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The SEDRIS Data Representation Model
APPENDIX A - Classes Feature Volume Shell |
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An instance of this DRM class specifies the one-directional topological relationship from a <Feature Volume> to the collection of two or more <Feature Face> instances that define one of its boundaries (external or internal).
Consider a <Volumetric Feature> representing a building. It has an associated <Feature Volume>, which defines its extent, shape, and topological relationships; a <Classification Data> component that classifies it as an ECC_BUILDING; <Property Value> components that describe its characteristics, such as material composition, and a <Label> that identifies it as "The Empire State Building". The external boundary of the <Feature Volume> would consist of a single <Feature Volume Shell>, which would be associated with the <Feature Face> instances representing the walls, roof, and (basement) floor of the building.
All <Feature Volume> instances except the instance representing the universal volume are required to have at least one <Feature Volume Shell> component, representing its external boundary. All <Feature Volume> instances, including the instance representing the universal volume, may also have any number of <Feature Volume Shell> components that define internal boundaries (that is, "holes") within the <Feature Volume>.
Yes. A <Feature Face> can appear up to twice in a <Feature Volume Shell>, once with each orientation.
| SE_Boolean | universal; | (notes) |
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The universal field specifies that the given <Feature Volume> instance is the universal <Feature Volume> instance. Within a 3D tile that has feature topology level 5, the universal <Feature Volume> instance lies "outside" any other volumes. Since the external boundary of the universal <Feature Volume> instance is at infinity, a <Feature Volume> instance that has this field set to SE_TRUE has no external <Feature Volume Shell> instance.
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