Fiddling with Iray skin settings...

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  • VadrusVadrus Posts: 46

    Does anyone have a way to retain the details from skin diffuse maps when SSS is used?

    Whenever I have got the skin to look soft enough to look OK the SSS effect has overwhelmed the small details from the diffuse map and I end up with a very smooth look with virtually no blemishes.

    I never use a translucency weight higher than 30% and usually have it about 20% but it still seems to become the dominant element of the skin, any tips for retaining diffuse details?

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  • VadrusVadrus Posts: 46

    Here's my latest attempt, V7 HD with just the default diffuse and bump shaders used all others have been removed.

    I was going to render it again in a better setting with the HDRi just lighting the scene but Studio seems to have got a bit crash happy for me this evening so had to give up.

     

    V7 Skin Test.jpg
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  • fred9803fred9803 Posts: 993
    bwise1701 said:

    Could someone tell me what character / texture set this image uses?

    Thanks

     

    This is G3F (Cailin from memory) with V4 London (Metropolitan Collection) skin by danae (Renderosity). I wish she would make some native G3F skins because her V4 ones are fantastic.

  • jestmartjestmart Posts: 4,036

    To Vadrus, I put the the diffuse maps in to the translucency color channel and set the color to a very pale warm pink.

  • VadrusVadrus Posts: 46
    jestmart said:

    To Vadrus, I put the the diffuse maps in to the translucency color channel and set the color to a very pale warm pink.

    Thanks, I'll try that and see how it works.

     

     

  • RAMWolffRAMWolff Posts: 9,598

    Having an issue getting a nice reflective quality on the Cornea layer in the eyes.  Any tutorials on that around?? 

    Thank you

    Richard

  • Oso3DOso3D Posts: 14,250

    Personally, I've gotten great results with just using the Water shader, upping Refraction index to 1.36, and setting Coreal bulge to 1.5.

     

  • RAMWolffRAMWolff Posts: 9,598

    Thanks ... I did try the Thin Water shader but it doesn't work on the Iris or the scleral ... they render black.  I even tried the Crtl option and had it leave the maps alone... rendered black.  Works OK on the Cornea but I need reflective qualities on the rest of the eyes to really make them look more natural.  The Hivewire figures do not have lens bulges of any kind unfortunately! 

  • AndySAndyS Posts: 1,397

    Yep,

    the water shader isn't efficient for iris or sclera.
    btw: The black outcome you observe is the result of the still not solved refraction bug of iRay !
    For iris and pupil I set Glossy Layered Weight to 0 and Glossy Roughness to 1. Otherwise you get a lot of fireflies produced by the multiple reflection between cornea and iris.

    For sclera and lacrimal you should use normal glossy reflection with a roughness between 0.05 and 0.2  It just has to suit your likes. And you can play around with the bump value.
    For the reflecting cornea best is a 0 bump.

  • jag11jag11 Posts: 748
    RAMWolff said:

    Thanks ... I did try the Thin Water shader but it doesn't work on the Iris or the scleral ... they render black.  I even tried the Crtl option and had it leave the maps alone... rendered black.  Works OK on the Cornea but I need reflective qualities on the rest of the eyes to really make them look more natural.  The Hivewire figures do not have lens bulges of any kind unfortunately! 

    Set Translucency Weight to 0 on everything and set all colors to white.

  • jag11jag11 Posts: 748

    A quick render, stopped at 24%.

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  • RAMWolffRAMWolff Posts: 9,598

    Thanks so much folks.  I really appreciate it. 

  • RAMWolffRAMWolff Posts: 9,598
    AndyS said:

    Yep,

    the water shader isn't efficient for iris or sclera.
    btw: The black outcome you observe is the result of the still not solved refraction bug of iRay !
    For iris and pupil I set Glossy Layered Weight to 0 and Glossy Roughness to 1. Otherwise you get a lot of fireflies produced by the multiple reflection between cornea and iris.

    For sclera and lacrimal you should use normal glossy reflection with a roughness between 0.05 and 0.2  It just has to suit your likes. And you can play around with the bump value.
    For the reflecting cornea best is a 0 bump.

    So I tried these settings you suggested but still not quite right.  Are these using the Base Mixing of PBR Metalicity or PBR Spec/Glossiness? 

    Also, how simplified should the set up be, like how many maps... as in just the Base Color map or .....  Here are my settings for the Iris. I know, a bit over done but just experimenting...

     

    ScreenHunter_09 Jan. 22 17.16.png
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  • jag11jag11 Posts: 748
    edited January 2017

    Those settings look like they belong to skin instead of iris.

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    Iris2.JPG
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    Post edited by jag11 on
  • Arnold CArnold C Posts: 740
    edited January 2017
    RAMWolff said:

    So I tried these settings you suggested but still not quite right.  Are these using the Base Mixing of PBR Metalicity or PBR Spec/Glossiness? 

    Also, how simplified should the set up be, like how many maps... as in just the Base Color map or .....  Here are my settings for the Iris. I know, a bit over done but just experimenting...

    Your "Glossy Specular" is way out of range! On a PBR Specular/Glossiness Mix, that should always be the material's 'Fresnel Reflectance at 0°'; this value is based on the Refraction Index (IOR). To get an appropriate value is a bit complex, and also requires a bit of math:

    ((IOR-1)*(IOR-1))/((IOR+1)*(IOR+1)).

    The result is a decimal which has to be put in each of the RGB color channels. You won't find a specific IOR for the Iris' material on the web, so the next logical consequence would be to use that of the material its made of: collagen fibres. Their IOR is about 1.43, so the result for the use on DAZ Studio's color picker would be a value of 0.0313130 [((1.43-1)*(1.43-1))/((1.43+1)*(1.43+1))] for each of the RGB color channels. [When using the PBR Metallicity/Roughness Mix, use a "Glossy Reflectivity" of 0.391412].

    A nice introduction to physically based shading can be found here.

    And if you use a texture map in there, use for it a color of RGB 53, 53, 53; and set the value to 1.00. Anyways, using texture maps in there makes little sense, and the pro of a simple numerical value is always that it doesn't eat up any Video RAM. wink


    Your "Top Coat Weight" is also a 'bit' off: Iray works with values in linear space, from 0.00 to 1.00, and the sum of layer weights shouldn't though be greater than >1.00<. Although Iray will either normalize or clamp sums >1.00, it's recommended not to use values beyond 1.00. Why make it more complicated for the renderer than it should be? Anyways, when making up a material using a Top Coat layer, you should ask yourself first if that material really does have one. And if it doesn't, than simply don't use one. In most cases the "Top Coat Color" will be a neutral 1.00, 1.00, 1.00.  


    Next is "Custom Curve". I know, people tend to set its values to their likings. Which always tells me that they really don't know what they're doing. smiley

    "Top Coat Curve 0" is always the same value which we're also using on "Glossy Specular": >Fresnel Reflectance at 0°<. In this case 0.0313130.

    "Top Coat Curve 90" depends on the optical properties of the material in question. For most, the value to be used is >1.00< (at a grazing angle, an angle of about 90° to the material's surface, 100 % of the incident light will be reflected). That's why we see that white shine at people's contours when they're being lit from behind.

    "Top Coat Curve Exponent": the Iray Uber uses the 'Fresnel-Schlick' equations for its calculations, so the value used there should always be >5.00<.


    "SSS Reflectance Tint" works as a multiplicator for your "Base Color". If your intent was to darken down your Iris' albedo, that would be okay; if it doesn't, I'd set it to its default then (that parameter is merely an artistical color correction tool for the base color; in reality such thing as a SSS reflectance tint simply don't exist).

    For the "Volume" group of the Iray Uber you could try:

    Transmitted Measurement Distance: 0.10
    Transmitted Color: (0.962653, 0.901400, 0.758194)

    Scattering Measurement Distance: 0.01
    SSS Amount: 0.432857
    SSS Direction: 0.80

    That's based on the absorption and scattering optical properties of collagen fibres.


    A very useful tutorial of making up the eye's material, done by DAZ_cjones, can be found here.

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    Post edited by Arnold C on
  • AndySAndyS Posts: 1,397
    RAMWolff said:
    Are these using the Base Mixing of PBR Metalicity or PBR Spec/Glossiness?

    By default the Iray Uber shader is Metalicy / Roughness.
    As Metalicy = 0 (by default) Roughness is a nice measure.

    And after Arnold's scientific description, I like to keep it simple.
    Please keep in mind: the more parameters used, the bigger the workload for the render engine.

    Attached you see the K4 eyes. The cornea got the thin glass shader, which is not really correct (I know!) and roughness is set to 0.05.
    For the iris as I described zero glossy shine and diffuse map only with a little bump. The rest only depends on the quality of the diffuse map.

    Light setup: One small spotlight and some kind of softbox each from around 45° incident angle.

    K4 Eyes Example.jpg
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  • j cadej cade Posts: 1,826

    Ooh my favorite thread is back. And the topic is eyes! That's my jam.

     

    First things first: the cornea and sclera should share the exact same settings as much as possible. In point of fact unless you're using a very fancy translucency with sss setup all settings should be the same. If the settings are not the same, there will be very harsh transitions, look at your eye. Do you see any harsh transitions? No.

    While the eye should technically use sss, unless you're doing a super closeup, the effect is not particularly visible and makes things take forever to render, so unless you're like me and a nutjob about getting the eyes absolutely perfect, its probably best to go without.

    Refraction value for the cornea is 1.377

    Thinwalled on vs off.

    Thinwalled off is infinitely better and more accurate, just... so much better. It is however a bit more fiddly. the biggest problem is that there is some energy loss especially if you have glossy/refraction roughness set to anything other than 0 (this isn't just an iray problem btw, afaik there isn't a refraction model that doesn't have some issues here). In practice, what this means is that with thinwalled off the iris will look darker.

    Also with Thinwalled off you really want to dial in the cornea bulge morph and a morph to make the shape of the iris more natural (hey I've made those! There's a link for that in my signature)

     

    for a visual comparison of thinwalled off and on, hey I already have a visual demonstration ready to go! Take particular note of how thinwalled on looks particularly terrible from the side and also looks just so much less alive in general,

     

    So in conclusion. Edit Cornea and sclera as a unit, refraction value of 1.377, glossy roughness of 0 unless toy get some weird self shadowing on the iris, in which case set it to .08 and accept that it will take a bit longer to render. Morph the default eye shape because it is unrealistic.

    Thinnwalled comp.jpg
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  • Oso3DOso3D Posts: 14,250

    ... If you used the same settings on Cornea and Sclera, wouldn't that make the sclear transparent?

    I'm confused.

     

  • j cadej cade Posts: 1,826

    ... If you used the same settings on Cornea and Sclera, wouldn't that make the sclear transparent?

    I'm confused.

     

    I use a map to control refraction. most characters come with one, It should be mostly black with white where the cornea is.

  • RAMWolffRAMWolff Posts: 9,598
    edited January 2017
    AndyS said:
    RAMWolff said:
    Are these using the Base Mixing of PBR Metalicity or PBR Spec/Glossiness?

    By default the Iray Uber shader is Metalicy / Roughness.
    As Metalicy = 0 (by default) Roughness is a nice measure.

    And after Arnold's scientific description, I like to keep it simple.
    Please keep in mind: the more parameters used, the bigger the workload for the render engine.

    Attached you see the K4 eyes. The cornea got the thin glass shader, which is not really correct (I know!) and roughness is set to 0.05.
    For the iris as I described zero glossy shine and diffuse map only with a little bump. The rest only depends on the quality of the diffuse map.

    Light setup: One small spotlight and some kind of softbox each from around 45° incident angle.

    Could you post a screen grab of your surface settings for the Iris or the sclera?  I really like the outcome there!  Thanks!

    Post edited by RAMWolff on
  • AndySAndyS Posts: 1,397
    edited January 2017

    Hi Cade,

    very interesting informations.
    And I hope, "same unit" only for the glossy aspect.  wink
    Although I'm not sure that my sclera is glossy reflecting like the cornea.

    But btw, what texture did you use? The G1 texture is way too coarse. It creates the typical artefact crossed patterns and don't show these sharp details of your picture.

    That "Thin Walled = off" looks darker is the fault of the still unsolved refraction bug of iRay. If the light enters the refractive surface below a specific angle, it is not present below that surface anymore.
    See 2. picture, where I only used one spotlight from ca. 45° incident angle.

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    Eye Cornea refractive.jpg
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    Post edited by AndyS on
  • j cadej cade Posts: 1,826
    AndyS said:

    Hi Cade,

    very interesting informations.
    And I hope, "same unit" only for the glossy aspect.  wink
    Although I'm not sure that my sclera is glossy reflecting like the cornea.

    But btw, what texture did you use? The G1 texture is way too coarse. It creates the typical artefact crossed patterns and don't show these sharp details of your picture.

    That "Thin Walled = off" looks darker is the fault of the still unsolved refraction bug of iRay. If the light enters the refractive surface below a specific angle, it is not present below that surface anymore.
    See 2. picture, where I only used one spotlight from ca. 45° incident angle.

    Nope my cornea and sclera share all settings other than transmitted distance, transmitted color sss ammount (0 for the cornea here obviously) and sss direction. Best way to guarantee there is no harsh unnatural transition between the sclera and cornea

    In the comparison above I was using the very nice eye product by parris that came out recently, the comparison was whipped up for that so its not completely my usual

    I have to say I don't entirely agree with you on refraction necessarily having a bug. What you're seeing there appears more to be the effect of perfect refraction and a lens. ie tiny light souces get refracted back to tiny points of light (also why we have caustics). infinitely small light sources can make this problem even more irritating. (To make double sure I rendered in Both Iray and Cycles using the same setup and the same effect occured in each. Now I suppose the same bug could be in both, but the more likely reason is that this is simply expected behavior) Now the obvious fix is to add some roughness. However, as I said, in Iray and other render engines making glossy/refraction rough loses energy and tends to takes much longer longer to clear up noise. One thing where other render engines like cycles have an advantage is one can make the eye not cast shadows and so lighten up things that way

     

     

  • RAMWolffRAMWolff Posts: 9,598

    Getting a little closer to what I want but the reflection is sort of hazy and a bit large.  The spot is not that close to the face. 

    Any suggestions?

    Thank you!

     

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    Tina's Eyes... a bit better.jpg
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  • AndySAndyS Posts: 1,397

    Hi Cade,

    I hope you won't deny fundamental physics.
    The light entering through the cornea must bend down onto the iris, not away - as it currently does. That confirms the result of my detailed investigation I did about one year ago.
    For example you may have a water prop. As long as the light enters from high enough, the light transits "under water" too. As you lower the incident angle of the light (somewhat above 40°), under water the light suddenly disappears (against the real live experience).
    And before the "experts" intervene: Yes, I tried it as well with a simple plane as with a volumentric water object.

    I only wanted to warn about using "Thin Walled = off" because of that refraction bug. Under certain conditions you may have strange effects.

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  • Arnold CArnold C Posts: 740
    edited January 2017
    AndyS said:

    As you lower the incident angle of the light (somewhat above 40°), under water the light suddenly disappears (against the real live experience).
    And before the "experts" intervene: Yes, I tried it as well with a simple plane as with a volumentric water object.

    Disagreed. This effect is exactly what you'd have to expect from an application using Schlick's approximation. The more the incident angle of light goes towards 90°, the more light gets reflected. For a water surface with a temperature of 20°C, F(0°) is 0.020059, meaning 2% of light gets reflected, at F(90°) it's 1.0 or plain 100%. On your second render you can still see the pool's walls beneath the water surface, so in this case the amount of light reflected is still below 100%.

    Don't confuse Iray for a render engine that will totally and exactly simulate real-world. For such one we'll have to wait aproximately for at least another 5 decades, according to some hard- and software engineers. Iray's purpose is a tool for "everyday rendering", using simplified methods to do its work. What you see as a bug is effectively Fresnel-Schlick in action.

    Post edited by Arnold C on
  • AndySAndyS Posts: 1,397
    edited January 2017

    Hi Arnold,

    for sure some parts get reflected - the more the lower the angle is. But what you see from my pictures is, that for the light/shadow line they seem to reverse the IOR. Instead going down as stated by the refraction rule, the line moves upwards.
    This very simpe is the BUG.

    Additionally you get an absolute suddenly disappearence of the light at a limiting angle somewhere below 43°. This too indicates, that they used IOR in the wrong direction.
    --> Total Reflection appearing for transitions from thick to thin material.
    That's what you see in the above Eye-picture, too.

    Did you ever visit a public open air swimming pool in the afternoon? So you would know, that you're wrong.
    That portion of the faint under water texture visible is only the result of the diffuse daylight I had in the set. As soon as I use only an isolated lightsource, it will disappear at once.
    And what excuse do you have for the broken contiuation of the shadowline in the first pic?

     

    Edit:
    But since this is OT for the skin shader topic, you can get more details from the Ph.D. of Physics in a seperate thread.

    Post edited by AndyS on
  • RAMWolffRAMWolff Posts: 9,598

    I thought there was a dedicated thread to iRay and eyes but I couldn't find it...

  • AndySAndyS Posts: 1,397
    edited January 2017
    Post edited by AndyS on
  • RAMWolffRAMWolff Posts: 9,598

    Yea, found it.  Took allot of notes with from Cath and Jones to try out tomorrow when I have more time.  Thanks! 

  • Is there such a thing as a good reference guide what all the render options and surface dials do and how they affect the render?  I could really use a good basic knowledge of what all those dials do and why I should twiddle them. :)

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