@sergo will hopefully correct me if I’m wrong:
When the user interface was built by us and is provided by the appleseed-max plugin (it’s the case for the
appleseed Sky map), then exposure is called exposure.
Now, it turns out that the
appleseed Sky doesn’t have any exposure control. I think it would make sense to add it.
When you see a parameter called “Something Multiplier”, it’s just a linear multiplier (while exposure is exponential). That’s the case of
appleseed Sky's Luminance Multiplier: if set to e.g. 2, then sky’s luminance is multiplied by 2.