Class Name: Spatial Index Related Geometry

Superclass - Aggregate Geometry

Definition

An aggregation of Geometry Hierarchies in which each component Geometry Hierarchy represents a different tile within a spatially indexed (tiled) organization of Primitive Geometry objects within a SEDRIS transmittal. The Geometry Spatial Index Data link object attached to each component Geometry Hierarchy indicates the tile that it represents.

Primary Page in DRM Diagram:

• 4

Example

1. See Spatial Index Related Organizing Principle, example #1.

2. Consider an Environment Root describing a terrain surface that is a mix of grids and Polygons, organized by spatial indexing into 9 cells.

             -------------------
             |  A  |  B  |  C  |
             -------------------
             |  D  |  E  |  F  |
             -------------------
             |  G  |  H  |  I  |
             -------------------
   

   All cells except H are grids (represented in SEDRIS as Property Grids) captured at 1 level of detail. Cell H consists of Polygons.

   This would be represented as

                               <Environment Root>
                                       <>
                                       |
                                       |
                        <Spatial Index Related Geometry>
                                       <>
                                       |------- <GD Location 2D>
                                       |         (0,0)
                                       |
        -----------------------------------------------------------------
        |       |       |       |       |       |       |       |       |
        |-GSID  |-GSID  |-GSID  |-GSID  |-GSID  |-GSID  |-GSID  |-GSID  |-GSID
        | (1,1) | (1,2) | (1,3) | (2,1) | (2,2) | (2,3) | (3,1) | (3,2) | (3,3)
        |       |       |       |       |       |       |       |       |
        |       |       |       |       |       |       |       |       |
       PGHP   PGHP     PGHP    PGHP    PGHP    PGHP    PGHP    UoPG    PGHP
       (A)    (B)      (C)     (D)     (E)     (F)     (G)     (H)     (I)
   

   where the Spatial Index Related Geometry has row_count = 3 and column_count = 3, spacing_units = arc seconds.

   Please note that the components of the Spatial Index Related Geometry are not ordered; the Geometry Spatial Index Data is used to identify the individual tiles.

FAQs

What is the purpose of this class?

This class allows Geometries to be organized (tiled) according to some spatial index.

My data consists of terrain Polygons that are tiled along the lines of a grid, but some Polygons here and there cross over tile boundaries. Can I organize these Polygons with a Spatial Index Related Geometry?

Yes, if its strict_organizing_principle is set to SE_FALSE to indicate that the indexing is not strictly followed (see Spatial Index Related Organizing Principle, example #1). Each tile of the spatial index would be represented by a Geometry Hierarchy component of the Spatial Index Related Geometry.

Where is the origin of the spatial index?

The required Location component of the Spatial Index Related Geometry specifies the origin of the spatial index, which is its lower-left corner.

Constraints

• No Attribute Conflicts
• Non Crossing Aggregations
• Non Cyclic Aggregations
• Precedence of Attribute Set Index
• Non Crossing Associations
• Color Mapping Restrictions
• Image Mapping Functions and Texture Coordinates
• Distinct Link Objects
• Spatial Index Related Organizing Principle

Associated by (one-way)(inherited)

• optionally, a Hierarchy Summary Item
• optionally, some Reference Surfaces

Associated with (two-way)(inherited)

• optionally, some Features
• optionally, some Geometry Hierarchies

Composed of (one-way)(inherited)

• optionally, some {ordered} Attribute Set Indices
• optionally, a Classification Data
• optionally, some Property Tables
• optionally, some Property Table References
• optionally, some Property Values
• optionally, a Reference Surface
• optionally, some Sound Instances
• optionally, a Spatial Domain
• optionally, a Bounding Volume
• optionally, a Center of Buoyancy
• optionally, a Center of Mass
• optionally, a Center of Pressure
• optionally, some Collision Volumes
• optionally, a Conformal Behavior
• optionally, a LSR Transformation
• optionally, an Overload Priority Index
• optionally, some Property Descriptions
• optionally, a Stamp Behavior
• optionally, some {ordered} Colors
• optionally, a Light Rendering Properties
• optionally, a Rendering Properties
• optionally, some {ordered} Image Mapping Functions
• optionally, a Rendering Priority Level

Composed of (one-way)

• one Location (notes)

Composed of (two-way)(inherited)

• optionally, some Hierarchical Tables
• optionally, some Light Sources

Composed of (two-way)

• one or more Geometry Hierarchies through Geometry Spatial Index Data

Composed of (one-way metadata)(inherited)

• optionally, a Time Constraints Data
• optionally, an Access
• optionally, some Browse Graphics
• optionally, some Cross References
• optionally, a Data Quality
• optionally, a Keywords
• optionally, a Point of Contact

Component of (two-way)(inherited)

• optionally, some Alternate Hierarchy Related Geometries through Geometry Hierarchy Data
• optionally, some Animation Related Geometries
• optionally, some Classification Related Geometries through Geometry Classification Data
• optionally, an Environment Root
• optionally, some Geometry Separating Plane Relations through Geometry Separating Plane Data
• optionally, a Geometry Model
• optionally, some Level of Detail Related Geometries through Geometry Level of Detail Data
• optionally, some Oct Tree Related Geometries through Geometry Oct Tree Data
• optionally, some Time Related Geometries through Geometry Time Constraints Data
• optionally, some Perimeter Related Geometries through Geometry Perimeter Data
• optionally, some Quad Tree Related Geometries through Geometry Quad Tree Data
• optionally, some Spatial Index Related Geometries through Geometry Spatial Index Data
• optionally, some State Related Geometries through Geometry State Data
• optionally, some Union of Geometry Hierarchies

Inherited Field Elements

Field Elements

Notes

Composed of Notes

Location

 The origin of the collection.  The lower-left corner.

Fields Notes

unique_descendants

 If SE_TRUE, then for any object that exists 'below' this aggregation,
 each object will appear in only one 'branch' of this aggregation.
 If SE_FALSE, then objects may appear in multiple 'branches' of this
 aggregation.

independent_topologies

 If SE_TRUE, then each 'branch' from this aggregation is its own,
 independent topology.  If SE_FALSE, then all of the branches exist
 within the same topology.

strict_organizing_principle

 If true, then each 'branch' strictly follows the rules of this
 aggregation.  If false, then each 'branch' might bend the rules a bit.
 For example, if this is a spatial aggregation, than 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, then 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.

sparse

 If SE_FALSE, then all column and row entries (all expected Geometry
 Hierarchy components) are present.  If SE_TRUE, one or more entries
 are not present.

column_width

 length of a cell in the given units along the X axis

row_width

 length of a cell in the given units along the Y axis