environment
Defines the lighting environment and the skybox of the scene.
Environments are usually captured as high-resolution HDR equirectangular images and processed by the cmgen tool to generate the data needed by IndirectLight.
You can also process an hdr at runtime but this is more consuming.
Currently IndirectLight is intended to be used for "distant probes", that is, to represent global illumination from a distant (i.e. at infinity) environment, such as the sky or distant mountains. Only a single IndirectLight can be used in a Scene. This limitation will be lifted in the future.
When added to a Scene, the Skybox fills all untouched pixels.