This environment type is a flexible Nishita Sky model. It is most useful when rendering scenes as they are seen from outer space. For its effects to be visible, the camera has to have a very high altitude as it moves out into outer space to view the expansive horizon of the planetary body. It takes into account the conditions within and beyond the atmosphere of a planetary body (e.g. planet earth) and its surroundings in space. Instead of a single ground color and a sky/sunset color, there is a planetary surface that reflects and emits light. Most importantly, this node serves to extend the environment's medium (volume rendering and subsurface scattering) with an atmospheric scattering through the planetary body's atmosphere. Here, the atmosphere is perceived as a layer of gas surrounding a planetary mass and it is held in place because of gravity so as the light travels into atmosphere either from the outer layer to the ground or from a light source within the atmosphere, then the atmosphere's density is sampled along the ray at regular intervals resulting in an amount of scattering based on the atmosphere's density. This atmospheric scattering is based on the Nishita Sky Model, a physically based model which displays the variations of color which are optical effects caused by the particles in the atmosphere.
This environment is not connected to the camera and this allows you to zoom the camera view of the objects in the scene in and out while not affecting the position of the environment in the scene. It is a physically based model so it gathers optical depth (transmittance) from the sun position, if the sun position is greater than 0.0f on y axis (upward direction), then it will be colored. If you put it below horizon (i.e. sun position less than 0.0f on the Y axis) then it won't gather transmittance so it will be invisible.
Figure 1: Image rendered using the Planetary Environment where the camera is set at a very high altitude
Altitude
The camera's altitude. This should be set to a very high value in order to view the expansive horizon of the planetary body.
Star Field
Texture to convey star fields behind the planet.
Ground Albedo
surface texture map on the planet.
Ground Reflection
SpecularAmount of specular reflection, or the mirror-like reflection of light photons at the same angle. Used for transparent materials such as glass and water. texture map on the planet.
Ground Glossiness
The planetary glossiness.
Ground Emission
surface texture map on the planet at nighttime.
Ground Normal Map
Normal map on the planet.
Ground Elevation
Elevation map on the planet.
Planetary Axis
The rotational axis of the planet running through the North and South Poles.
Planetary Angle
The rotation around the planetary axis, this has a default value of -1.041.
Figure 2: Image rendered using the Planetary Environment with a star field.
Figure 2: Image rendered using the Planetary Environment with a star field.