AI Traffic: Difference between revisions

The next major aspect of the AI traffic system contains taxiway information. Although the physical layout of each airport is contained in FlightGear's airport database, this information is not sufficient to provide taxiway information. Therefore AI aircraft pickup this type of routing information from an xml file inside the data/AI/Airports directory/. Currently, this information is provided on a one file per airport basis, that can be found in a file called data/AI/Airports/[ICAO]/parking.xml, where ICAO stands for the 4 letter ICAO code for the airport in question.  

For example, see the ground network for EHAM, which is found in <tt>data/Airports/AI/EHAM/parking.xml</tt>. See the end of this page for a small  

excerpt from this file. It should be noted that current development work is planned that aims to move these files from the base package to the scenery repository, so that ground network information and the physical layout of the airport can be updated in parallel. Once this is done, the new location / name for the file will be [fg-scenery]/Airports/[ICAO1]/[ICAO2]/[ICA03]/[ICAO].groundnet.xml. Here [ICAO] stands for the 4 letter ICAO code of the airport in question, and [ICAO1], [ICAO2], and [ICAO3] for the first to third letter of this code.  

'''NOTE:''' Taxidraw versions with a build date of Feb. 5, or later, 2009 support the new naming convention. To make use of this new functionality, make sure to set the FlightGear scenery directory in TaxiDraw (tab 4 in the preferences menu). The directory specified here should be the top level directory, i.e. the one that contains the "Airports", "Objects", and "Terrain" subdirectory. Note that support for this naming convention was introduced somewhat earlier, but versions of TaxiDraw before Feb 5 contain a potentially fatal bug that might ruin your work.

 

In addition, FlightGear cvs of approximately the same date also has support for reading the ground networks from the scenery directory. This feature is not enabled by default. To enable, make sure the property /sim/traffic-manager/use-custom-scenery-data is set to true. This can be done by editing preferences.xml or specifying this property on the command line.  

A ground network file consists of 4 major sections. The first section is optional, although recent versions of TaxiDraw add this section automatically. This section contains a list of all the radio frequencies for the airport in question. FlightGear currently (as of 1.9.0) uses these frequencies to display some ATC messages. As of FlightGear 1.9.0, only startup approval requests are implemented. You can "hear" these by tuning to the first ground frequency listed in the frequencies section.  

 

The second section of the file contains the parameters of the airport's parking  

locations. The third section contains a list of all the nodes in the ground  

network, and the fourth and final section contains a list of segments, or "arcs" as David  

Luff called them initially, which basically describe which node is connected  

to which other node.  

Having finished the technical description of the parking file format, the  

good news is that one probably doesn't need to know too much about the technical  

side of the file structure to create a ground network. Advanced editing capabilities are currently available in TaxiDraw, a separately available utility for airport layout, and ground network editing. The current document describes the functionality of the NEW_GUI_CODE version of TaxiDraw.

Although currently no officially released version of [[TaxiDraw]] (http://TaxiDraw.sourceforge.net/) exists with the ground editing capability, the current CVS version is capable of doing so. Network editing capabilities in TaxiDraw are currently about as stable as the other editing features, however, the ground network module is still somewhat separate from the rest of the airport project code, and ground networks will 'not' automatically be saved together with the airport project. Therefore, do regular exports while editing, to prevent loss of work.

 

 

[[Ubuntu]] or [[Debian]] users may look at the [[Ubuntu fg tools]] page to have TaxiDraw installed in a easy way.

Windows users can also do this either by using the free winCVS program or

using the free cygwin environment. Another possibility is to look on [ftp://ftp.ihg.uni-duisburg.de/FlightGear/Win32]- here you can find the last build of Taxidraw.

== Copying the ground network into FlightGear's data directory ==

Finally, once you have finished creating a groundnet work you can test it in FlightGear. Create a directory in FlightGear's <tt>data/Airports/AI</tt> directory, with the name of the ICAO code of your airport. For example <tt>[[$FG ROOT]]/Airports/AI/EHAM</tt>. Next. locate the file [filename]-groundnetwork.xml and copy this to the directory you just created. Finally, rename the file you just copied to "parking.xml".