Level Of Detail (LOD) Ranges

Level of detail (LOD) ranges are controlled several properties in FlightGear, with the below default values.

Scenery ranges

Note  The LOD ranges are only set during the scenery loading process. Therefore a scenery reload may be required to change the currently loaded tiles.

Property	Default	Description
sim/rendering/static-lod/detailed	1500 m	All objects (buildings etc) display withing this range. Building meshes using OBJECT_BUILDING_MESH_DETAILED The actual visibility range is randomly distributed from /sim/static-lod/rough to twice /sim/static-lod/rough, to reduce apparent "popping".
/sim/rendering/static-lod/rough	7500 m	Terrain and non terrain objects will be displayed within this range, as follows: Objects listed in scenery STG files using OBJECT_STATIC or OBJECT_SHARED verbs Random scenery objects Random trees Random buildings Building meshes using OBJECT_BUILDING_MESH_ROUGH. The actual visibility range is randomly distributed from /sim/static-lod/rough to twice /sim/static-lod/rough, to reduce apparent "popping".
/sim/rendering/static-lod/bare	21000 m	Only terrain after this point

AI/MP ranges

Note  For a while now FG supports size based LOD - this is the size of the model on screen in pixels and can be configured in the static lod dialog. All models should have an assigned fallback model; this is a low detail model that can be used for models that are further away.

AI/MP models (other models that aren't being flown/operated by the user) have two models. The first of these is the low detail (or fallback) model, which can be defined by an model developer (sim/model/fallback-model-index) as one of the values in $FGData/AI/Aircraft/fallback_models.xml. When there is no fallback model defined for a model the blue-yellow glider will be used.

AI/MP ranges can either bet set as pixels of the object on screen, or distance from the viewer in meters. This is controlled by the /sim/rendering/static-lod/aimp-range-mode-distance property.

Property	Default	Description
/sim/rendering/static-lod/aimp-range-mode-distance	false	Configures the range mode: If set to false the values of /sim/rendering/static-lod/aimp-detailed and /sim/rendering/static-lod/aimp-bare are pixels on the screen. This is default. If set to true, the values are distance from the camera in meters.
/sim/rendering/static-lod/aimp-detailed	400 px	This property works differently depending on the range mode. In pixel mode it is the size (in pixels) of the object on screen. When greater than this amount of pixels the detailed model will be used In range mode it is the distance from the viewpoint, when within this range the detailed model will be used.
/sim/rendering/static-lod/aimp-bare	0 px	This property works differently depending on the range mode. In pixel mode it is the minimum size (in pixels) of the object on screen. If the object is below /sim/rendering/static-lod/aimp-bare pixels in size, it will not be displayed. When the number of pixels is between /sim/rendering/static-lod/aimp-bare and /sim/rendering/static-lod/aimp-detailed, the low detail (fallback) model will be used. In range mode it is the distance beyond the /sim/rendering/static-lod/aimp-detailed value, at which the low detail model will be used. I.e. the low detail model will be used in the range from /sim/rendering/static-lod/aimp-detailed to (/sim/rendering/static-lod/aimp-detailed + /sim/rendering/static-lod/aimp-bare) .
/sim/rendering/static-lod/aimp-interior	200m	Range at which to display the model interior (when the model has a mesh defined as being the interior).

Related content

Wiki articles

• FlightGear configuration via XML. See in particular the section Adding your own settings.

Forum topics

• 3d models, how to produce them in an understandable way topic on the forum (April 2020-) - Touches on the subject of not using LOD range animations in scenery models.

Source code

• gitlab/flightgear/fgdata/next/defaults.xml. Do not change this file, rather follow these instructions.
• gitlab/flightgear/simgear/next/simgear/scene