Quote - The link is interesting but it depends on using the BaginsBill environment prop which is something I never figured out and I am not sure that it applies to interior scenes which are about 95% of my render scenes.

I guess it states that AO should not be used with IDL but I am still not sure about IBL and IDL.

The EnvSphere is really easy to use, nothing complicated about it. You load it, load an equirectangular image on it and you're done :)
It's first use (pre P8) was to simulate an entire environment with a pic that surrounds all your scene, but now with P8 and IDL it participates in the global lighting and illumination.

AO should not be used with IDL indeed.

And i could have done the exact same render with an IBL and IDL instead of the EnvSphere, though i would have lost the sky, and i should have added it in post. The EnvSphere avoids that extra step.
Bagginsbill said in other threads that IBL, when used with IDL, does the same thing as the EnvSphere. The IBL will project the probe image on a virtual sphere (with virtual, understand that it is not present in the scene) that will acts exactly like the EnvSphere by using this image in the illumination.
Bill shortened this idea by saying that if you want to use a light probe image for the illumination, use IBL, if you want to use an equirectangular image for the illumination, use the EnvSphere.

For an interior scene, the EnvSphere has no utility, nor has an IBL. Except if the room that surrounds your character has any opening (a window, an opened door etc).
Of course you could still use them (EnvSphere or IBL) to 'fake' a room for instance. Though the IDL will have no walls for the light to bounces off.

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