The SEDRIS Data Representation Model
APPENDIX B - Constraints
Volume Shell Face Consistency

Definition

The following restrictions apply:

  1. A <Feature Face> instance shall appear no more than twice in a <Feature Volume Shell> instance, once through a <Face Direction> link object with front set to SE_TRUE and once through a <Face Direction> link object with front set to SE_FALSE.

Rationale

Since a <Feature Face> instance has exactly two sides, it can associated with at most two <Feature Volume Shell> instances, and can appear at most twice in the collection of <Feature Face> instances associated with a single <Feature Volume Shell> instance.

Example

  1. A <Feature Volume> instance V1 representing a cube is bounded by six <Feature Face> instances F1 through F6. F1, F2, F3, F4, F5, and F6 are all associated to V1. F1, F2, F3, F4, F5, and F6 each appear once in the collection of <Feature Face> instances associated with the exterior <Feature Volume Shell> component of V1.

FAQs

Can a <Feature Face> instance be associated with a <Feature Volume Shell> instance more than once?

Yes. A "dangling" <Feature Face> instance that projects into the interior of a <Feature Volume> instance is included in the external shell of that <Feature Volume> instance two times, once for each side of the <Feature Face> instance.

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Last updated: July 26, 2006 Copyright © 2006 SEDRIS™