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)