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Metalness Gulbrandsen edgetint

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  • Metalness Gulbrandsen edgetint

    Hi,

    I've been researching how to setup metals correctly in Vray. I've looked at the blog post and was wondering how to get the values in the metal chart. I've found on the forum that you can use this code to get those values and some graphs.

    Click image for larger version

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    the Solid line is the Vray, small dotted is Gulbrandsen and large dotted is the complex fresnel

    The way the IOR for a given metal is found is in a for loop with trial and error and not mathematically derived from the real world n and k values. That doesn't seem very elegant.

    But I've noticed a problem in the Gulbrandsen calculations for the fresnel. The edgetint wasn't setup correctly in those calculations.
    When I fixed them and tried it again, these are my results

    Click image for larger version

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    We can see that the Gulbrandsen fresnel is exactly the same as the complex fresnel and that by comparison the Vray fresnel of

    I've made a pull request on the original github so you can look at it



  • #2
    We have already changed the way V-Ray calculates the metallic Fresnel to be more accurate. The Github repo and code there are no longer relevant and I will hide the repo.

    Best regards,
    Vlado
    I only act like I know everything, Rogers.

    Comment


    • #3
      Could you share how V-Ray calculates the metallic Fresnel at the moment? I'm trying to make it compatible with the Gulbrandsen method, so I need to figure out how to get to those base, reflection and IOR values.

      Comment


      • #4
        Could you share how V-Ray calculates the metallic Fresnel at the moment? I'm trying to make it compatible with the Gulbrandsen method, so I need to figure out how to get to those base, reflection and IOR values.
        V-Ray now uses the exact same method - i.e. complex IOR n,k values are derived from the base and reflection colors and the refraction IOR value is ignored. You should not have to do anything on your end.

        Best regards,
        Vlado
        I only act like I know everything, Rogers.

        Comment

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