Class Name: Union Of Primitive Geometry
Subclasses
This DRM class is concrete and has no subclasses.
Definition
An instance of this DRM class is a
<Union Of Geometry> instances
that is composed solely of
<Primitive Geometry> instances.
Primary Page in DRM Diagram:
Secondary Pages in DRM Diagram:
Example
Consider a geometric representation of an airport runway in which the
runway surface is represented by a layer of polygons, overlaid by stripes
(decal polygons). To ensure that the necessary rendering order is followed,
the data provider creates a <Union Of Primitive Geometry>
instance U and attaches each <Polygon> instance as a component
of U, in order of increasing relative rendering priority. The
<Polygon> instance with the lowest relative rendering priority
is attached first. After all the <Polygon> instances in the
underlying pavement have been attached, the <Polygon> instances
used to decal the pavement are attached in the order
in which they will be rendered.
If a specific method is used for the ordering, the data provider specifies
it in the ordering_reason field of U. In
this case, the data was created for a Z-buffer rendering system that
supports layers, so ordering_reason is set
to
SE_ORDREAS_LAYERED_HIGH_QUALITY_RENDERING.
A <Union Of Primitive Geometry> instance is a collection
of <Polygon> instances making up the representation of a
fire hydrant.
A <Union Of Primitive Geometry> instance is a 10 kilometre
by 20 kilometre triangulated irregular network of
<Polygon> instances.
FAQs
No FAQs supplied.
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 an <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
Component of (two-way)
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.
The union_reason field
specifies the reason why the
<Union Of Geometry> instance
was created to organize its components.
The ordering_reason
field specifies whether the ordering of the
<Geometry Representation> components of the
<Union Of Geometry> instance is semantically
significant and, if so, what that significance is.
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