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The SEDRIS Data Representation Model
APPENDIX A - Classes Proximity Data |
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An instance of this DRM class specifies the semantic meaning of the association relationship with which it is bound. This is a spatial relationship.
Consider an aerodrome providing air traffic control and an air transportation route designed to channel air traffic into that aerodrome. The aerodrome is represented in a transmittal by a <Point Feature> instance A and the air transportation route is represented by a <Linear Feature> instance R. The topology of R consists of a sequence of <Feature Edge> instances E1, E2, E3, and E4 that are associated to R through <Edge Direction> link objects such that
In this transmittal, N0 is associated with A and represents the location of the aerodrome, while N1, N2, N3, and N4 are aviation waypoints associated with <Point Feature> instances W1, W2, W3, and W4. At each waypoint an aircraft pilot may find it useful to know the shortest distance to the aerodrome A, so each Wi has an association relationship to A through a <Proximity Data> link object with meaning = SE_SPATASSMEANTYP_IN_PROXIMITY_OF and distance = the shortest distance from that waypoint to the aerodrome.
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The meaning field specifies the semantic meaning of the association relationship with which the <Base Spatial Association Data> instance is bound.
The value of the distance field, which is measured in metres, represents the shortest distance between any two points of thing1 and thing2, where thing1 and thing2 are the environmental objects represented by the DRM object instances for which a relationship is being represented by the <Proximity Data> instance.
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