Exposure locked only to rendered geometry - possible ?

[SSmolak]

Is there way to lock exposure only to rendered geometry ? I mean that Camera exposure and highlight compensation or even ACES color management treat whole image as one part, included background Sky or HDR map. Highlight compensation looks for brightness part of whole image included very bright sunlight. Is there way to lock Octane exposure to only geometry so it will not include overexposured sky ? In most situations background sky is replaced in post processing but after that rendered geometry is not equalised in RGB tonal range 0-255. I know that the best is to make it rendered to EXR as linear and do it in post but sometimes I need fast preview rendering that mimic this post proccess. Using filmic Ocio we have tonemapped whole image including sky that is not neccessary.

[bepeg4d]

What about using the Visible Environment node to adjust the sky?

ciao,
Beppe

[SSmolak]

But visible only is excluded from lighting right ? And it is still included in whole exposure calculation...

I mean that background sky should be treat as alpha from exposure calculation. Probably this is not possible in GPU renderers....

[SSmolak]

Hi,

Polygon that has albedo at 255 and HDRI sky which has much more brightness power ( especially its sun ). Exposure system treat HDRI Sun as the highest brightness. Every camera correction or OCIO treat it as highest. After rendering and cutting this backgroud we have rendered polygon not 255 but 200 or less in brightness power. Because of this "overexposured" HDRI. I asked that it is possible to equalize Octane output to 255 in RGB without background power. Maybe with AOV nodes ?

But ok - I know that probably this is not possible because renderer must equalize whole scene not only its part ( geometry only )