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ALS technical notes (view source)

Revision as of 17:00, 28 November 2015

456 bytes added ,  28 November 2015
→‎Quality level mapping: Cleanup
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== Quality level mapping ==
== Quality level mapping ==
The rendering quality of ALS effects is controlled by two main sliders, the landmass effects and transition effects. The transition effects slider regulates the quality of overlaid textured, while the landmass effects slider regulates all other aspects of procedural texturing, such as pixel color post-processing (dust, snow or wet terrain effects) and apparent terrain roughness (bump and parallax mapping).


The rendering quality of ALS effects is controlled by two main sliders, landmass effects and transition effects. Transition effects regulate overlay  texturing quality whereas landmass effects regulate all other aspects of procedural texturing like pixel color postprocessing (dust, snow or wet terrain effects) and apparent terrain roughness (bump and parallax mapping).
In addition, specific effects for certain terrain types (water, urban, forest, agriculture, etc.) and models in the scene can be switched on separately. In some cases, this may be needed for a consistent visual impression. For example, if a dust effect is used on the terrain, the water needs to be rendered using a separate water shader, otherwise it will appear dusty as well. Likewise, if the Rayleigh haze is used in the highest quality terrain effect, then the highest quality water effect needs to be used to see the same Rayleigh scattering effect on the water.


In addition, specific effects for certain terrain types (water, urban, forest, agriculture...) and models in the scene can be switched on separately. In some cases this may be needed for a consistent visual impression: If a dust effect is used on the terrain, water needs to be rendered using a separate water shader, otherwise it will appear dusty as well. Likewise, if the Rayleigh haze is used in the highest quality terrain effect, then the highest quality water effect needs to be used to see the same Rayleigh scattering effect on the water.
For technical reasons (landmass and transition control the same shader code) the settings are sometimes mutually dependent, e.g., if the transition quality is set to level 6, it won't have any effect until the landmass quality is also set to level 6.
 
For technical reasons (landmass and transition control the same shader code) the settings are sometimes mutually dependent, i.e. transition quality level 6 won't have any effect unless landmass quality is also level 6.


=== Transition ===
=== Transition ===
The mapping of quality to visuals of the transition slider is as follows:


The mapping of quality to visuals of the transition slider is
{| class="wikitable"
 
! Level !! Comments
1:
|-
* Base texture scheme
! scope="row" | 1
2:
| Base texture scheme
* Alternative hires airport keep effect
|-
3:
! scope="row" | 2
* Base and overlay texture, runway effect (if landmass > 4)
| Alternative hires airport keep effect
* Supports secondary lights on runway and airport keep
|-
4:
! scope="row" | 3
* Base, overlay and hires texture
|
6:
* Base and overlay texture, runway effect (if landmass is above level 4)
* Base, overlay, hires, detail, grain, dot and rock texture (if landmass > 6)
* Secondary lights on runway and airport keep
|-
! scope="row" | 4
| Base, overlay and hires texture
|-
! scope="row" | 5
| Base, overlay, hires, detail, grain, dot and rock texture (if landmass is level 6)
|}


=== Landmass ===
=== Landmass ===
{{Note|Quality levels 1 and 2 are reserved to represent fixed pipeline rendering and the "default renderer" in an eventually merged rendering GUI. However, ALS is currently switched on per checkbox and not by quality level, and so they do not have a function.}}


(Quality levels 1 and 2 are reserved to represent fixed pipeline rendering and the classic FG default renderer in an eventually merged rendering GUI, currently however ALS is switched on per checkbox and not by quality level, so they do not have a function).
{| class="wikitable"
 
! Level !! Comments
3:
|-
* ALS-rendered position-differential haze and light, moonlight
! scope="row" | 1
 
| ''See note above''
4:
|-
* Procedural snow cover on terrain  
! scope="row" | 2
| ''See note above''
|-
! scope="row" | 3
| ALS-rendered position-differential haze and light, moonlight
|-
! scope="row" | 4
|
* Procedural snow cover on terrain
* Procedural dust and vegetation effects
* Procedural dust and vegetation effects
* Wet terrain effect with approximate reflection half vector
* Wet terrain effect with approximate reflection half vector
* Patchy fog distribution
* Patchy fog distribution
 
|-
5:
! scope="row" | 5
* Noise bump-mapping and parallax mapping of terrain
| Noise bump-mapping and parallax mapping of terrain
 
|-
6: (requires transition 6 as well)
! scope="row" | 6
| (''Requires transition effect level 6'')
* Wet terrain effect with correct reflection half vector
* Wet terrain effect with correct reflection half vector
* Hires bump mapping and snow patchiness
* Hires bump mapping and snow patchiness
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* Secondary lights on all terrain types
* Secondary lights on all terrain types
* Slope line and strata effects
* Slope line and strata effects
|}


== ALS secondary lights ==
== ALS secondary lights ==
Retrieved from "https://wiki.flightgear.org/Special:MobileDiff/90226"

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