The SEDRIS Data Representation Model
APPENDIX A - Classes
Spatial Index Related Features

Class Name: Spatial Index Related Features

Superclass - <Aggregate Feature>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance of this DRM class specifies an aggregation of <Feature Hierarchy> objects in which each component <Feature Hierarchy> represents a different tile within a spatially indexed (tiled) organization of <Primitive Feature> objects within a SEDRIS transmittal. The <Spatial Index Data> link object corresponding to each component A CLASS="Feature_Hierarchy"> Feature Hierarchy indicates which tile it represents.

This DRM class exists to allow <Feature> objects to be organized (tiled) according to some regular spatial index.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

This class appears on only one page of the DRM class diagram.

Example

  1. See <<Spatial Index Related Organizing Principle>>, example #2.

FAQs

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

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 #2). Each tile of the spatial index would be represented by a <Feature Hierarchy> component of the <Spatial Index Related Features>.

Where is the origin of the spatial index?

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

Constraints

Associated by (one-way)(inherited)

Associated with (two-way)(inherited)

Composed of (two-way)(inherited)

Composed of (two-way)

Composed of (two-way metadata)(inherited)

Component of (two-way)(inherited)

Inherited Field Elements

SE_Boolean unique_descendants; (notes)
SE_Boolean strict_organizing_principle; (notes)

Field Elements

SE_Boolean sparse; (notes)
SE_Integer_Positive column_count;
SE_Integer_Positive row_count;
SE_Long_Float column_width; (notes)
SE_Long_Float row_width; (notes)
SE_Spatial_Index_Spacing_Unit spacing_unit;

Notes

Associated with Notes


Feature

 An association between two <Feature> instances indicates
 that they are alternate representations of the same
 environmental object.

Geometry_Hierarchy

 An association between a <Geometry Hierarchy> instance and a
 <Feature> instance indicates that the <Geometry Hierarchy>
 and the <Feature> are alternate representations of the same
 environmental object.

Property_Grid

 An association between a <Property Grid> instance and a
 <Feature> instance indicates that the <Feature> and the <Property Grid>
 (or some specific cell data within that <Property Grid>) are
 alternate representations of the same environmental object.
 Each associated <Property Grid> will indicate which is the case.

Composed of Notes


Image_Mapping_Function

 This relationship exists to support "attributes for derived objects."
 That is, these components are used only to specify texture mapping
 information for geometry that is to be derived from the
 <Aggregate Feature> by the consumer. These <Image Mapping Function>
 instances shall use <Image Anchor> components to specify the mapping.

Presentation_Domain

 This is needed for cases in which an <Aggregate Feature> is
 significant only for a particular domain, such as radar.

Location

 This is the origin of the collection, which is the lower-left corner.

Fields Notes


unique_descendants

 If this value is SE_TRUE, each 'descendant' of this aggregation -
 that is, each <Feature> instance that exists in the component tree
 rooted at the given <Aggregate Feature> - 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 <Feature> instance
 appears in more than one 'branch' of the aggregation.

strict_organizing_principle

 If this value 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.

sparse

 If this value is SE_FALSE, all column and row entries are present;
 otherwise one or more entries are not present.

column_width

 This is the length of a cell in the given unit along the X axis.

row_width

 This is the length of a cell in the given unit along the Y axis.
Prev: Spatial Index Related Feature Topology. Next: Spatial Index Related Geometry. Up:Index.

Last updated: May 15, 2003 Copyright © 2003 SEDRIS™