Class Name: Union Of Features
Subclasses
This DRM class is concrete and has no subclasses.
Definition
An instance of this DRM class is
an <Aggregate Feature> instance containing
a collection of
<Feature Representation> instances.
Primary Page in DRM Diagram:
Secondary Pages in DRM Diagram:
This class appears on only one page of the DRM class diagram.
Example
An airport can be represented as a
<Union Of Features> instance that includes
<Linear Feature> instances for the runways;
a <Point Feature> instance for the control tower;
and
<Areal Feature> instances for the terminal and
parking lots.
A <Union Of Features> instance can
represent a collection of <Areal Feature> instances
that represent all forested areas within the spatial extent of the
given <Environment Root> instance.
FAQs
-
What is the purpose of this class?
A <Union Of Features> instance provides a
general-purpose mechanism for grouping together a collection of
<Feature Representation> instances,
which may include
<Primitive Feature> instances,
<Feature Model Instance> instances,
and
<Aggregate Feature> instances. Note that
<Union Of Features> is the only subclass
of <Aggregate Feature> that can include
<Primitive Feature> instances as
direct components.
They therefore tend to be used at the lowest levels of a
<Feature Hierarchy> instance.
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)
Notes
Associated to Notes
An association between two
<Feature Representation> 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 between a
<Geometry Hierarchy> instance and a
<Feature Representation> 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 a
<Property Grid> instance and a
<Feature Representation> instance
indicates that the environmental object(s) represented by the
<Feature Representation> instance
and the <Property Grid> instance
(or some specific cell data within that
<Property Grid> instance) have the
semantic relationship indicated by the
<Base Association Data> link object
on the association relationship. Each associated
<Property Grid> instance indicates
whether the entire <Property Grid>
instance or only some specific cell data within it is participating
in the relationship in question.
Associated from Notes
An association between two
<Feature Representation> 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 between a
<Geometry Hierarchy> instance and a
<Feature Representation> 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 a
<Property Grid> instance and a
<Feature Representation> instance
indicates that the environmental object(s) represented by the
<Feature Representation> instance
and the <Property Grid> instance
(or some specific cell data within that
<Property Grid> instance) have the
semantic relationship indicated by the
<Base Association Data> link object
on the association relationship. Each associated
<Property Grid> instance indicates
whether the entire <Property Grid>
instance or only some specific cell data within it is participating
in the relationship in question.
Composed of Notes
The <Image Mapping Function> components
support texture mapping information
for geometry that is to be derived from the
<Aggregate Feature> instance
by the consumer.
These <Image Mapping Function>
instances shall use <Image Anchor>
components to specify the mapping.
A <Presentation Domain> component is needed for
<Aggregate Feature> instances that are
significant only for a particular domain, such as radar.
Fields Notes
If the value of the
unique_descendants
field is SE_TRUE, each
descendant shall be unique in the sense that it shall
appear in only one branch of this aggregation.
Each descendant is a <Feature Representation> instance
within the component tree rooted at the
<Aggregate Feature> instance.
If unique_descendants
is SE_FALSE, at least one
<Feature 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.
The union_reason field
specifies the reason why the
<Union Of Features> instance
was created to organize its components.
The ordering_reason
field specifies whether the ordering of the
<Feature Representation> components of the
<Union Of Features> instance is semantically
significant and, if so, what that significance is.
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