Class Name: Alternate Hierarchy Related Geometry
Subclasses
This DRM class is concrete and has no subclasses.
Definition
An instance of this DRM class specifies an aggregation of
<Geometry Hierarchy>
instances, in which each
<Geometry Hierarchy> component
is an alternate representation of
the same environmental entity, and the corresponding
<Hierarchy Data>
link object indicates why that particular alternate representation
was provided.
Primary Page in DRM Diagram:
Secondary Pages in DRM Diagram:
This class appears on only one page of the DRM class diagram.
Example
Consider a collection of
<Geometry Representation> instances
representing a specific spatial region, for which there is a
requirement that the
<Geometry Representation> instances
shall be efficiently accessible both by location and by classification
(such as ECC_ROAD, ECC_RIVER, ECC_VEGETATION).
To satisfy this requirement, the data provider has chosen to use
an <Alternate Hierarchy Related Geometry>
instance with two components, in which one component (in this example, a
<Spatial Index Related Geometry> component) organizes the
<Geometry Representation> instances spatially,
while a second component
(a <Classification Related Geometry> component) organizes
the <Geometry Representation> instances by ECC.
The <Alternate Hierarchy Related Geometry> instance is
related to its <Spatial Index Related Geometry> component
through a <Hierarchy Data> link object with
alternate_representation_reason
containing the string "accessibility by location". The
<Alternate Hierarchy Related Geometry> instance is related
to its <Classification Related Geometry> component through a
<Hierarchy Data> link object with
alternate_representation_reason
containing the string "accessibility by classification".
FAQs
-
What is the purpose of this class?
This class allows a single collection of
<Geometry Representation> instances
to be hierarchically organized in two or more different ways. In one
branch, the <Geometry Representation>
instances might be organized spatially, while in another,
they might be organized by classification. This provides two (or more)
different access paths to the same objects, each organized to be
efficient with respect to a different access pattern.
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)
- zero or more <Alternate Hierarchy Related Geometry> instances, each through the use of a <Hierarchy Data> link object
- zero or more <Animation Related Geometry> instances
- zero or more <Classification Related Geometry> instances, each through the use of a <Classification Data> link object
- zero or one <Environment Root> instance
- zero or one <Geometry Model> instance
- zero or more <LOD Related Geometry> instances, each through the use of a <Base LOD Data> link object
- zero or more <Octant Related Geometry> instances, each through the use of a <Octant Data> link object
- zero or more <Perimeter Related Geometry> instances, each through the use of a <Perimeter Data> link object
- zero or more <Quadrant Related Geometry> instances, each through the use of a <Quadrant Data> link object
- zero or more <Separating Plane Relations> instances, each through the use of a <Separating Plane Data> link object
- zero or more <Spatial Index Related Geometry> instances, each through the use of a <Spatial Index Data> link object
- zero or more <State Related Geometry> instances, each through the use of a <State Data> link object
- zero or more <Time Related Geometry> instances, each through the use of a <Time Constraints Data> link object
- zero or more <Union Of Geometry Hierarchy> instances
Notes
Associated to Notes
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.
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
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.
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.
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.
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
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.
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
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.
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.
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