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How am i supposed to control specularity with a metalness map?

polycounter lvl 8
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Olli. polycounter lvl 8
as i understand, a metalness map is a 1 bit map which determines which parts of the texture are metal and which are nonmetal. It then turns any metal parts albedo to 0,0,0 and uses the value in the albedo map as the specular map instead. So the albedo map sort of doubles as a specular map, but only for metallic parts.

How do i adjust the specularity of nonmetal parts?

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  • radiancef0rge
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    radiancef0rge ngon master
    you dont, using metalness its a predetermined value for all non metals. If you want to define specularity of non metals do not use the metalness workflow

    the most commonly accepted and implemented value is 0.04 reflectivity which in HEX is clost to 0a0a0a I believe. My understanding is that this is the case in TB2 and UE4.
  • Xoliul
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    Xoliul polycounter lvl 14
    you shouldn't have to anyway. Put your effort in the roughness map instead, that's where the work should be.
  • NanoTurtle
    you dont, using metalness its a predetermined value for all non metals. If you want to define specularity of non metals do not use the metalness workflow

    To add to this :
    Most non metals have a very similar specular color/intensity (near white gray-ish)
    Metalness should be sufficient for most materials except more exotic ones such as a beetles carapace and (?) oil stains (?)
  • marks
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    marks greentooth
    NanoTurtle wrote: »
    Metalness should be sufficient for most materials except more exotic ones such as a beetles carapace and (?) oil stains (?)


    What you're talking about is Iridescence:
    http://en.wikipedia.org/wiki/Iridescence

    And yeah, to quote the wikipedia article "It is often created by structural coloration (microstructures which interfere with light)." This also happens with a lot of cloths too (diffuse inter-reflection between cloth fibres causing the specular reflection to appear coloured), and I guess you'd want to handle it with a specialized BRDF.
  • Joopson
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    Joopson quad damage
    In my experience, UE4 doesn't quite deal with energy conservation the same way Marmoset 2 does, and it makes using only roughness really difficult to mimic certain materials, like really rough and dull unfinished wood. Because even when the roughness looks right, it's reflecting more light than it should.
  • passerby
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    passerby polycounter lvl 12
    ya hoping there is a shader made for ue4 for the specular workflow like tb2. Gives way more control
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