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The SEDRIS Data Representation Model
APPENDIX A - Classes Feature Model Instance |
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An instance of this DRM case specifies a single case of the existence of a <Feature Model> within a given transmittal, including variations or specialization unique to that case.
Consider a <Model> of a forested area, consisting of a <Geometry Model> describing its renderable geometry, and a <Feature Model> describing it in terms of a collection of <Areal Features>. The <Geometry Model>'s <Geometry Hierarchy> and the <Feature Model>'s component <Union Of Features> are connected by an association relationship, to indicate that they are alternate representations of the same entity.
Wherever the <Model> is to be instanced, a <Feature Model Instance> instance will be placed, with the appropriate <Transformation> to locate it in space and any <Expressions> required for <Variables> within the <Feature Model>.
See Part 4, Volume 4 Topology Technical Guide of the SEDRIS Documentation Set for further information.
An association between two <Feature> instances indicates that they are alternate representations of the same environmental object.
An association between a <Geometry Hierarchy> instance and a <Feature> instance indicates that the <Geometry Hierarchy> and the <Feature> are alternate representations of the same environmental object.
An association between a <Property Grid> instance and a <Feature> instance indicates that the <Feature> and the <Property Grid> (or some specific cell data within that <Property Grid>) are alternate representations of the same environmental object. Each associated <Property Grid> will indicate which is the case.
This positions and orients the <Feature Model Instance> in the target spatial reference frame.
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