Class Name: Face Direction

Superclass - <SEDRIS Abstract Base>

Subclasses

Definition

An instance of this DRM class indicates which side (the front or the back) of the given <Feature Face> is associated with the given <Areal Feature> instance.

Primary Page in DRM Diagram:

• 8

Secondary Pages in DRM Diagram:

• 23

Example

1. Consider an <Areal Feature> instance representing a grass-covered region, consisting of a single <Regular Feature Face>. The <Face Direction> link data on the relationship between them would be set to SE_TRUE, indicating that the front (i.e., the top) side of the face corresponds to the <Areal Feature>.

FAQs

What if both sides of a <Feature Face> are associated with the same <Areal Feature>?

In such a case the <Feature Face> would appear twice in the collection of <Feature Face> components of the <Areal Feature>, once with the <Face Direction> set to SE_TRUE (front), and once with the <Face Direction> set to SE_FALSE (back).

What if the two sides of a <Feature Face> are associated with different <Areal Feature> instances?

In such a case the <Feature Face> would appear once in the collection of <Feature Face> components of each of the two <Areal Features>. For the <Areal Feature> corresponding to the front side of the face, the <Face Direction> would be set to SE_TRUE, while for the <Areal Feature> corresponding to the back side of the <Feature Face>, the <Face Direction> would be set to SE_FALSE.

How does <Face Direction> relate to the feature topology level?

At feature topology levels 0 through 3, <Face Direction> shall always be SE_TRUE (front). Only at feature topology level 4 can the back side of a <Feature Face> be associated with an <Areal Feature>.

Constraints

• <<Face Direction Levels 0 3>>

Inherited Field Elements

Field Elements