-- world --

scale:

the world scale controls how far the camera is seeing, it also control the size of all the volumetrics domains. The default value is 10000 (10km), it is approximatively the distance of the horizon on a flat land.

-- Sky --

altitude:

the sky altitude controls the height of the point of view in the atmosphere.

0.5 (default)  500  5000  50000 

intensity:

the sky intensity is used to tweak the background global contribution

0.25  1 (default)  2  5 

lighting:

the sky lighting multiplier is used to tweak the light emited by the background but the sky remains untouched.

0  1 (default)  2  5 

reflections:

the sky reflection multiplier controls the glossy contribution of the background.

0.25  1 (default)  2.5  5 

-- Sun --

rotation:

this is the euler rotation of the sun. the X axis represent the elevation and the Z axis the azimuth. the default value of 0,0,0 is pure zenith facing north.

x=45°  x=75°  x=89°  x=89.9° 

z=0°  z=90°  z=180°  z=270° 

show sun :

the show sun option is used to draw or not the sun disc in the sky

sun radius:

this control the size of the sun disc, the default value of 0.009 (radians) means 0.527° which is the mean angular diameter of the sun seen from earth.

0 (or off)  0.009(default)  0.1  0.5 

sun max temperature:

this control the sun maximum temperature at zenith, the sytem automatically adjust the temperature regarding to the elevation but with this you can tweak the final color of the sun at any elevation, also usefull for rendering sci-fi scenes with different stars but the sun.

950  1500  2500 (default)  3500 

sun intensity:

this control how much light is emited from the sun at zenith, a value of 1 (default) fit the sun default luminance and automatically vary with the elevation. this is usefull when you use a dense ground fog or want to tweak the lighting of the scene.

1 (default)  10  100  1000 

-- 2D clouds --

show 2d clouds :

this enable or disble the 2d clouds, these a rendered in the world shader and are faster to render than the 3d clouds, but are less realistics. usefull in combination of 3d clouds to simulate a thin cloud layer or when rendering animations (2D and 3D clouds are animated thanks to the skysim_cloudpos empty in the scene, animate it and the clouds will follow)

density :

this make the 2D clouds more or less denses

1  10 (default)  100  1000 

noise scale :

this control the size of the clouds noise (default 750).

0  10  100  1000 

altitude:

this is the altitude where the clouds starts. it affect the behaviour at horizon.

5  50  500 (default)  5000 

clouds color :

this is used to tweak the clouds color, it is mainly an "artistic" control because 2D clouds are not affected by the sun/sky light (but they contribute to light the scene)

-- Volumetrics clouds --

show volumetrics clouds :

this enable or disable the 3D clouds layers. 3D clouds are much more realistics than 2D clouds as they reacts to the sky/sun light, but are longer to render.

shape:

the shape vector is used to tweak the clouds internal noise (and thus their shapes). The x components stretch the clouds in the x axis, the y component in the y axis and i think you already guessed the z component stretch them in the z axis. It is useful to give the clouds different looks.

1 - 1 - 5  1 - 25 - 10  50 - 50 -50  100 - 100 -100 

noise scale :

the 3D clouds noise scale controls the coverage of the cloud layer.

0.001  0.02 (default)  0.1  1 

altitude:

this is the cloud layer altitude relative to ground.

0.5  50 (default)  500  1500 

depth:

this control the cloud layer depth (in z axis)

5  25  50 (default)  150 

density:

set how dense the clouds are

0.05  5  10 (default)  50 

emission:

set how much light is emitted through the clouds

0  0.01  0.1 (default)  1 

-- Ground --

show ground:

this enable or disable the infinite ground plane. the plane is not really infinite, but it have the right size to match the world scale so it have the illusion of an infinite plane. It comes with a procedural asphalt shader not so nice, feel free to change it to anything (water shaders gives good results on this). just change the material of the skysim_ground object to any one you like.

Altitude:

this just set the altitude of the ground plane (relative to z=0)

-- ground fog --

show ground fog:

this enable or disable the volumetric ground fog. this part enable skysim to produce godrays and dense atmospheres. It comes with a volumetric shader with the right anisotropy for the atmosphere (near 0.75) and gives a real feeling to your renders.

height:

this set the height of the ground fog (relative to ground altitude). The density is automatically adjusted regarding this parameter and can be multiplied with the last control.

0.1 1 (default) 10 100 

density:

this set the density multiplier of the ground fog. This allow to create any type of atmosphere, from dry to wet, sunrise to sunset. The higher this value, the higher must be the sun multiplier to produce nice effects. Godrays need high values.

0.1 1 (default) 10 50 

world margin :

depending of the z position of the camera, the ground fog may not render at horizon, use this parameter to reduce the domain by a percentage. for example, if the world scale is 1000 and this is 10, then the domain will be 1800 units (instead of 2000). This allow to reduce (or increase, but this is a bit a non sense) the ground fog domain, it is usefull to reduce light traveling through the fog and fix the horizon visibility.