FlightGear: Displaying city/airport names (Linux/Unix)

sample image

This feature is implemented as an external Perl program. It's called »signs« and can be used in place of »fgfs«, for example:
$ signs --aircraft=ufo --airport=KCCR

It generates textures »on the fly« and caches them in $FG_ROOT/Local/signs/cache/. There's no change to FlightGear necessary, other than writing into $FG_ROOT. (FlightGear can only load textures from there, but you can replace Local/ with a link to another place, or you can ask the admin to fill the cache for you -- see the -c option). The -h option lists all the possibilities. I started to make the script work under MICROS~1 Windows®, but have no way to test it. Hints and reports welcome! The signs can be turned on/off via dialog (Shift-c).
Requirements: fgfs (> 0.9.8a), perl, gunzip, convert

program and infrastructure [6 kB] REQUIRED (untar in $FG_ROOT)
worldwide airport data, SFO bay bridges   [465 kB] RECOMMENDED (untar in $FG_ROOT)
Austria (cities/villages/objects) [20 kB] OPTIONAL (copy to $FG_ROOT/Local/signs/data/)
Belgium (cities/villages) [34 kB] OPTIONAL (copy to $FG_ROOT/Local/signs/data/)
Germany (cities/villages) [176 kB] OPTIONAL (copy to $FG_ROOT/Local/signs/data/)
Switzerland (cities/villages) [23 kB] OPTIONAL (copy to $FG_ROOT/Local/signs/data/)

Austrian, German, Swiss and Belgian data are from OpenGeoDB, enhanced with elevation data from the FlightGear scenery and additional locations. The elevation data were filled in by another Perl program getelev. It takes the path to one of the data files as input, and generates output on the console and into a file (*.out).