SixDOF Terrain File Definition

A SixDOF terrain file defines one or more regions, with each region containing one or more locations. The purpose of the file is to define the altitude of terrain measured in feet above sea level. Its primary use is to define airport regions to support SixDOF ground operations.

The file format is as follows:

terrain

  region

    location
      lat       21.3178275
      lon       -157.92026310
      alt_ft    13.0
      minLat    21.27
      maxLat    21.37
      minLon    -157.97
      maxLon    -157.87
    end_location

    ...

    location
      lat       21.4814475
      lon       -158.0378379
      alt_ft    843.0
    end_location

  end_region

end_terrain

There are two configurations for location blocks (as shown above).

The first location shows the fully defined approach, which defines the lat/lon (in degrees) and altitude (in feet) along with minimum/maximum lat lon values. This defines a location that is bounded by the max/min lat/lon. It is assumed that all terrain within that location is at the altitude specified.

The second location shows the partially defined approach, which defines only the lat/lon (in degrees) and altitude (in feet). In this case, the minimum/maximum lat lon values will be calculated, by adjusting values to be approximately 3 nautical miles (3 arc minutes) on either side of the specified lat/lon. It is assumed that all terrain within that location is at the altitude specified.

This allows various airports to be defined within a region and allows several regions to be defined as well. Grouping airports into several regions (rather than simply using a single region) can improve runtime performance.

Return to six_dof_object_types or SixDOF Environment Support