Abstract Class Name: Feature

Superclass - SEDRIS Abstract Base

Subclasses

• Feature Hierarchy
• Primitive Feature

Definition

An abstract representation of a real-world geographic entity or a hierarchical collection of such geographic entities.

Primary Page in DRM Diagram:

• 8

Secondary Pages in DRM Diagram:

• 3
• 10
• 14

Example

1. A wide variety of spatially located entities, including roads, railroads, streams, rivers, lakes, bridges, buildings, built-up areas, forests, fields, political boundaries, powerlines, airfields, etc. can be abstractly represented as Features. Features may be organized into thematic layers, each forming a separate topological surface.

FAQs

Are there any limits on the size of a feature?

No. Features are conceptual entities. There are no limits on the size of a single feature, and very few limits on what can be considered to be a single feature. For example, the entire Interstate highway system could be considered to be a single high-level feature, if that were useful in a particular context. However, there are some limits on individual Primitive Features.

Constraints

• Image Mapping Functions and Texture Coordinates
• No Attribute Conflicts
• Non Crossing Aggregations
• Non Crossing Associations
• Precedence of Attribute Set Index

Associated with (two-way)

• optionally, some Features
• optionally, some Geometry Hierarchies
• optionally, some Property Grids

Composed of (one-way)

• optionally, some {ordered} Attribute Set Indices
• optionally, a Classification Data
• optionally, some Colors
• optionally, some {ordered} Image Mapping Functions (notes)
• optionally, some Labels
• optionally, some Property Tables
• optionally, some Property Table References
• optionally, some Property Values
• optionally, a Rendering Priority Level
• optionally, a Spatial Domain

Composed of (one-way metadata)

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

Component of (two-way)

• optionally, some Union of Features

Notes

Composed of Notes

Image_Mapping_Function

 Added to support "attributes for derived objects."
 That is, these components are used only to specify
 texture mapping information for geometry that
 is derived from the <Feature> by the consumer.
 These <Image Mapping Functions> must use
 <Image Anchor> components to specify the mapping.