The SEDRIS Data Representation Model
APPENDIX A - Classes
Quadrant Related Geometry
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Class Name: Quadrant 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> objects in
which each component <Geometry Hierarchy>
represents a branch of a Quadrant. The quadrant represented by a branch is
specified by the <Quadrant Data>
associated with that branch. The bounding region that the
<Geometry Hierarchy> components occupy is
defined by the <Spatial Extent> of the
<Quadrant Related Geometry>.
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 representation of a region of terrain that is organized into
quadrants, where the upper-right quadrant consists of ocean, and the
other three quadrants consist of the terrain bordering the ocean. The
ocean quadrant is not represented in the producer's system. The region
is represented in SEDRIS by a
<Quadrant Related Geometry> instance
with three
<Union Of Primitive Geometry>
instances. (Since the remaining quadrant had no
<Polygon> instances, it was not represented.)
Consider a quadtree that is represented in a transmittal by
a <Quadrant Related Geometry>
instance. The southwest quadrant of the quadtree is a
<Union Of Primitive Geometry>
aggregated by the
<Quadrant Related Geometry>
as follows:
FAQs
- If a <Quadrant Related
Geometry> has less than 4 components, why is the data being organized
under a <Quadrant Related
Geometry> at all?
A <Quadrant Related Geometry>
is used when an object in the hierarchy contains spatial components that
occupy a certain quadrant. These quadrants might not contain
<Primitive Geometry> objects,
which is why instances of this class can have less than four components.
- Where is the <Spatial Extent> component?
<Quadrant Related Geometry>
automatically has a <Spatial Extent> component,
component, because it is a <Geometry
Hierarchy>. Unlike <Geometry Hierarchies>
in general, however, <Quadrant
Related Geometry> has a constraint stating that the
<Spatial Extent> component is mandatory.
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 with a <Hierarchy Data> link object
- zero or more <Animation Related Geometry> instances
- zero or more <Classification Related Geometry> instances, each with 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 with a <Base LOD Data> link object
- zero or more <Octant Related Geometry> instances, each with a <Octant Data> link object
- zero or more <Perimeter Related Geometry> instances, each with a <Perimeter Data> link object
- zero or more <Quadrant Related Geometry> instances, each with a <Quadrant Data> link object
- zero or more <Separating Plane Relations> instances, each with a <Separating Plane Data> link object
- zero or more <Spatial Index Related Geometry> instances, each with a <Spatial Index Data> link object
- zero or more <State Related Geometry> instances, each with a <State Data> link object
- zero or more <Time Related Geometry> instances, each with 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>
instance 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> instance 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>
instance 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> instance on the association
relationship.
An association from a <Hierarchy Summary Item> instance to a
<Geometry Hierarchy> indicates that the <Hierarchy Summary Item>
summarizes that <Geometry Hierarchy>.
An association from a <Reference Surface> instance to a
<Geometry Hierarchy> indicates that the <Geometry Hierarchy>
organizes the geometric objects that specify the resolution
surface of the <Reference Surface>.
Composed of Notes
In the case where multiple <Collision Volume> components are
specified for a given <Aggregate Geometry>, the union of the
volumes thus specified is used in collision detection.
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 given <Aggregate Geometry>, 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.
Prev: Quadrant Related Features.
Next: Reference Origin.
Up:Index.
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Last updated: July 16, 2004
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Copyright © 2004 SEDRIS™
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