The software uses a few basic rules (version-specific, see above) to determine which data to use to
construct the terrain as a series of concentric rings extending from the aircraft to the horizon, with
less terrain detail rendered as you move toward the horizon.
* LOD determines the radius of the mesh actually displayed under the aircraft.
(e.g. LOD12 mesh has a radius of only about 7 nm, LOD10 mesh extends 30-40nm)
* Beyond this radius, the "priority" of the mesh used under the aircraft drops to 0, and the rules
are applied to determine which mesh data is used to render the terrain for the next concentric ring of mesh.
The radius of that ring will be determined by the LOD of the mesh available for that region.
* This process is repeated until the horizon is reached.
The sim may always use the lowest (default) LOD world mesh at the horizon, or do something entirely different in FS2004,
where distant mountain profiles seem to behave strangely.
Mesh constructed with an LOD of 12 or higher is not used at all with the default fs2002.cfg/fs9.cfg settings.
In FS2004, mesh constructed with an LOD of 10 or higher is rendered exactly the same. An LOD greater than 10 (38.2m)
only increases the file size and reduces the radius where the mesh is rendered.
The above factors determine the maximum possible amount of detail rendered by the sim. Settings in the sim allow
users to reduce the actual amount of detail, usually to improve performance elsewhere.
Terrain Mesh Complexity Slider (controls the value of TERRAIN_ERROR_FACTOR)
In FS2004, TERRAIN_MIN_DEM_AREA and TERRAIN_MAX_DEM_AREA affect the range where the Slider is effective
TERRAIN_MAX_VERTEX_LEVEL, in the [MAIN] section of the cfg file.