Spherical projection is used for environment textures and IES Light distributions. It performs latitude-longitude mapping for the U and V coordinates. For procedural textures, the W coordinate is the distance from the origin. Figure 1 shows the result of a texture applied to a sphere using spherical mapping.
Figure 1: A texture is mapped a sphere using spherical projection.
When using an image texture to light a scene with the Octane sun and sky node, spherical mapping combined with a transform node allows for the rotation and translation of the texture on the environment sphere. Figure 2 shows a graph of this arrangement.
Figure 2: An image texture is mapped to the texture node input of a SunSky node. Spherical projection is used to map the texture and a Transform 3D node is used to adjust the rotation and position of the texture on the environment.