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PBR 2 spec Vray 1 spec, solve?1

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  • PBR 2 spec Vray 1 spec, solve?1

    about 5 years ago when i was a total nube, as opposed to still nube.

    i was just finishing 1 year of mental ray, and i was getting into rendering plant leaves.

    at the time i had no idea how to use a transparency channel, because i generally used either jpeg
    or bmp neither of which uses one, eventually i photoshopped a alpha matte of my google leaf pic to
    make a black and white pic and piped it into transparency, because i didn't understand the concept
    of a RGBA 4 layer format like PNG or TIFF. ( which eventually i learned )

    next there was the issue of a normal map because the leaf pic i got from google had one but i didn't
    know how to use Ndo (legacy) to make one, or what the significance of tangent, world, and bump was in
    the settings.

    i was using a single poligon with a single face, (so it didn't really matter, but again eventually learned
    that too.) because the reflection and specularity doesn't really play a part until you add height data.

    so, river crossed now we have a single poligon, with diffuse/normal. and i was making the transition
    from mental ray to Vray because of unlimited render nodes, not because it is open source. and i said:

    "how come the mental ray leaf looks good and the Vray leaf looks bland" answer 2 specular channels.
    because mental ray uses: specularity and reflection on differant channels and vray uses specularity
    as a extention of reflection.

    (57.34+min youtube v=OY_Lef_K84l)

    therefore the specularity showed up as a sharp white flash, where the reflection shows up as a soft fade to
    the frenel. and in vray it just shows up as either one or the other not both. after spending 1 year
    studying vray, such as 12hrs gnomon forest, ndo function, RGBA, normal tangent vs world, and getting
    ok results with sun/sky, hdri, domelight... i learned 'Vray doesn't have 2 specular channels'

    now when you see some the of the stunning shots from star citizen, they have 2 or even 3 specular
    channels on some of their shaders, and the effect is breath taking you say i wanna play that game.

    but vray still just one.

    so i was studying toon shaders and they are talking about facing angles and layered ramps with spline
    and linear connections and i said couldn't you just use a ramp to define specularity? with a 3 color
    toon shader and use the specular highlight as the facing angle to the light, and the second color as
    your reflection with a spline fade to frenel, and our third color as a transparency to show all the hard
    work we did on our diffuse shader. or redundantly couldn't we pipe the export files from Substance Painter
    into the toon colors 1,2. and then layer them with our vray diffuse texture on a seperate shader?

    just a thought, since i have been studying vray for 5 years now and everyone is hot on PBR and substance mari
    and so on, but vray is mum on the topic...
    Last edited by bobtype1; 31-08-2019, 06:20 PM.

  • #2
    For the purposes of look development and physics, specular and reflection in VRay should be considered the same thing. To get two reflection lopes in VRay just use the VRayAlSurface material.
    You can also get 90% of the way there with VRayBlendMtl (not proper energy conserving, but you can alleviate that with some manual tweaking).

    I don't know what you're asking about with the toon shaders and substance painter.
    __
    https://surfaceimperfections.com/

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    • #3
      In substance they call it 'metalness' but it just looks like reflection to me. All my classes are pushing PBR materials and when you translate to Vray you lose a texture.

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      • #4
        Oh duh...

        I am still using 3.6 Maya
        https://www.chaosgroup.com/blog/understanding-metalness

        This says it comes standard with 4.0 next.

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        • #5
          I saw this last month, Andrew lebrov...

          https://m.youtube.com/watch?v=fAKCwAwIPMg

          Where he talks about render engines for 10 min
          And doesn't actually do a render, so if you like starting at a guys face for 10 min he describes biased vs unbiased render engines.

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          • #6
            Sorry, this guy is talking nonsense: https://www.chaosgroup.com/blog/the-...ased-rendering
            https://www.behance.net/Oliver_Kossatz

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            • #7
              It has been my experience scientists are dogmatic and can't agree if the sky is blue Grass is green and water is wet.

              But when you have a dragon and a unicorn riding a spaceship with lazers do you really have to be accurate?

              That was why I quoted lebrov, he suggested all special effects are biased by nature. so, if 2 or 3 specular highlights looks cool I say give the customer what they want

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              • #8
                No offense, but I'm really having trouble figuring out what it is you're trying to say or ask at this point.
                Why are you now talking about unbiased/biased? That has nothing to do with PBR, which is mostly something of a marketing term to describe a couple of new features in game engine shaders to make them behave more like offline renderers like VRay, but without the overhead of multiple materials. And metalness has nothing to do with multiple specular lopes, and does very much exist in VRay, mostly to more easily accommodate assets coming from games. Where did the dogmatism of scientists come in?
                It sounded like all you wanted to do was to have two spec/reflection lopes in Vray, which IS possible with VRayAlSurface.
                Last edited by dgruwier; 04-09-2019, 06:08 AM.
                __
                https://surfaceimperfections.com/

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                • #9
                  Sorry dgruwier. From what I understood unbiased means real-world accurate, and biased means fake, which metalness falls into. Which is an argument into accuracy, and scientists love to argue. Someone else's salesman.

                  As far as PBR, I am studying substance painter and it seems a salesman thought it was slick to point out the one option I don't have in 3.6

                  Which I i tried to re-invent, with a toon shader. But as you pointed out has already been done in Next.

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                  • #10
                    I checked it out, Vray 3.6; and it does not have a pbr metalness input, but ai surface does have 2 reflection slots
                    ​​​​​which would work for a 2 layer specular highlight as I described in mental Ray with a soft lope and hard lope.

                    To tell the truth I haven't used 3.6 since I bought it 2 yrs ago. First I had license troubles, then when I got it debugged a salesman crashed my system and said I needed 4 next.

                    Really in my workflow it's 60% modeling rigging animating, 5% lights (ussually 1% GPU), 15% shader/texture, 10% rendering CPU, and 10% compositing.

                    I don't use a renderer that much... I was thinking of doing a tuber on it. The cost of hardware/software vs. time in a proffesional job. And pushy salesmen are part of that... It's not that I don't want to buy next but it's been a slow year, and pushy salesman are a factor in that too.

                    It seems they ambushed me with a $250.- software, (substance) to pitch a $4000 upgrade (Next) which I can't afford just now.

                    And I am babbling online like an idiot, while in fact not working or earning making next farther away.
                    With the allure of doing a bunch of renders and drawing diagrams to explain how a 2 or 3 spec lobe would look in a imaginary project when I have 3 paying jobs on my desk right now not getting done.


                    I retain a toon type fake lope would render faster real time even, but that sounds like shader look dev for unity unreal and not my area of art.

                    Thanks for responding dgruwier, that's better than Autodesk has done for 6 yrs.

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                    • #11
                      You should give the two articles we posted a read:
                      https://www.chaosgroup.com/blog/the-...ased-rendering
                      https://www.chaosgroup.com/blog/understanding-metalness

                      In short, no, unbiased vs biased does not mean real vs fake, and metalness is not inherently particularly fake, only if you don't use it correctly. In Vray it's just an option that can be enabled to make a given material shader behave like a highly accurate conductive metal shader. The only reason it's called metalness and can be mapped, is to make it compatible with what game devs use.

                      A toon style fake lope probably would be a lot faster, but also not very accurate, so it's not really VRay's MO. If you're looking for fast, look into Blender and Eevee. You can transfer a lot of offline rendering skills into that because it exists inside an environment built for offline rendering.
                      __
                      https://surfaceimperfections.com/

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