Tone mapping passes vs beauty

[seandunderdale]

Hi guys,

We're using Maya 2017 and Vray 3.5.

My question is regarding "exponential tone-mapping" and whether using that, you should be able to still create the beauty render using AOVs in nuke. To be more specific, if I set my scene to Exponential tone mapping and dial in some values for bright and dark mult, can I expect my lighting+GI+refl+refr+spec to perfectly match my beauty render? We are trying to use tone-mapping in a car configurator at render time as the nuke script does not allow for a lot of creative flexibility. Currently our nuke op is having trouble getting the two to match.

Any help would be greatly appreciated. I don't really need a fix for the issue, but just to know if this behavior is expected with exponential.

[seandunderdale]

Just to expand...what our ideal workflow would be, is rendering an exponentially mapped look frame, and then recreating that exact look in Nuke. We are rendering a material select for the car paint and creating a base and a gloss pass that is combined in Nuke, but trying to match to the tone mapped image is proving tricky. Is there anything anyone can recommend for going about this?

And as mentioned before, we are also trying to use all the usual passes of a tone mapped render to recreate the beauty tone mapped render and the passes dont match the beauty. Is this expected when using Exponential as a tone mapping method?

[sharktacos]

I'd suggest keeping everything linear in both the render and comp, but applying the tonemapping on the view transform in both Maya and Nuke. That way you stay linear, and see everything the same across your pipeline. You can do this either with OCIO or possibly by reading a LUT into the Maya view transform (although I'm not sure whether the VFB works with those).

[seandunderdale]

Cheers Sharktacos, we are going down that avenue now. We are taking my tonemapped render into Nuke, running a match grade node and exporting a LUT back out for everyone to use.