Connected Geometry Edge

The SEDRIS Data Representation Model APPENDIX A - Classes Connected Geometry Edge

Class Name: Connected Geometry Edge

This DRM class is concrete and has no subclasses.

An instance of this DRM class specifies a topological relationship between a <Geometry Node> and an ordered set of <Geometry Edge> instances, indicating that the <Geometry Node> connects the <Geometry Edge> instances.

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

Consider a <Geometry Edge> representing part of the boundary of a <Geometry Face>, which in turn represents a lake. The endpoints of the edge are provided by its associated <Geometry Node> instances.

In order to supply clean, high-level topological information, the data provider gives each of these <Geometry Node> instances a <Connected Geometry Edge> component, which relates it back to each <Geometry Edge> of which it is a part. This allows a consumer, encountering one of the <Geometry Node> instances, to determine what edges it participates in.

When is a <Connected Geometry Edge> instance required?: See <<Connected Edge Restrictions>> for the constraint in question.
Why would a <Geometry Node> have more than one <Connected Geometry Edge> component?: At geometry topology levels 0 through 3, all of the <Geometry Edge> instances connected to a <Geometry Node> are located in the same topological surface; consequently, they can be ordered around the <Geometry Node>. However, at geometry topology level 4, <Geometry Edge> instances can connect to a <Geometry Node> from any direction in 3-dimensional space. When the <Geometry Edge> instances connected to a <Geometry Node> are not all located in the same topological surface, the <Geometry Edge> instances shall be organized into subsets, one for each separate topological surface, and the <Geometry Node> shall have a separate <Connected Geometry Edge> component for each such subset.
Can the same <Geometry Edge> appear more than once in the collection of <Geometry Edge> instances associated with a <Connected Geometry Edge>?: Yes. If a <Geometry Edge> forms a loop, so that its starting and ending <Geometry Node> instances are the same object, that <Geometry Edge> will appear exactly twice in the collection of <Geometry Edge> instances associated with the <Connected Geometry Edge>.

This class has no inherited field elements.

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Last updated: May 15, 2003