IRAY Hair Translucency

marblemarble Posts: 7,500
edited March 2021 in Daz Studio Discussion

I've noticed a recent problem when rendering some hair - particularly OOT products. The two renders below illustrate the problem which turns out to be fixed by setting Translucency Weight to zero. The thing is that I have renders from a few weeks ago which don't show this problem yet, if I load the scene now and render it, the Translucency needs correcting. So I can only assume that something in DAZ Studio 4.15 (IRay?) has changed. The two renders are of the same hair but with Translucency Weight set to zero on the second render.

Everyday Updo.png
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Everyday Updo NT.png
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Post edited by marble on

Comments

  • marblemarble Posts: 7,500

    I tried and saw the same problem with other OOT hairs - Marlene Hair and Various Age Bob Hair. The effect is introduced when I go the the Materials and click the OOT supplied "Apply This First" setting.

     

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  • dawnbladedawnblade Posts: 1,723
    There is a known issue with transmapped hair, and also opacity (such as a billboard) when used with volumetrics in 4.15. Nvidia was informed of this issue, so it was the driver that was given to Daz developers that is the problem, nothing Daz can do until Nvidia fixes it. This is according to the great folks in Daz support, in response to my ticket about it. There is an example of it by Sevrin. Give me a few so I can find the post.
  • dawnbladedawnblade Posts: 1,723
    Here is the link to Sevrins's post, which includes an example of a billboard with a volumetric, and the 2nd example is the issue with hair. https://www.daz3d.com/forums/discussion/comment/6401756/#Comment_6401756
  • marblemarble Posts: 7,500
    edited March 2021

    dawnblade said:

    Here is the link to Sevrins's post, which includes an example of a billboard with a volumetric, and the 2nd example is the issue with hair. https://www.daz3d.com/forums/discussion/comment/6401756/#Comment_6401756

     

    This happens for me with just a base G8F and the hair in the scene. No volumetrics (I don't think that I've ever used volumetrics), no billboards. It seems to be only OOT hair and only some of them but it is definitely zeroing the Translucency Weight setting that removes the problem.  If TW is set to anything but zero the problem appears and it is not gradual - it is constant at any weight setting.

    Post edited by marble on
  • no__nameno__name Posts: 88

    marble said:

    I've noticed a recent problem when rendering some hair - particularly OOT products. The two renders below illustrate the problem which turns out to be fixed by setting Translucency Weight to zero. The thing is that I have renders from a few weeks ago which don't show this problem yet, if I load the scene now and render it, the Translucency needs correcting. So I can only assume that something in DAZ Studio 4.15 (IRay?) has changed. The two renders are of the same hair but with  set to zero on the second render.

    Instead of setting Translucency Weight to 0, I change every hair surface (except the cap) that use 1.0 cutout opacity to 0.99. Should fix it (I read that solution somewhere but don't remember where).

    image

     

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  • marblemarble Posts: 7,500

    no__name said:

    marble said:

    I've noticed a recent problem when rendering some hair - particularly OOT products. The two renders below illustrate the problem which turns out to be fixed by setting Translucency Weight to zero. The thing is that I have renders from a few weeks ago which don't show this problem yet, if I load the scene now and render it, the Translucency needs correcting. So I can only assume that something in DAZ Studio 4.15 (IRay?) has changed. The two renders are of the same hair but with  set to zero on the second render.

    Instead of setting Translucency Weight to 0, I change every hair surface (except the cap) that use 1.0 cutout opacity to 0.99. Should fix it (I read that solution somewhere but don't remember where).

     

     

    Thank you - that worked like a charm. :) 

  • Steel RatSteel Rat Posts: 398

    Thanks for this. I was having the same problem with the Karla hair in 4.15.

  • vozolgantvozolgant Posts: 207

    daz: 4.15.0.2

    Setting the cutout opacity to .99 fixed the problem.

    Anyone know when this will be fixed? 

  • JovanniJovanni Posts: 87

    Setting the cutout opacity to any value below 1 actually sets the "Thin Walled - ON" parameter.
    This means disabling the following parameters: Transmitted Measurement Distance / Transmitted Color / and SSS parameters.
    In theory, this makes the hair worse. At least not the way the hair creator intended it to be.

  • Richard HaseltineRichard Haseltine Posts: 102,231

    dantist22121991 said:

    Setting the cutout opacity to any value below 1 actually sets the "Thin Walled - ON" parameter.
    This means disabling the following parameters: Transmitted Measurement Distance / Transmitted Color / and SSS parameters.
    In theory, this makes the hair worse. At least not the way the hair creator intended it to be.

    This is a workaroud until nVidia is able to fix Iray and we get a DS update with the fixed version, not a denial that there is a real issue.

  • charlescharles Posts: 849
    edited May 2021

    I've found using a gradient map on cutout, and setting it to about .8 works pretty good at softening the ends of dforce hair.

    Gradient used attached below.

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    hairtest1.png
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    hairfademask1.png
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    Post edited by charles on
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