The Spherical Panorama Input node is used to load media shot by 360° spherical cameras and stiched into an Equirectangular Panorama.
Further information about the individual components of the Spherical Panorama Input node are available in the Media Management section:
Source: The source media information. This is also where media can be loaded from disk.
Mask: The mask panel where media containing a pre-rendered mask can be loaded from disk.
Spherical Viewer: The spherical panorama viewer.