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f0 to IOR online calculator?

Hello Everybody! so I have been learning a lot about PBR materials and their uses, and that f0 and IOR is one of the essential things to achieve a realistic effect on materials. so I have figured out how to obtain f0 values from IOR online but have not found easy f0 from IOR calculators. some calculators give the IOR to f0 conversion but require more values which I do not know. can somebody help me with this?


  • Eric Chadwick
    If you're using metal-rough PBR, you don't need to mess around with IOR, the metalness takes care of it for you. 

    There's a few cases where you may need to manually force IOR values, but they're pretty rare.

    What renderer are you using?
  • poopipe
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    poopipe high dynamic range
    I've seen this formula floating around 

    Specular (f0)= ( ( IOR − 1 ) / ( IOR + 1 ) ) ² 

    that puts acrylic (IOR 1.49)  at 0.0387 which is 0.5 which is what everyone works with.. (the 0-1 range in a specular/specular level map being 0.0 - 0.08 normalised)

  • voidseeker0_1
    Hi Eric : I am using redshift and use spec gloss workflow, the thing with metalness is that, there is no control over different dielectrics in the same material. but in specular workflow it is possible.

    poopipe I know the formula and the process to derive f0 from IOR and using math to derive IOR if f0 value is present.
    but that I feel is the long way. there are many calculators present online but i do not know how to use them, that is my problem.
  • poopipe
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    poopipe high dynamic range
    im not sure what you expect from a calculator - if you plug the IOR into that equation you get the f0 value.  all any online calculator is going to do is wrap that in html/javascript - I've not done any web development in 17-18 years but I'm pretty confident it'd take about 15 minutes to google up way to turn the maths into a web form

    with a metal/rough workflow there is usually a separate specular level channel available -  you can pump the dielectric specular values into that.
    unreal has it, substance supports export although I'm not sure if they've actually attached it to the shaders yet (we use our own shaders) 

    its left out in most cases because it's a lot cheaper to leave it out and for the vast majority of surfaces at game type view distances it really doesn't matter. 
  • voidseeker0_1
    can u suggest those calculators with links and a simple walkthrough? I am having trouble finding them.
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