Just so you know, LabPBR is currently being thoroughly discussed and debated. Understanding and interpreting how industry standards work and which ones are de juro and which ones are de facto standards is also a bit confusing if not misleading.
Turns out the way most shaders have implemented specular functions vary a bit and results are somewhat unreliable.
Zombye released an updated Spectrum version as of today 2020-05-16 which supports LabPBR 1.3 and should implement LabPBR as it’s supposed to (or at least the way it was intended from the start).
Future Vanillaccurate versions will remain as they are of course, but the “linear” add-on pack might change a bit. I’ll also modify/update/fix some of the shader descriptions regarding how they interpret smoothness as things continue developing (or at least as I get more details on the subject).
Bottom line is, I’ll probably rename that pack to “rougher” or “lower smoothness” or something just for shaders that would tend to have a higher base smoothness overall, for whatever reason.
I also released a new version of the converter which adds functionalities to apply a SQRT or POW curve to smoothness, should you need to adjust a pack to look better with a specific shader. It’s not an ideal solution but it’s a crutch we could rely on until a standard emerges and gets widespread use.
For now, all LabPBR shaders should be able to use the Vanillaccurate LabPBR standard pack. Older PBR shaders usually rely on “low smoothness” (i.e. “linear”) values but it can also vary a bit.
- Continuum 2.0.x has broken speculars so using a lower smoothness pack or add-on makes sense.
- Continuum 2.1 alpha is a bit smoother than other packs, but looks mostly OK with LabPBR.
- SEUS Renewed (1.0.1, E2) seems to be in a weird place, it’s much less smooth than PTGI. Using OldPBR might look too rough but using LabPBR might break things as it’s not LabPBR compliant. I think I’ll need to change how I generate OldPBR…
- SEUS PTGI is definitely quite a bit smooth, much like Continuum. The way it handles smoothness seems to yield much more smooth results than most other shaders. Using a lower smoothness is however too rough. Further investigation is required but it seems to be more correct to use LabPBR even if it is a bit too smooth.
- Spectrum seems to be the most “LabPBR compliant” one. In its 2020-05-16 incarnation that is.
- Kappa 2.2 seems a bit rough, but it should handle LabPBR correctly. Use default LabPBR pack with this.
Please note that all of this is purely indicative and could very well change on very short notice. I’ll keep you all informed.