|
The SEDRIS Data Representation Model
APPENDIX A - Classes Feature Representation |
|---|
An instance of a concrete class derived from this DRM class represents an entity in the environment (or a hierarchical collection of such entities) so as to abstract away all spatial information that is not needed to reason about that entity in terms of its spatial connectivity
A wide variety of spatially located entities, including roads, railroads, streams, rivers, lakes, bridges, buildings, built-up areas, forests, fields, political boundaries, powerlines, airfields, and so on can be abstractly represented as <Feature Representation> instances. <Feature Representation> instances may be organized into thematic layers, each forming a separate topological surface.
No. <Feature Representation> instances 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 of the United States 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 Feature> instances.
An association between two <Feature Representation> 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 between a <Geometry Hierarchy> instance and a <Feature Representation> 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 a <Property Grid> instance and a <Feature Representation> instance indicates that the environmental object(s) represented by the <Feature Representation> instance and the <Property Grid> instance (or some specific cell data within that <Property Grid> instance) have the semantic relationship indicated by the <Base Association Data> instance on the association relationship. Each associated <Property Grid> instance will indicate whether the entire <Property Grid> instance or only some specific cell data within it is participating in the relationship in question.
An association between two <Feature Representation> 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 between a <Geometry Hierarchy> instance and a <Feature Representation> 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 a <Property Grid> instance and a <Feature Representation> instance indicates that the environmental object(s) represented by the <Feature Representation> instance and the <Property Grid> instance (or some specific cell data within that <Property Grid> instance) have the semantic relationship indicated by the <Base Association Data> instance on the association relationship. Each associated <Property Grid> instance will indicate whether the entire <Property Grid> instance or only some specific cell data within it is participating in the relationship in question.
|