Level Of Detail (LOD) Ranges: Difference between revisions

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Level of Detail (LOD) is controlled by three properties in FlightGear, with the following default values:
'''Level of detail''' ('''LOD''') '''ranges''' are controlled several properties in FlightGear, with the below default values.
* /sim/static-lod/detailed=1500
* /sim/static-lod/rough=9000
* /sim/static-lod/bare=30000


Note that you need to re-load scenery for new values to have an effect on STG files.
== 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.}}
{| class="wikitable"
|-
! Property !! Default !! Description
|-
| <code>sim/rendering/static-lod/detailed</code> || 1500 m ||All objects (buildings etc) display withing this range.
* Building meshes using OBJECT_BUILDING_MESH_DETAILED (Additional 1414 m is added as these meshes are 2000 x 2000 m)
* The actual visibility range is randomly distributed from <code>/sim/static-lod/rough</code> to twice <code>/sim/static-lod/rough</code>, to reduce apparent "popping".
|-
| <code>/sim/rendering/static-lod/rough</code> || 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. (Additional 1414 m is added as these meshes are 2000 x 2000 m)


These properties control the distance at which various parts of the scenery become visible.  They are also used by aircraft modellers to control the visibility of different aircraft parts.
The actual visibility range is randomly distributed from <code>/sim/static-lod/rough</code> to twice <code>/sim/static-lod/rough</code>, to reduce apparent "popping".
|-
| <code>/sim/rendering/static-lod/bare</code> || 21000 m || Only terrain after this point
|}


We also have the following settings used for AI models:
== AI/MP ranges ==
* /sim/static-lod/ai-range-mode-pixel=false  - this is used to change the LOD model to use apparent pixel size rather than distance
* /sim/static-lod/ai-detailed=10000
* /sim/static-lod/ai-bare=10000 - currently commented out
* /sim/static-lod/ai-interior=50


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 (<code>sim/model/fallback-model-index</code>) as one of the values in <code>$FGData/AI/Aircraft/fallback_models.xml</code>. When there is no fallback model defined for a model the blue-yellow glider will be used.


There are three properties that control the operation of the LOD ranges for
We also have the following settings used for AI models:
{| class="wikitable"
|-
! Property !! Default !! Description
|-
| <code>/sim/rendering/static-lod/aimp-range-mode-distance</code> || false || When true the distances in the following aimp- properties are considered to be the distance from the camera.
|-
| <code>/sim/rendering/static-lod/aimp-detailed</code> || 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.
|-
| <code>/sim/rendering/static-lod/aimp-bare</code> || 0 px || This property works differently depending on the range mode.
* In pixel mode it is the maximum size (in pixels) of the object on screen. When below this amount the low detail (fallback) model will be used. It is possible to set this to a non-zero value to stop drawing anything when close (although quite why anyone would want to do that is beyond me), and thus a value of 0 is the expected usage of this in pixel mode.
* In range mode it is the distance from the viewpoint, when above this distance the low detail model will be used.
|}


== Model interiors ==
{| class="wikitable"
|-
! Property !! Default !! Description
|-
| <code>/sim/rendering/static-lod/aimp-interior</code> || 200 m || Range at which to display the model interior (when the model has a mesh defined as being the interior).
|}


They are used to control the loading and visibility of scenery elements as follows:
== Related content ==
 
=== Wiki articles ===
== /sim/static-lod/bare ==
* [[FlightGear configuration via XML]].  See in particular the section [[FlightGear configuration via XML#Adding your own settings|Adding your own settings]].
* Scenery tiles
 
== /sim/static-lod/rough ==
* 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.  (Additional 1414m is added as these meshes are 2000mx2000m)
 
The actual visibility range is randomly distributed from /sim/static-lod/rough to twice /sim/static-lod/rough, to reduce apparent "popping".
 
== /sim/static-lod/detailed ==
* Building meshes using OBJECT_BUILDING_MESH_DETAILED (Additional 1414m is added as these meshes are 2000mx2000m)


The actual visibility range is randomly distributed from /sim/static-lod/rough to twice /sim/static-lod/rough, to reduce apparent "popping".
=== Forum topics ===
* {{forum link|t=37353|title=3d models, how to produce them in an understandable way}} (April 2020-) - Touches on the subject of not using LOD range animations in scenery models.


=== Source code ===
* {{fgdata source|path=defaults.xml}}. Do not change this file, rather follow [[FlightGear configuration via XML#Adding your own settings|these instructions]].
* {{simgear source|path=simgear/scene}}


== References ==
[[Category:Rendering]]
{{Appendix}}

Revision as of 11:12, 3 May 2020

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 (Additional 1414 m is added as these meshes are 2000 x 2000 m)
  • 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. (Additional 1414 m is added as these meshes are 2000 x 2000 m)

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

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.

There are three properties that control the operation of the LOD ranges for We also have the following settings used for AI models:

Property Default Description
/sim/rendering/static-lod/aimp-range-mode-distance false When true the distances in the following aimp- properties are considered to be the distance from the camera.
/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 maximum size (in pixels) of the object on screen. When below this amount the low detail (fallback) model will be used. It is possible to set this to a non-zero value to stop drawing anything when close (although quite why anyone would want to do that is beyond me), and thus a value of 0 is the expected usage of this in pixel mode.
  • In range mode it is the distance from the viewpoint, when above this distance the low detail model will be used.

Model interiors

Property Default Description
/sim/rendering/static-lod/aimp-interior 200 m Range at which to display the model interior (when the model has a mesh defined as being the interior).

Related content

Wiki articles

Forum topics

Source code

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