Command entry: 
Create a Daylight system.
Choose mr Sky as the sky light.
Choose CIE as the sky model.
mr Sky: CIE Parameters rollout
The CIE sky model is a physically accurate sky model recognized as an industry standard. (CIE stands for Commission Internationale de l’Éclairage: the International Lighting Commission.) It is controlled by two illuminance values, and you can choose either an overcast or a clear sky.
When you render while the CIE sky model is active, the sky color derives from the Haze value in the mr Physical Sky shader. By default this is 0.0 (a clear sky, blue in the daytime), but you can use the shader to change the Haze value.
Interface
- Diffuse Horizontal Illuminance
-
The illuminance of the sky measured by a luminance meter placed horizontally, outdoors, excluding the contribution from the
sun. Default=10000.0 lx.
You can animate this value.
- Direct Normal Illuminance
-
The illuminance of the sun measured by a luminance meter aimed directly at the sun. Default=10000.0 lx.
You can animate this value.
- Overcast Sky
-
(The default.) Specifies an overcast sky.
- Clear Sky
-
NoteIf you have chosen American units as the active lighting units, the illuminance values appear as footcandles (fc) rather than
lux (lx).
