Erlik- yes cinema can embed an environment map (including HDR) into any material as well as having a separate reflection channel, the two of which can be set so having something to reflect other than black will override the env map or not as you choose. I tend to use two sky objects with hdr. The first for reflection/environment with seen by camera but not by the GI engine; the second with a blurred hdr set to not seen by camera by by GI. The hdr can be adjusted individually in each material. Flexibility like this is what makes for serious lighting fun and cool effects.

AS- try a map which will result in a fade from mid grey on one pole of the envirnment sphere to  full white by  2/3 way to the other pole. how you orient the environment sphere will give you some directionality control of your GI.

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