|
The SEDRIS Data Representation Model
APPENDIX A - Classes Linear Feature |
|---|
An instance of this DRM class is a <Primitive Feature> with a one-dimensional structure, such as a road, a stream, or a power line.
Consider a <Linear Feature> representing a road.
This <Linear Feature> instance has an ordered set of <Feature Edge> instances defining the 2D or 3D path of its centreline. The <Classification Data> identifies it as a road, while the <Property Value> instances describe the characteristics of the road.
Note that if individual segments of the road had different surface characteristics, they could have been attributed with their own <Property Value> components.
Yes. However, these <Feature Edge> instances shall form an ordered sequence, such that each consecutive pair of <Feature Edge> instances share a common <Feature Node>. Also, any properties of the feature shall remain the same throughout its length. For example, a single road feature (Interstate 95) could conceivably consist of a linear sequence of hundreds or thousands of <Feature Edge> 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.
These components support *attributes for derived objects*; that is, they are used only to specify texture mapping information for geometry that is derived from the <Primitive Feature> by the consumer. These <Image Mapping Function> components shall use <Image Anchor> components to specify the mapping.
This is needed because in many cases, a <Primitive Feature> may be significant only for a particular domain, such as radar.
|