I need to read this twice to really understand it :- D And for anyone who wants cheaper alternative, get the colors from CultureHustle. It's not on same level, but the super-white is really..really white.
I've had this talk with him about two years ago, fore the past article, and came to same conclusion then. The 50-230 RGB range that Substance popularized seems overly narrow range exactly because they interpreted Albedo differently than most rendering software devs did. Albedo always being measure of total reflectance (thus Specular Reflection Albedo + Diffuse Reflection Albedo), while Albedo of most PBR shaders in non-metallic mode being just the Diffuse part, on which the Specular part is added up. And then Corona itself does shanenigans like substracting a bit from that former value, which is super inconsistent feature.
(My personal opinion is that the rendering software should either never modify Albedo and expect users to somehow get physically correct maps&values from Megascan, X-Rite, etc... OR, always substract the base non-metallic reflectance of 4perc. not only if users use higher than 230 value).
And while above 230 seem rather rare, below 50 (4perc. linear reflectivity) seems to be quite common for lot of dark materials. Corten for example being example I've shown at SOA in 2014 while showing first IR build of Corona :- ) At that time, PBR wasn't yet a thing, and this was my guess-work.
My suggested approach for people who want to quickly extrapolate these maps from common photos (so not calibrated scans, personal or 3rd party), is to use the kind of tonemapping that gets you closest to what cameras do. And Cameras use almost extreme S-Curve contrast by default. Not even default ACES OT tonemapper than Corona uses now is contrasty enough to mimic it. If material with ACES OT + 3 Contrast (for example) looks like a photo under neutral exposure, you guessed the Albedo roughly correct.
« Last Edit: 2023-07-16, 15:02:01 by Juraj »
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