Hi there, I’m back with another question I wanted to convert a hdri from hdrihaven.com into the ACES primaries inside of nuke. I was hoping you could tell me if my workflow is correct or not?
First I bring my hdri and colorChecker into nuke and set the IDT to Utility-Linear-srgb
The colorChecker seemed over-exposed so I color picked the ground near to where I presume the colorChecker was taken in the hdri and use and exposure node to match the to values of the hdri.
Using the X-Rite ColorChecker 2005 - 2014 Classic - GretagMacbeth 2.0 I match the "mid gray"swatch of the photographed colorChecker using an exposure and grade node.
I don’t claim expertise in CGI and the use of HDRIs, but that looks reasonable to me, except for one thing. You have checked the write ACES compliant EXR box, but selected ACEScg as the colorspace. That check box is tagging the EXR as being ACES2065-1 (linear AP0) which it isn’t. It’s also forcing it to half-float.
Yeah it was only a presumption that it was in the srgb primaries, I emailed the creator of the HDRI but unfortunately he didn’t understand the question Thanks for your feedback Chris, I’m currently reading your book at the moment and learning a lot.
The greyscale seems a bit off - and how am I suppose to compare this to the values in the actual HDRI? They are not the same exposure, that is strange.
I wanted to convert a hdri from hdrihaven.com into the ACES primaries inside of nuke. I was hoping you could tell me if my workflow is correct or not?
Thanks for your feedback Chris, I’m currently reading your book at the moment and learning a lot.