Table 6

This is an abstract DRM class that specifies a collection of <DRM Primitive Geometry> or <DRM Geometry Hierarchy> instances, organized according to some organizing principle specific to the particular subclass of <DRM Aggregate Geometry> being considered..

For most subclasses of <DRM Aggregate Geometry>, each individual branch of the aggregation is explicitly identified by a distinct link object. The various subclasses provide different mechanisms for organizing <DRM Geometry> instances, which include:

ALTERNATE_HIERARCHY:
Each branch is a <DRM Geometry Hierarchy> with a different <DRM Hierarchy Data> value, representing different ways of organizing the same collection of <DRM Geometry> instances.
ANIMATION:
Each branch is a <DRM Geometry Hierarchy>, representing a different frame in an animation sequence. This organizing principle has no counterpart on the <DRM Feature> side.
CLASSIFICATION:
Each branch is a <DRM Geometry Hierarchy> with a different DRM_Classification Data instance, representing either a different thematic layer or different classification of DRM_Geometry instances (e.g., roads, railroads) within a single thematic layer.
CONTINUOUS_LEVEL_OF_DETAIL:
Each branch is either a <DRM Union Of Primitive Geometry> (usually a collection of <DRM Polygon>s), or 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). Used to represent continuous terrain or continuous adaptive terrain. This mechanism has no counterpart on the <DRM Feature> side.
LEVEL_OF_DETAIL:
Each branch is a <DRM Geometry Hierarchy> with a different, (but possibly overlapping) <DRM Base Level of Detail Data> instance, representing alternatives that shall be used at a specific level of detail.
OCT_TREE:
The <DRM Aggregate Geometry> represents an oct_tree, in which each branch is a <DRM Geometry Hierarchy> representing an octant within the oct_tree, as identified by its <DRM Oct Tree Data> instance.
PERIMETER:
Each branch is a <DRM Geometry Hierarchy> that is located within a different cell of an irregular spatial index, as defined by its <DRM Perimeter Data> instance.
QUAD_TREE:
The <DRM Aggregate Geometry> represents a quad_tree, in which each branch is a <DRM Geometry Hierarchy> representing an quadrant within the quad_tree, as identified by its <DRM Quad Tree Data> instance.
SEPARATING_PLANE:
Each branch is a <DRM Separating Plane Relations>, each branch of which is a <DRM Geometry Hierarchy> instance that is on either the positive or negative side of the associated <DRM Separating Plane>, as indicated by the <DRM Separating Plane Data> instance for that branch. This organizing principle has no counterpart on the <DRM Feature> side.
SPATIAL_INDEX:
The <DRM Aggregate Geometry> represents a regularly spaced spatial index grid, in which each branch is a <DRM Geometry Hierarchy> instance representing a different cell within the spatial index.
STATE:
The <DRM Aggregate Geometry> represents something that can take on different state values for a specified EDCS Attribute Code (the state_tag, which shall have the "state-related" property). Each branch is a <DRM Geometry Hierarchy> instance with a different <DRM State Data> instance, representing an alternative that shall be used to represent the <DRM Aggregate Geometry> when it takes on the specified state value.
TIME:
The <DRM Aggregate Geometry> represents something that has different representations for different time periods, so that each branch is a <DRM Geometry Hierarchy> instance with a distinct (though possibly overlapping) <DRM Time Constraints Data> instance, representing an alternative that shall be used for the time period specified by its <DRM Time Constraints Data>.
UNION_OF_GEOMETRY_HIERARCHY:
Each branch is a <DRM Geometry Hierarchy>. The reason for organizing them into separate components is only minimally specified. This mechanism's counterpart on the <DRM Feature> side is <DRM Union of Features>.
UNION_OF_PRIMITIVE_GEOMETRY:
Each branch is a <DRM Primitive Geometry> instance. A <DRM Primitive Geometry> can be included in a transmittal only by means of <DRM Union Of Primitive Geometry> instances. This mechanism's counterpart on the <DRM Feature> side is <DRM Union of Features>.

Example(s)

· A 500 meter by 500 meter patch of gridded terrain.

· A 10 Km by 20 Km triangulated irregular network of <DRM Polygon>s.

· A populated rectangular region that is one node of a quad tree of <DRM Aggregate Geometry> objects.

· Atmosphere over a certain region is stored for two different times of day.

Inherited field elements

field_name	range	Field_Data_Type
none

Field elements

field_name	range	Field_Data_Type
unique_descendant¹		Boolean
strict_organizing_principle²		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 Classification Data>

· 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 more <DRM Sound Instance>s

· zero or one <DRM Time Constraints Data>

Composed of (two-way)

· zero or one <DRM Bounding Volume>

· one or more <DRM Camera Point>s

· zero or one <DRM Centre Of Buoyancy>

· zero or one <DRM Centre Of Mass>

· zero or one <DRM Centre Of Pressure>

· zero or more <DRM Collision Volume>s

· zero or more {ordered} <DRM_Colour>s

· zero or one <DRM Conformal Behaviour>³

· 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 Property>s

· 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 one <DRM Rendering Priority Level>

· zero or one <DRM Rendering Properties>

· zero or one <DRM Spatial Domain>

· zero or one <DRM Stamp Behaviour>⁴

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

· 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