|
The SEDRIS Data Representation Model
APPENDIX A - Classes Connected Feature Edge |
|---|
An instance of this DRM class specifies the one-way topological relationship between a <Feature Node> and the ordered collection of <Feature Edge> instances that are connected to it within a given topological surface, that is, which have the <Feature Node> instance as an endpoint and lie in a common topological surface.
If a <Feature Node> instance is the endpoint
of a <Feature Edge> instance, it is required
to have a <Connected Feature Edge>
component which associates to that
At feature topology levels 0 through 3, all of the <Feature Edge> instances connected to a <Feature Node> lie in the same topological surface, so that they shall be ordered around the <Feature Node> via a single <Connected Feature Edge> instance.
At feature topology level 4, <Feature Edge> instances can connect to <Feature Node> from any direction in 3-dimensional space, such that the <Feature Edge> instances may be located in different topological surfaces. In this case, the <Feature Edge> instances shall be organized into subsets, one for each separate topological surface, so that the <Feature Node> instance has a separate <Connected Feature Edge> component for each such subset.
A <Feature Node> that represents a four-way road intersection has a <Connected Feature Edge> component, which is associated with each of the four <Feature Edge> instances that represent the road segments that meet at the intersection. Conversely, each of those four <Feature Edge> instances is associated to the <Feature Edge>, as either its starting or ending node.
Yes. If a <Feature Edge> instance forms a loop, so that both of its ordered <Feature Node> associates are the same <Feature Node> instance, then that <Feature Edge> will appear exactly twice in the collection of <Feature Edge> instances associated with the <Connected Feature Edge>.
|