Fiddling with Iray skin settings...

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  • Oso3DOso3D Posts: 14,583
    I like using geoshells because you can tweak a lot of parameters at once. Also, it seems aesthetically 'right' to have makeup literally on top of the skin.
  • RAMWolffRAMWolff Posts: 9,710

    Hmm, not played with the Geo shells before.... may have to look into that if I can't find an "all in one" solution... Thanks Will!

  • Oso3DOso3D Posts: 14,583
    Big tips: you probably want to change Offset from .1 to .01 (hugs closer to the skin). There is a visibility set of parameters so you can easily shut off most of the geoshell. If your underlying skin has displacement, it will poke through geoshell unless you set the same on geoshell.
  • JimbowJimbow Posts: 557

    Like I said.... wink

  • Oso3DOso3D Posts: 14,583
    Sorry. waiting on new computer (few more days, maybe?) and forums on a smartphone ... ugh. :)
  • RAMWolffRAMWolff Posts: 9,710
    edited August 2016

    Question about rendering times for iRay.  Sometimes certain skin renders really fast and sometimes they render very slowly.  SO my guess if things are set up and balance your going to get a much speedier render.  Mind you that's just from my weird mind.  So I'm developing a skin set for Dusk.  The 3DL and 3DL SSS versions all render in under a minute.  I did a quick conversion over to iRay using the SSS since there allot more maps plugged in.  I did allot of tweaking and moving maps to different channels and getting the skin looking really good (it's supposed to be Toon sort of skin) but the render was only about 80% at 20+ minutes.  SO thought I'd check in and post my render settings to see if anyone can help me get this sped up a bit more.  The one thing you notice is the map plugged into the Translucency Weight channel, without that mask there the eyebrows go funny colors. 

    PS.  Ignore the map under the Transmitted Color channel, that's since been removed as it doesn't do anything to improve an iota of what I'm after...

    thanks for the help if there is any to be had! 

    Rich

     

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    Post edited by RAMWolff on
  • What about Diffuse overlay?

  • Arnold CArnold C Posts: 740
    edited August 2016
    RAMWolff said:

     SO thought I'd check in and post my render settings to see if anyone can help me get this sped up a bit more.  The one thing you notice is the map plugged into the Translucency Weight channel, without that mask there the eyebrows go funny colors. 

    PS.  Ignore the map under the Transmitted Color channel, that's since been removed as it doesn't do anything to improve an iota of what I'm after...

    thanks for the help if there is any to be had! 

    Rich

    I'd remove the texture from the Translucency Weight channel's texture slot, because a texture map plugged into effectively disables the transluency layer parameter. The same for Transmitted Color, as you've already noticed yourself. Altough equipped with a texture slot on DS's user interface, a texture doesn't work there. (DS version 4.9.1.30, solved on DS 4.9.2.70)

    See the sample renders below. Even with a high value of 0.9 for Translucency Weight, it is still only showing the Base Color on "001" (for testing purposes I removed the diffuse texture there, leaving the Base Color plain white). Only when removing the texture map from the Translucency Weight channel's texture slot, the Translucency Color and the texture map plugged into its texture slot will come into effect, as shown on "002".

    Since the Volume group parameters needing the Translucency Weight parameter to be in effect when the Refraction Weight parameter is at 0.0 (and because that is determining the level of transparency of a material, I'd only use that for liquids, glass and transparent plastic), you also won't get any transmission and SSS effects either. No translucency, no transmission and no scattering.

    Things which have a noticeable impact on render times in Iray are the Volume group parameters (SSS), translucency, lighting, mirror-like reflections, environment (renders in rooms will take longer, because the virtual photons are bouncing around due to walls and roofs) and the distance from the object (figure) to the camera. A figure (with transmission and SSS) will render faster when it's at a larger distance to the camera, and that figure wearing more clothes will render faster, the more of the body is covered.

    Altough both are at a Full HD resolution, the "Magic Falls" render below took around 24 minutes to reach default convergence, the one labeled "11" only 8. On a GeForce GT 730, GPU only.

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    11.jpg
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    Post edited by Arnold C on
  • 3Diva3Diva Posts: 11,083
    edited August 2016
    RAMWolff said:
    RAMWolff said:
     SO thought I'd check in and post my render settings to see if anyone can help me get this sped up a bit more.  The one thing you notice is the map plugged into the Translucency Weight channel, without that mask there the eyebrows go funny colors. 
    Arnold C said:
    RAMWolff said:

    PS.  Ignore the map under the Transmitted Color channel, that's since been removed as it doesn't do anything to improve an iota of what I'm after...

    thanks for the help if there is any to be had! 

    Rich

    I'd remove the texture from the Translucency Weight channel's texture slot, because a texture map plugged into effectively disables the transluency layer parameter. The same for Transmitted Color, as you've already noticed yourself. Altough equipped with a texture slot on DS's user interface, a texture doesn't work there.

    See the sample renders below. Even with a high value of 0.9 for Translucency Weight, it is still only showing the Base Color on "001" (for testing purposes I removed the diffuse texture there, leaving the Base Color plain white). Only when removing the texture map from the Translucency Weight channel's texture slot, the Translucency Color and the texture map plugged into its texture slot will come into effect, as shown on "002".

    Since the Volume group parameters needing the Translucency Weight parameter to be in effect when the Refraction Weight parameter is at 0.0 (and because that is determining the level of transparency of a material, I'd only use that for liquids, glass and transparent plastic), you also won't get any transmission and SSS effects either. No translucency, no transmission and no scattering.

    Things which have a noticeable impact on render times in Iray are the Volume group parameters (SSS), translucency, lighting, mirror-like reflections, environment (renders in rooms will take longer, because the virtual photons are bouncing around due to walls and roofs) and the distance from the object (figure) to the camera. A figure (with transmission and SSS) will render faster when it's at a larger distance to the camera, and that figure wearing more clothes will render faster, the more of the body is covered.

    Altough both are at a Full HD resolution, the "Magic Falls" render below took around 24 minutes to reach default convergence, the one labeled "11" only 8. On a GeForce GT 730, GPU only.

    Sorry to stray off topic - but how did you get the hair in the last two images to look so soft? 

    Post edited by 3Diva on
  • Arnold CArnold C Posts: 740

    @divamakeup

    Oh, I didn't, I had someone doing it for me: Mec4D Unshaven 2 for Genesis 2 Male(s), the Pure Hair: Darling on the "Magic Falls" render uses the "U2 Middle Brown" material preset, and the Thalia Hair on "11" the "U2 Golden Brown" one.

    Select the hair in the Surface tab, apply a material preset, apply the "!ADD SHINE" preset, and you're ready to go, err, render. smiley Very comfortable.

  • RAMWolffRAMWolff Posts: 9,710

    OK Arnold.  I'll check out your info a little bit.  Still working my way through emails!  lol  Never ends. 

    Thanks so much

    Rich

  • RAMWolffRAMWolff Posts: 9,710

    Does the making use of the Top Coat Color and it's other settings do much for skin? 

    I did investigate the drop down Top Coat Layering Method and seems like Reflectivity is really the best! 

  • Oso3DOso3D Posts: 14,583
    I like using Glossy to define dry skin and then Top Coat Fresnel to simulate shinier skin oil.
  • RAMWolffRAMWolff Posts: 9,710

    So far turning off the Top Coat has the render going a bit faster, so far.  3 minutes at 30%.... better so far.  I have found with the newer settings that I needed to up the Glossy Roughness up to about 45% to keep these little white spots off of the skin.  Not sure what's causing those but they look like little spot lights here and there. 

  • RAMWolffRAMWolff Posts: 9,710

    Little over 11 minutes.  I like the skin tone better too! 

     

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    Tommy Skin - iRay 11 Mins.jpg
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  • Arnold CArnold C Posts: 740
    edited August 2016
    I like using Glossy to define dry skin and then Top Coat Fresnel to simulate shinier skin oil.

    That's one way to do it, and the most close-to-reality, when using appropriate values. On skin, there are two seperate layers with different optical abilities directly visible: the outermost skin tissue layer called "stratum corneum" and the oily layer called "sebum". Actually, the stratum corneum layer with its Index of Refraction (IOR) of around 1.55 is a bit more reflective than the sebum layer with an IOR of about 1.50, but it is also a little bit more rough.

     

    RAMWolff said:

    Little over 11 minutes.  I like the skin tone better too! 

    You still have a texture map plugged into your Translucency Weight channel's texture slot, and so effectively disable that layer come into effect, and thus also disable your SSS parameters come into effect, too. DAZ should really rework their Surface Tab UI layout, to only use things that will work. Since at least Translucency Weight and Transmitted Color don't work with texture maps, their texture slots doesn't make much, if any sense.  (DS version 4.9.1.30, solved on DS 4.9.2.70)

    And... Glossy Color for a dielectric is always plain White! Not Grey. You'll get a some unrealistic looking reflections when using colored lights. If you find your skin to appear to much glossy, better adjust the roughness parameter than changing the laws of physics. wink

    Post edited by Arnold C on
  • Oso3DOso3D Posts: 14,583

    I've been setting Glossy weight to 1 and then adjusting glossy color to suit. Is that a bad approach?

     

  • j cadej cade Posts: 2,310
    Arnold C said:
     

    You still have a texture map plugged into your Translucency Weight channel's texture slot, and so effectively disable that layer come into effect, and thus also disable your SSS parameters come into effect, too. DAZ should really rework their Surface Tab UI layout, to only use things that will work. Since at least Translucency Weight and Transmitted Color don't work with texture maps, their texture slots doesn't make much, if any sense.

    I dont entirely agree with this statement. The translucency weight texture slot does have some oddities, but I definitely don't think it disables SSS parameters, I'm running some tests/examples now. Transmitted Color  I agree currently doesnt work with maps.

  • 3Diva3Diva Posts: 11,083
    Arnold C said:

    @divamakeup

    Oh, I didn't, I had someone doing it for me: Mec4D Unshaven 2 for Genesis 2 Male(s), the Pure Hair: Darling on the "Magic Falls" render uses the "U2 Middle Brown" material preset, and the Thalia Hair on "11" the "U2 Golden Brown" one.

    Select the hair in the Surface tab, apply a material preset, apply the "!ADD SHINE" preset, and you're ready to go, err, render. smiley Very comfortable.

    Oh nice! Thank you for the info! I added it to my wishlist. I hope it goes on sale soon, it looks like it would be a great product. :)

  • j cadej cade Posts: 2,310

    Images are still testing but, so far my expiriments indicate maps in Translucency Weight do control translucency strength, however there are certain elements of the translucency with sss that are purely on/off (new information to me certainly) and maps don't control those. So provided the slider is set to a non-zero ammount it will always be on, but you can use a map to control the translucency strength to any value other than 0

  • j cadej cade Posts: 2,310
    edited August 2016

    Alright so My test setup was V7 with no texture maps other than bump and normals, so no textures influencing color.

    So here's translucency at 30%. the control for these tests.

    And here's translucency at 0% (totally off)

    Heres translucency at 30% with a simple texture of a black cross on a white background. The parts of the skin where the image map is white (cheeks ears top sides of the head) are identical to the contol image with no maps and translucency at 30% as one would expect, but the centre of the face, where the image map is black, does not look like the render with translucency off as one might expect. Something funky is going on.

    Here's no maps once again, but the translucency set all the way down .0001%. Now that looks an awful lot like the center of the face when rendered with the control map doesn't it? It also looks a lot close to the render with the translucency at 30% than the render with the translucency at 0, Despite the fact that .0001 is a hell of a lot closer to 0 than 30. This leads to my suspicion that certain elements of  translucency/sss are on/off and on/off along the whole surface. (much like how if you have any cutout opacity the shader is automatically thin walled, and all sss and transmitted color effects go away).

    Just for fun Heres a render with the same map I used in translucency weight stuck in translucency color instead. If nothing else it does indicate one reason why its generally a good reason to put something like an eyebrow control map here rather than the weight slot. All of us here are pretty aware by this point that the stronger the translucency strength the darker the skin gets, so putting a map in that lowers translucency strength like a weight map does makes things (like you're dark eyebrows) lighter, whereas, as shown here, that same map in translucency color darkens things right up. (and also lessens sss strength for reasons I understand but would not be able to intelligibly explain, but will say it does help show why I disagree with Daz's stance on sticking dark red in translucency color)

    also if you look up close look at that nice bleeding effect on the edges of the cross, no reason other than that its pretty cool looking.

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    Post edited by j cade on
  • RAMWolffRAMWolff Posts: 9,710
    edited August 2016

    I'm in a cafe right now so can't comment to much but one of the channels has a mask plugged in for the eyebrows to keep them from being discolored and faded out so perhaps that's what your seeing?

    Post edited by RAMWolff on
  • j cadej cade Posts: 2,310

    And for fun, (or a cautionary example) here's what putting a map in transmitted color looks like. Any map. It doesnt matter they all do the same thing. In conclusion, never put a map in Transmitted Color. Ever. If for some reason beyond the ken of man you like the look just set the transmitted color to pure white (or black for that matter) it will look exactly the same, and not use a map.

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  • RAMWolffRAMWolff Posts: 9,710

    Home and removed the offending maps but as you can see there still is something weird going on... see that white spot on the right shoulder and that bit of black just behind it?  That's not from a spot light or an object so something is strange there. 

     

     

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  • JimbowJimbow Posts: 557
    j cade said:
    but the centre of the face, where the image map is black, does not look like the render with translucency off as one might expect. Something funky is going on.

    I imagine that's because of the way light's bouncing around the volume of the object and affecting the surface from within (behind the surface)?

  • Arnold CArnold C Posts: 740

    I've been setting Glossy weight to 1 and then adjusting glossy color to suit. Is that a bad approach?

    Yep, I'm sorry it is...

    "The tissue cells and oil in the outermost layer of skin are dielectric materials that reflect light without coloring it (whereas metals such as gold color the light that is reflected due to highly varying indices of refraction over visible wavelengths of light.) Thus, a physically based skin shader should use a white specular color. In other words, the specular reflection of a white light from skin will be white, and the specular reflection of a colored light will be the same color as that light—regardless of the color of the underlying skin..."NVIDIA, "GPU Gems 3",Chapter 14 [https://developer.nvidia.com/gpugems/GPUGems3/gpugems3_ch14.html]

    The amount of light reflected is determined by the Refraction Index (IOR) of a given material, in case of the Base/Glossy parameter group of the Iray Uber, by the Glossy Reflectivity parameter when Refraction Weight is 0.0. The appropriate value for Glossy Reflectivity is the result of the formula:

    square((sqrt(Specular Color)/(sqrt0.08)))

    Where Specular Color is the result of: (square(IOR-1))/(square(IOR+1)). Which is is the same method you'd use to determine the correct Glossy Specular color when using the "PBR Specular/Glossiness Mix".] And the amount of glossiness is determined by the Glossy Roughness/Glossiness parameter.

    In case of the general used value of 1.55 for the IOR for the "stratum corneum", the value for Glossy Specular will be 0.046521 (put into each color channel), and Glossy Reflectivity will be 0.581507. For the Top Coat, "sebum" has the same optical properties as the default used polyurethane plastic, so except Roughness/Glossiness you could leave its values alone.

    So, when changing the Glossy Color, you're changing the optical properties of your material, making a dielectric into an insulator.

    Sorry for all the math, but that's how it has to be done to get the appropriate values for Physically Based Shading. angel

  • Arnold CArnold C Posts: 740
    j cade said:

    I dont entirely agree with this statement. The translucency weight texture slot does have some oddities, but I definitely don't think it disables SSS parameters, I'm running some tests/examples now. Transmitted Color  I agree currently doesnt work with maps.

    Intersting test results, j.cade. I (re)ran a similar test myself, using a custom simple black& white map similar to yours. I didn't test it on Genesis 3, because of the lack of default translucency maps for that line of figures, I tested it on Genesis 2 Base Female only, and using DS 4.9.1.30 when it had been published.

    I stand corrected, you're right, texture maps will work in the Translucency Weight texture slot in DS 4.9.2.70 now. Looks like DAZ implemented a change to the Iray renderer or the shader layout to make textures work in there now, and transmission isn't shut off anymore.

    When I ran those test renders posted above, plugging a "V5Bree" TL-map into a TW texture slot did disable translucence completely, and it also disabled transmission in the process. Didn't had a "shine though" effect on G2F's ears then when positioned a spotlight closely behind the head.

    I even opened a ticket back then, but that was closed shortly after the helpdesk guy said he will forward it to DAZ's software engineers. As it looks like they really took a look into it. Mea culpa, I took that as a DAZsoon™ answer, since the problem wasn't that critical and didn't rerun the test when 4.9.2.70 came out. indecision

    j cade said:

    And for fun, (or a cautionary example) here's what putting a map in transmitted color looks like. Any map. It doesnt matter they all do the same thing. In conclusion, never put a map in Transmitted Color. Ever. If for some reason beyond the ken of man you like the look just set the transmitted color to pure white (or black for that matter) it will look exactly the same, and not use a map.

    That's correct. I had a conversation last year with a NVIDIA employee. The transmission parameter of the Iray renderer isn't build to use texture maps, it needs a color made out of floats only to work correctly. She also recommend to NOT use a plain white, red, or any color including a linear value of 0.0/1.0 as transmission color, because "having 0 or 1 in one of the channels of the volumes color will effectively disable any distance based change for this channel and make the material look slightly odd. For large distance it will look red and not change anymore if the thickness changes."

    "ken of man": you're a true scotsman by any chance?

  • JimbowJimbow Posts: 557
    Arnold C said:
    The transmission parameter of the Iray renderer isn't build to use texture maps, it needs a color made out of floats only to work correctly.

    Makes sense. Does that mean an exr/hdr would be okay? It seems to suggest that.

  • algovincianalgovincian Posts: 2,429
    j cade said:

    Alright so My test setup was V7 with no texture maps other than bump and normals, so no textures influencing color.

    So here's translucency at 30%. the control for these tests.

    And here's translucency at 0% (totally off)

    Heres translucency at 30% with a simple texture of a black cross on a white background. The parts of the skin where the image map is white (cheeks ears top sides of the head) are identical to the contol image with no maps and translucency at 30% as one would expect, but the centre of the face, where the image map is black, does not look like the render with translucency off as one might expect. Something funky is going on.

    Here's no maps once again, but the translucency set all the way down .0001%. Now that looks an awful lot like the center of the face when rendered with the control map doesn't it? It also looks a lot close to the render with the translucency at 30% than the render with the translucency at 0, Despite the fact that .0001 is a hell of a lot closer to 0 than 30. This leads to my suspicion that certain elements of  translucency/sss are on/off and on/off along the whole surface. (much like how if you have any cutout opacity the shader is automatically thin walled, and all sss and transmitted color effects go away).

    Just for fun Heres a render with the same map I used in translucency weight stuck in translucency color instead. If nothing else it does indicate one reason why its generally a good reason to put something like an eyebrow control map here rather than the weight slot. All of us here are pretty aware by this point that the stronger the translucency strength the darker the skin gets, so putting a map in that lowers translucency strength like a weight map does makes things (like you're dark eyebrows) lighter, whereas, as shown here, that same map in translucency color darkens things right up. (and also lessens sss strength for reasons I understand but would not be able to intelligibly explain, but will say it does help show why I disagree with Daz's stance on sticking dark red in translucency color)

    also if you look up close look at that nice bleeding effect on the edges of the cross, no reason other than that its pretty cool looking.

    Thank you, j cade, for taking the time to make this post - most useful information! 

    - Greg

  • Oso3DOso3D Posts: 14,583

    So for the amount of glossiness, you are best using Glossy Weight?

     

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