon fragmentation. Each <DRM Continuous Level Of Detail Related Geometry> could contain component <DRM Continuous Level Of Detail Related Geometry>s, but that would make a huge picture. Only the idea is represented here.)

Inherited field elements

field_name

range

Field_Data_Type

unique_descendants1

 

Boolean

strict_organizing_principle2

 

Boolean

Field elements

field_name

range

Field_Data_Type

terminating_node3

 

Boolean

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>s

·         zero or more <DRM Geometry Hierarchy>s

Associated with (two-way)

·         none

Composed of (two-way) (inherited)

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

·         zero or more {ordered} <DRM Colour>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 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 <DRM Union Of Primitive Geometry>

·         zero or more <DRM Continuous Level Of Detail Related Geometry>s

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)

·         zero or one <DRM Continuous Level Of Detail Related Geometry>

Constraints

·         Colour mapping restrictions

·         Continuous LOD restrictions

·         Image mapping functions and texture coordinates

·         No attribute conflicts

·         Non-crossing aggregations

·         Non-crossing associations

·         Non-cyclic aggregations

·         Precedence of Attributre_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.

3 This flag identifies if the current level is the lowest level of fragmentation for a specific chain. Set to TRUE if no other <DRM Continuous Level of Detail Related Geometry> nodes are found below this chain's current level.

Class diagram

<DRM Continuous Level Of Detail Related Geometry>