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Fiddling with Iray skin settings...

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  • agent unawaresagent unawares Posts: 3,513
    RAMWolff said:

    It may come to my starting from scratch but after a little bit of patience and time spending dialing things up and back and what not I think I'm actually liking the results.  I'd like to get a SLIGHT sheen over the skin if possible but this looks ALLOT better and still haven't taken out that noisy dark glossy map yet. 

    You have to put scatter back in too! Come on, I believe in you. That will give the nice reddish glow where light passes through. There should be some along the bridge of her nose at the shadow edge and lighting up her ear. Really would be a nice touch.

    (If you're still using 4.8, scattering in 4.9 plays much nicer.)

  • RAMWolffRAMWolff Posts: 10,249
    agent unawares said:
    RAMWolff said:

    It may come to my starting from scratch but after a little bit of patience and time spending dialing things up and back and what not I think I'm actually liking the results.  I'd like to get a SLIGHT sheen over the skin if possible but this looks ALLOT better and still haven't taken out that noisy dark glossy map yet. 

    You have to put scatter back in too! Come on, I believe in you. That will give the nice reddish glow where light passes through. There should be some along the bridge of her nose at the shadow edge and lighting up her ear. Really would be a nice touch.

    (If you're still using 4.8, scattering in 4.9 plays much nicer.)

    OK.  Searched for Scatter and I have some options separated out now in DS.  I see that the Backscattering is set to 0.  What's a good number to start playing with?  What's a good color to add to the Backscattering Color bar? 

     

    Thanks for the kind words, blush

  • evilded777evilded777 Posts: 2,466

    Ok, so on Olympia its a combination of the bend/twist of the pose and her normal map that shows on her elbows.

     

    On a less extreme pose it actually looks very good.

  • agent unawaresagent unawares Posts: 3,513
    edited December 2015
    RAMWolff said:
    agent unawares said:
    RAMWolff said:

    It may come to my starting from scratch but after a little bit of patience and time spending dialing things up and back and what not I think I'm actually liking the results.  I'd like to get a SLIGHT sheen over the skin if possible but this looks ALLOT better and still haven't taken out that noisy dark glossy map yet. 

    You have to put scatter back in too! Come on, I believe in you. That will give the nice reddish glow where light passes through. There should be some along the bridge of her nose at the shadow edge and lighting up her ear. Really would be a nice touch.

    (If you're still using 4.8, scattering in 4.9 plays much nicer.)

    OK.  Searched for Scatter and I have some options separated out now in DS.  I see that the Backscattering is set to 0.  What's a good number to start playing with?  What's a good color to add to the Backscattering Color bar? 

     

    Thanks for the kind words, blush

    Well, backscatter kind of blurs the surface. The best way I can describe it would be a velvet effect. It needs to be pretty low on skin to look normal, I have it set on mine but I'm considering just turning it off for testing. I'm not sure what the color option does, I'm not seeing it.

    I meant you should do subsurface scattering though. Just set translucency color to a light orange-pink, transmission color to a darker reddish color, then set scattering distance and transmitted distance to about 1.2 (I think this is normal for human skin.) SSS direction somewhere between 0 and 0.5 to get good light scatter through the material without losing the scatter towards the light.

    Then you can fiddle with translucency strength and sss strength to adjust how powerful the effect is. That makes the thin parts of the face redder and lets light pass through the skin to create glow on the other side. I'm not working with a perfect setup here, but see how you can see light travel through on the shadow side of the nose?

    skin 3 settings.jpg
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    skin 3 +0.5.png
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    Post edited by agent unawares on
  • agent unawaresagent unawares Posts: 3,513
    edited December 2015

    Double post, oops.

    Post edited by agent unawares on
  • RAMWolffRAMWolff Posts: 10,249

    Hmm, I did a search for "back" and up came a bunch of options for backscattering.... Backscattering Weight, Backscattering Color, Backscattering Roughness (those last two are grayed out but there is something off with my setup that shows my "hidden" elements regardless if I have them shown or hidden so not sure what the default for the backscattering color should be, I hit reset and it's white so I'll try that).  

  • RAMWolffRAMWolff Posts: 10,249

    Not sure why everyone keeps mentioning "transmission" there is no setting named that.. I see transmitted. so is that what folks are referring to?

  • KurzonDaxKurzonDax Posts: 228

    Let's check a couple of things.

    First, are you using a texture in the translucency color slot? If so, then leave the "color" part of that slot as white.  Otherwise, you can set the color as agent described above.

    Next, look for a setting called Thin Walled and make sure it's set to "off".

    The scattering settings are a group with the following names:

    Transmitted Measurement Distance - setting this to around 1 is usually good.  Between .8 and 1.2 is fine.

    Transmitted Color - There are a lot of opinions on what this should be set to.  If you are using a map for translucency color, then you can try setting this to .9, .9, .9 since the map probably has some scattering already baked in.  Otherwise, you can try what agent describes above.  My preference is probably a little lighter in color, but there is some amount of subjectivity to it.  This setting acts as a gate keeper of sorts in that it alters the color of the light that gets scattered.  Setting it is highly dependent on what you want the overall coloring of the skin to look like, and what your base map and translucency colors are.

    Scattering Measurement Distance - I tend to set this low, between .25 and .5 as that is what seems to be mathematically correct.  

    SSS Amount - I usually use 1.667 here based on a calculation Arnold did a number of pages back in this thread.

    SSS Direction - Of late, there's been a lot of discussion around this setting.  I have been waffling back and forth on whether this should be positive or negative.  I'm leaning towards -0.8, though setting it to a positive value has benefits too.  However.... With v4.8 of Studio, it makes just about no difference one way or the other.

    As for your lack of sheen, that's just because your using a mostly dark glossiness map.

  • RAMWolffRAMWolff Posts: 10,249

    Thank you so much to the both of you.  These are nice settings but I'm still not seeing the scattering.  I did replace, temporarily, the darker glossiness maps and just threw in the detailed specular maps I made and never used just to gauge what would look best.  In their place I did choose .27, .10, .046 to make a soft brown color.  The render looks OK but yea, not seeing the scattering or the play of light on the ears, nose tip or anywhere else we would expect to see a translucency effect.  Closer though for sure. 

     

    Bruna-Little Closer 2.jpg
    914 x 914 - 262K
  • Arnold CArnold C Posts: 740

     

    agent unawares said:

    As you've noted, I haven't actually turned on refraction yet.

    Yes, I noticed. I guess you got me wrong. What I meant was, if you don't set your "Refraction Weight" to something greater than 0.0, that parameter is inactive, it won't do anything. You can try and set it to the maximum, 5.0, even turn off limits and set it to 100.0: your specular reflection won't change a bit.

    If you don't plan to use "Refraction Weight" on your shader setup, you can leave the "Refraction Index" value at the default 1.50. On the PBR Metallicity/Roughness Mix, specular reflection is affected by the "Glossy Reflectivity" parameter.

  • Arnold CArnold C Posts: 740
    AndyGrimm said:

     light penetrates skin way deeper as skin studies show! i can see light trough the bones of my pinky ! ....

    3. TMC is not the skincolor - the skincolor is in translucency and base ( base only if you use colors there)!... tmc is the ratio of R G and B - how much of each channel get absorbed on the distance the light travels in our face (volume)... it affects mainly which color under which angle of VIEW we see most - the color (startpoint translucenc color mixed with base (weight) on the surface volume (transmitted distance 0 ) ! By the nature of absorbation and the final skin colors - TMC is a color CLOSE to the final Skin... which controls what LIGHT projects on our final render.

    Setting up this correct is the challenge...with a limited scatter.

    Then you're the very first person in history on this planet able to do that... cool

    Whatever you want. I won't ask where you got that theory from again. However, I posted the preview screenshots to show the impact of a monochrome Transmitted Color and the loss of control over determine your transmission via the Transmitted Measurement Distance parameter it causes.

    I'm at a point now simply bailing out of discussions about that topic, since it's gettings kinda exhaustive and hasn't anything to do with Physically Based Shading anyways.

  • KurzonDaxKurzonDax Posts: 228
    RAMWolff said:

    Thank you so much to the both of you.  These are nice settings but I'm still not seeing the scattering.  I did replace, temporarily, the darker glossiness maps and just threw in the detailed specular maps I made and never used just to gauge what would look best.  In their place I did choose .27, .10, .046 to make a soft brown color.  The render looks OK but yea, not seeing the scattering or the play of light on the ears, nose tip or anywhere else we would expect to see a translucency effect.  Closer though for sure. 

     

    I did a bunch of testing with subsurface scattering in v4.8 a few months ago with various configurations.  I then took the images in to Photoshop and used the "difference" layering mode to compare them.  Want to guess what I found?  Regardless of what settings I used, if the base color was set to Scatter Only (instead of Scatter and Transmit) there were literally no differences between any of the images.  The problem was that if I selected Scatter and Transmit for the base color, the skin took on the wretched sunburn look like what you had a few pages ago.  Unfortunately, I think you're going to need to upgrade to v4.9 to really get the full effect of the SSS.  The good news is that for me, the latest version (v4.9.0.54) has been very stable.

     

    Arnold C. said:

     

    agent unawares said:

    As you've noted, I haven't actually turned on refraction yet.

    Yes, I noticed. I guess you got me wrong. What I meant was, if you don't set your "Refraction Weight" to something greater than 0.0, that parameter is inactive, it won't do anything. You can try and set it to the maximum, 5.0, even turn off limits and set it to 100.0: your specular reflection won't change a bit.

    If you don't plan to use "Refraction Weight" on your shader setup, you can leave the "Refraction Index" value at the default 1.50. On the PBR Metallicity/Roughness Mix, specular reflection is affected by the "Glossy Reflectivity" parameter.

    I set the refraction index only as a reminder so I know from what value I determined the Glossy Specular color.  However, if using the Metalicity/Roughness mixing, didn't someone (you, maybe?) determine that UberBase was automatically determining the glossy specular color based on what was entered for refraction index?  So for MR, it should make somewhat of a difference if that's the case. 

  • Arnold CArnold C Posts: 740
    edited December 2015
    Toyen said:

    Another one, this time V7:

    Yep, she is in fact a very white girl in disguise. Her skin textures are rather pale and it feels more natural trying to get the skin shader right while staying true to her actual skin texture.

    I wonder why they decided to go with that fake tan look using too much translucency while her skin is actually pale.

    What do you guys think?

    Me, too. smiley

    Me thinks that's a really nice looking Victoria, and that that would be the look I'd expect for her price of $44.95. With decent GlossMaps she'll be perfect. 

    Post edited by Arnold C on
  • TJohnTJohn Posts: 11,227
    evilded777 said:

    Ok, so on Olympia its a combination of the bend/twist of the pose and her normal map that shows on her elbows.

     

    On a less extreme pose it actually looks very good.

    What hapens if you kick the mesh resolution up to 2 or 3?

  • evilded777evilded777 Posts: 2,466
    edited December 2015
    Tjohn said:
    evilded777 said:

    Ok, so on Olympia its a combination of the bend/twist of the pose and her normal map that shows on her elbows.

     

    On a less extreme pose it actually looks very good.

    What hapens if you kick the mesh resolution up to 2 or 3?

    The subdivision level is currently at 2, turning it up to 3 has no visible effect.

    Post edited by evilded777 on
  • AndyGrimmAndyGrimm Posts: 910
    edited December 2015

    @Arnold C.

    What do you mean? angle of view?  or where i am the first person to do that?... did you never notice the glowish red shine close to a spot reflection which comes  sidewards?  this depends on  the angle of view or light...

    and in a good scatter there is somehwere the distance in the volume  where blue scatters back to the surface but NOT red or lower red. but because we have just one scatter distance - this effect is not possible or controlable in iray.


    translucency is actually transmission
    transmission color is actually asorbation color..      here the confusion in iray starts allready... and this is basic physic

    transmission distance is the distanc where the translucency color get's sampled and absorbation starts.

    scatter and absorbation go together -  absorbation colors first base and (i think complementary multiplied translucency  -> then it goes in the scatter.. this stuff does not work seperatly.

    Post edited by AndyGrimm on
  • KurzonDaxKurzonDax Posts: 228
    AndyGrimm said:



    transmission distance is the distanc where the translucency color get's sampled and absorbation starts.

    scatter and absorbation go together -  absorbation colors first base and (i think complementary multiplied translucency  -> then it goes in the scatter.. this stuff does not work seperatly.

    Wait a second, this can't be right.  The absorption has to start at the surface and then increases (I assume linerarly, or possibly along a x^2 curve) until the transmitted measurement distance is reached, at which point the full absorption as specified by the transmitted color is reached.  The reason I say this is that we are generally using a TMD of around 1.  If absorption didn't start until the light reaches TMD, then white light would shine straight through areas of the body that are thinner than this (like the ears).

    Or am I missing something entirely?

  • AndyGrimmAndyGrimm Posts: 910
    edited December 2015

    @Arnold C.

    Mixing base and translucency or what absorbation does!
    This image shows how translucency and base getting mixed.. it uses only absorbation and 50 grey (only 50 grey and white in translucency AND base)....   it shows speratly base  and seperatly transluency on the same render ... if you take weight zero or weight 1 then it means not much.... because you see only the HALF what get's sampled before it goes in the scatter.

    the color in the middle is the end result...(has a LOT to do with colormixing algos ...!.. 



     

    showing translucency and base.png
    720 x 1080 - 329K
    Post edited by AndyGrimm on
  • AndyGrimmAndyGrimm Posts: 910
    edited December 2015

    @KurzonDax

    you would not need a distance then.....   the distance is a HELP parameter. (one sample point).. to simulate what complexe materials do with light based only on the volume in nature!....    absorbation works in TWO (all) direction on a translucent material....

    so you set the distance (thickness - where you sample transmission color (our transluceny map!).....   then the backscatter 0 (liht beam backwards (which is always there.. even when there is no scatter amount.. colors our base...(backwards)



     

    KurzonDax said:
    AndyGrimm said:



    transmission distance is the distanc where the translucency color get's sampled and absorbation starts.

    scatter and absorbation go together -  absorbation colors first base and (i think complementary multiplied translucency  -> then it goes in the scatter.. this stuff does not work seperatly.

    Wait a second, this can't be right.  The absorption has to start at the surface and then increases (I assume linerarly, or possibly along a x^2 curve) until the transmitted measurement distance is reached, at which point the full absorption as specified by the transmitted color is reached.  The reason I say this is that we are generally using a TMD of around 1.  If absorption didn't start until the light reaches TMD, then white light would shine straight through areas of the body that are thinner than this (like the ears).

    Or am I missing something entirely?

     

    Post edited by AndyGrimm on
  • AndyGrimmAndyGrimm Posts: 910
    edited December 2015

    @KurzonDax

    we need the distance paramter to CHEAT our mesh.... because otherwise you could not control how much of (transmssion) absorbation shines trough a nose.. tht's why we all set it somewhere between 1 - 2 cm.. thickness of nose plus absorbation (rest distance from sample to mesh)

    Post edited by AndyGrimm on
  • AndyGrimmAndyGrimm Posts: 910
    edited December 2015

    when you set a LARGE distance.. then the volume start to GLOW.. because ALL light whitout absorbation (white light ).. gets backwards reflected/scattred.too..= luminance goes UP! it is a simplification of  the nature.. not a correct simulation.

    Post edited by AndyGrimm on
  • KurzonDaxKurzonDax Posts: 228

    @AndyGrimm

    Thanks. Let me stew on that a while to get my head around it.

    Meanwhile, here are my latest tests, this time with the ever unflattering midday sun.  I did a little more compressing of the reds in the diffuse texture, and darkened some of the detail (most noticeable in the freckles).  This brought out the detail much better, I think, though I'm debating if it's a little overdone.  I'll be testing with some other lighting later today.

     

    Large 3 Face Tests 2 Midday Sun -1900px.png
    1892 x 904 - 2M
  • Oso3DOso3D Posts: 15,045

    I think I got the skin softness around where I'm happy with it... what do you guys think?

    http://willbear.deviantart.com/art/Softskin-578879379

     

  • AndyGrimmAndyGrimm Posts: 910

    @timmins.william looks like an alien laugh....

    i see you still experiment with transparency.... i also think that transparency is the missing thing..  because i know i can see a splitter in my finger under the skin ...  but  clearly to less paramters in iray to control translucency AND transparency... so i gave up for the moment trying to use both effects on skin...

  • Oso3DOso3D Posts: 15,045

    Hee hee!

    Yeah, for a while I experimented with regular refraction. I was impressed with how much refraction you could use and still have skin look solid. I've mostly moved back to a simpler approach -- for 99% of what I'm doing it doesn't matter. But it's interesting.

    (And I'm fascinated with translucence, SSS, and refraction generally, not just for humans -- fog, water, slime, glass...)

     

  • AndyGrimmAndyGrimm Posts: 910
    edited December 2015

    @KurzonDax

    positive or negative scatter.....

    the problem with negative is not to see in a face render without hard shadows......      

    first, also with a plus-scatter .. backscattering (minus scatter)  is there too....   there is also forward scattering when you set a minus scatter.. but to a lesser extent...

    the real difference we see just when we send light TROUGH a volume....  to get a reddish shadow you would need WAY more light in the minus scatter then using a plus scatter....or setting the translucency weight so strong that it looks like a alien....

    Only for skin - minus scatter is right and probably also arnolds sss amount calculation...   for a VOLUME (nose, ears, face contoures) including shadows,  plus scattering is right.   and adding the tmc distance to represent the thickness where you want light get transmitted and absorbed (aka nose.. seems best... around 1 - 2 cm)..

     

    Post edited by AndyGrimm on
  • AndyGrimmAndyGrimm Posts: 910
    edited December 2015

    actually setting the phase of the scatter to zero (circle)... should do it just fine too - for both (skin AND transmitted through a volume )... 

    Post edited by AndyGrimm on
  • AndyGrimmAndyGrimm Posts: 910
    edited December 2015

    @timmins.william

    same here...   i dont upload skin renders at the moment... because i try to figure out how refraction AND translucency work together...

    i had my second AHA moment as i understood that Irays terminology is wrong.. translucency IS transmitted color....   i remember i said once in this thread...  HECK in a good scatter i dont need translucency this is included in transmitted and scatter enlightened...it does also not help that translucency is not in the Volume part of our shader sections.. 

    @Rashad Carter
    Octane has it right! Daz iray shader confusing a LOT!

    translucency weight is transmitted color weight!

    translucency color(map) is transmitted color (map)

    transmitted color is ​absorbation color.

    Post edited by AndyGrimm on
  • ToyenToyen Posts: 1,917
    edited December 2015

    Testing the skin shader on the palest and darkest G2F skins I have to see the contrast. Although, Lilith's skin is unrealisticly goth pale. I do wish I had Monique right now!


    Post edited by Chohole on
  • RAMWolffRAMWolff Posts: 10,249
    KurzonDax said:
    RAMWolff said:

    Thank you so much to the both of you.  These are nice settings but I'm still not seeing the scattering.  I did replace, temporarily, the darker glossiness maps and just threw in the detailed specular maps I made and never used just to gauge what would look best.  In their place I did choose .27, .10, .046 to make a soft brown color.  The render looks OK but yea, not seeing the scattering or the play of light on the ears, nose tip or anywhere else we would expect to see a translucency effect.  Closer though for sure. 

     

    I did a bunch of testing with subsurface scattering in v4.8 a few months ago with various configurations.  I then took the images in to Photoshop and used the "difference" layering mode to compare them.  Want to guess what I found?  Regardless of what settings I used, if the base color was set to Scatter Only (instead of Scatter and Transmit) there were literally no differences between any of the images.  The problem was that if I selected Scatter and Transmit for the base color, the skin took on the wretched sunburn look like what you had a few pages ago.  Unfortunately, I think you're going to need to upgrade to v4.9 to really get the full effect of the SSS.  The good news is that for me, the latest version (v4.9.0.54) has been very stable.

    Well I guess I'll have to wait to see when the stable final release of 4.9 hits.  I'm itching to get to it but as previously stated I don't mess with beta's.  So hopefully they will have it out the doory by XMas *fingers crossed* as I have 5 days off and will have time then to play.  That IS an interesting idea to make use of PS's Difference setting.  I'll check that out as well.  Never know!  lol

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