NAME

       fgelev - Compute FlightGear scenery elevation for a given list of points

SYNOPSIS

       fgelev [--expire num] [--print-solidness] [--fg-root rootdir] [--fg-scenery scenerydir]

DESCRIPTION

       fgelev  is  a standalone utility that, given a list of points on standard input, prints the corresponding
       elevation for each of them on standard output. It  can  also  (optionally)  print  whether  the  material
       covering that point is solid or not.

       The list of points must be in the following form:

           id lon lat

       where  id  is  an  arbitrary  identifier  for the point, lon is the longitude of the point and lat is the
       latitude of the point. Positive longitudes (latitudes)  correspond  to  points  located  in  the  Eastern
       (Northern) hemisphere; negative ones correspond to points located in the Western (Southern) hemisphere.

       The list of elevations returned by fgelev is in the following form:

           id: elev solid

       where id is the identifier of the point passed as input, elev is the elevation of the point in meters (or
       -1000 if the elevation of the given point was not found) and solid is:

       •  the string solid if the parameter --print-solidness was passed to fgelev and the material covering the
          point is solid;

       •  the  string  -  if  the parameter --print-solidness was passed to fgelev and the material covering the
          point is not solid;

       •  absent if the parameter --print-solidness was not passed to fgelev.

OPTIONS

       --expire num
              To speed up elevation data retrieval, fgelev uses an internal cache. This  option  lets  the  user
              specify  the  number  of  requests  after  which, if a point was not queried in them, it should be
              marked as expired. By default, fgelev expires points not queried in the last 10 requests.

       --print-solidness
              Require fgelev to print the solidness  of  the  material  covering  the  queried  point.  See  the
              DESCRIPTION section for more details.

       --fg-root rootdir
              Set  the  FlightGear  data root directory ($FG_ROOT) to rootdir. If this option is not set, fgelev
              uses the path specified in the FG_ROOT environment variable or, absent that, the  FlightGear  data
              directory chosen at the time the program was compiled.

       --fg-scenery scenerydir
              Set  the  FlightGear  scenery  directory  ($FG_SCENERY) to scenerydir.  If this option is not set,
              fgelev uses the path specified in the FG_SCENERY environment variable or, absent that, the Scenery
              subdirectory inside $FG_ROOT.

EXIT STATUS

       fgelev exits with EXIT_SUCCESS on success, with EXIT_FAILURE if it is unable to read data  from  standard
       input or to load the scenery.

ENVIRONMENT

       FG_ROOT
           If FG_ROOT is set and --fg-root is not set, it specifies the root data directory to use.

       FG_SCENERY
           If FG_SCENERY is set and --fg-scenery is not set, it specifies the scenery directory to use.

SEE ALSO

       fgfs(1)

FlightGear                                         2017-06-04                                          FGELEV(1)