Coding Examples
Example 1-1: R-4912 Sand Springs, NV
This example shows the encoding of the geometry of a Restricted area (R-4912), using the AIXM airspace aggregation concept.
The airspace aggregation is made of four airspace components, which are used in a combination of referencing and copying.
The first AirspaceGeometryComponent used in this aggregation is the 'BASE', from which three other airspace geometry components are subtracted.
The 'BASE' is defined with theAirspaceVolume defining an upperLimit, a lowerlimit and a Surface that has the shape of a rectangular (in the figure below highlighted in orange, "BASE1").
The second AirspaceGeometryComponent is used for a 'SUBTR' operation applied on the 'BASE' component ("SUBTR2").
For this subtract operation the referencing concept is applied, i.e the AirspaceVolumeDependency class has to be defined. According to this concept, the contributorAirspace ("Airspace3") may not have its own defined Surface that is part of the Airspace definition of 'R4912', but is just referenced using theAirspace property. Airspace3 is actually the airspace 'R-4804A Twin Peaks, NV', which has its own defined geometry components.
The dependency is coded as 'HORZ_PROJECTION'. That means that the subtraction is limited to the horizontal projection. Hence, the vertical limits of 'R-4804A' are not taken in into account. The AirspaceGeometryComponent "SUBTR2" has its own defined upperLimit and lowerLimit, which equals the vertical limits defined for "BASE1".
This subtract operation of "SUBTR2" results in a corresponding shape (in the figure below highlighted in orange).
The third AirspaceGeometryComponent is again a 'SUBTR' operation applied on the 'BASE' component ("SUBTR3").
Again, the referencing method is applied utilising the AirspaceVolumeDependency class and its properties defining a horizontal projection dependency only.
After the subtract operation of "SUBTR3", the resulting shape is as highlighted in orange in the figure below.
Again, the vertical limits of the referenced airspace ("Airspace2"), i.e. 'R-4810 DESERT MOUNTAINS, NV', are not taken into account, but the ones defined for airspace component "SUBTR3".
Note that the upper limit of 'R-4810' is lower than the one of airspace component "SUBTR3".
Finally, the fourth AirspaceGeometryComponent is again a 'SUBTR' operation applied on the 'BASE' component ("SUBTR4").
But in this case the referencing method i.e. AirspaceVolumeDependency class is not used.
The vertical limits and the Surface of "SUBTR4" are defined as integral part within the Airspace definition of 'R4912'. (This may be the copy of another airspace.)
Example 1-2: R-4804A Twin Peaks, NV
The airspace used in the previous example in the "SUBTR2" operation, 'R-4804A Twin Peaks, NV', itself is made of an airspace aggregation.
Note that, if the horizontalProjection of of 'R-4804A Twin Peaks, NV' is changed, also the horizontal shape of 'R-4912 Sand Springs, NV' is affected.
R-4804A Twin Peaks, NV' is made of three airspace geometry components, a BASE, a UNION and a SUBTR.
The BASE is defined with vertical limits and a surface that has a shape of a circle by centre point.
The UNION component is also defined by its own vertical limits and surface, that has a shape of a circle by centre point.
Also the SUBTR component is defined by its own vertical limits and surface.
