The Generate Airspace Lines tool can produce AirspaceLine features from Airspace polygon features. These AirspaceLine cartographic features can be used as the basis for charting complex line symbols. The Label Airspaces parameter specifies how these AirspaceLine features are labeled and can be used to achieve specific charting goals.
The charting of AirspaceLine features may require special line symbols to distinguish whether a line is coincident to neighboring Airspace features of certain types or if a line intersects other surrounding airspaces. Similarly, labels or annotations specifying the Airspace features of either side can also be generated.
If the Label Airspaces parameter is checked, the output line features contain information from both intersecting and neighboring Airspace features. If the Label Airspaces parameter is unchecked, the output line features only contain information from neighboring Airspace features.
Label Airspaces parameter checked
When the Label Airspaces parameter is checked, or if the Python keyword is set to INTERSECTING_AIRSPACES, the lines are generated through a process that planarizes the airspace polygons and creates labels with information from intersecting Airspaces. The example below shows five input Airspace features processed using the Generate Airspace Lines tool. The diagrams show how the final AirspaceLine output is produced.
Airspace input
In the following image, five Airspace features of varying DISTVERTLOWER_VAL values are processed with the Label Airspaces parameter checked.
Nota:
The preference used in this example was simplified to only process one Airspace label, DISTVERTLOWER_VAL, which is an attribute in the input Airspace features. The Airspace labels configured in the preference will be used during processing to aggregate these Airspace attribute values and populate the AirspaceLine left and right labels with them.
AirspaceLine intermediate results
While the tool is running, the polygons are planarized into lines so that intersecting line features are split into individual segments at each intersection. Nine intermediate AirspaceLine features are produced. The tool then labels the lines. Labeling is done by intersecting those lines with the original polygons to determine what is left or right of the line depending on the label information provided in the Target Airspace Lines Features parameter's LEFTLABEL_TXT and RIGHTLABEL_TXT fields.
Nota:
The intermediate results are for illustration only and won't directly appear in the AirspaceLine output.
AirspaceLine final results
After labeling, the tool dissolves the intermediate lines by combining lines with common left and right labels. The final seven line features are then copied to the output feature class.
This allows you to form a continuous line with similar intersecting Airspace features, which can only be viewed with AirspaceLine features f and g in the example.
Nota:
The AirspaceLine feature's left and right labels will also contain information from neighboring Airspace features.
Label Airspaces parameter unchecked
When the Label Airspaces parameter is unchecked, or the Python keyword is set to NO_INTERSECTING_AIRSPACES, the lines are labeled differently. The example below shows three input Airspace features processed with the Generate Airspaces Lines tool with the Label Airspaces parameter unchecked.
Airspace input
In the following image, three Airspace features of varying DISTVERTLOWER_VAL values are processed with the Label Airspaces parameter unchecked.
The preference used in this example was simplified to only process one Airspace label, DISTVERTLOWER_VAL, which is an attribute in the input Airspace features. The Airspace labels configured in the preference will be used during processing to aggregate these Airspace attribute values and populate the AirspaceLine left and right labels with them.
AirspaceLine intermediate results
While the tool is running, it planarizes the polygons into seven lines. The tool then labels the lines. The lines do not intersect the Airspace features. Labeling is done by taking each AirspaceLine feature that is coincident with more than one Airspace feature and writing the corresponding Airspace's DISTLOWER_VAL value in the appropriate left label and right label. All other AirspaceLine features that are not coincident with any Airspace features will have their right label populated with the DISTLOWER_VAL value from its originating Airspace feature.
Nota:
The intermediate results are for illustration only and won't directly appear in the AirspaceLine output.
AirspaceLine final results
After labeling, the tool dissolves the intermediate lines by combining lines with common left and right labels. The final four line features are then copied to the output feature class. After the tool has finished, there is only one line , line I, that includes a left label because it was coincident with two Airspace features.
Left labels are only populated when a line shares an edge.