Hi MtB
Here you find 9 pages of study eyes at CGTalk 
Pilou
Well, I know your sick of seeing him so I will end it with this last one.
thanks everyone.
That last one looks really life like. Before you finish, what about some eyebrows?
Oh yeah, I’ll finish him up…it just seems that I am more excited about this material discovery then anyone else. 
Last time this happened, it was the toonshader…thought I was on to something…found out that playing with the toonshader was old news here. Though I dont see anything about realistic skin materils in the quicklinks.
Maybe its because the idea of SubSurface Scattering is a little novel for one…and seemingly exclusive to high-end programs for another. You know, at another two forums, in two seperate threads for high-end progs and its gurus, I asked for help in identifing SSS in a custom ZBrush Material. I though, If any place can help me figure this out, its the people who use it and understand its properties. I Didn’t get any help at all save one person. Either these people feel that sss in ZBrush isnt possible…or…its old news. The other problem is I have to finish a clients CD layout. I am talking everything: traycard, CD print and an 8 sided booklet. Plus, I have a renderosity tutorial to write and very little to write on.
Thank you for your comments everyone.
Cheers!
Im sorry but what is the material discovery you speak of?. I just got back from a break but I read through this thread and your latest heads do have a very convincing surface indeed!.
However I have no idea what subsurface scattering (how its achieved) is, of course with that name I can make a rather qualified guess.
How does the highend apps do this then?, and how did you do it in Zbrush?. Or what is it exactly that you want to do?.
I apologize if this has already been answered or perhaps its common knowledge, but personally I have no idea =P.
Okay, surface scattering is just that yeah. The name gives a good idea. The scattering of light about or below (or seemingly 
below) surface Normals. Different materials do this differently. Velvet scatters light on its surface hairs. Wax scatters light (SUB-surface scattering) internally giving it an almost self illumination. Skin is a combination of both. You have the translucency of the layers of skin combine with surface hairs. Then, there are other things to worry about. Other things to make it more diffused like pores, wrinkles, and scarring.
All of this stuff makes skin one of the hardest things to simulate in 3D…until the recent future. I don’t know exactly when. Take a look at Final Fantasy-The Spirit Within. Excellent film…monumental even! The skin however still didn’t cut it. Now, take a look at golum from LOTR. Enough said…lol.
High-end modeling programs allow for the layering of shaders. This is one factor. They also have the ability to control certain aspects of the material past normal properties like luminance,displacement (BIG here), alpha masking, and volumetric. Now, in C4D, there is ChanLum. This add-on allows the material to simulate a fog like layer above the regular material. It controls the thickness of this layer, density, fall off, and other parameters like which surface normals to analyze. Something like this makes it very easy to simulate a layer of extra fine hairs to translucent skin with fine pores and actual skin noise (uneven color achieved outside of the texture). The translucency of the layers of skin, even the red diffusion due to the blood in the skin.
Oh my, thats a complicated material!
Now I was thinking, it sucks that you can’t take a gel shader, drop it on an object, then take a second material…ah…Oh! a Spherical blend, drop that on the same object, and then have it interlace itself with the first material and make…AH! 
. Then, I thought, “Wait just a minute now!! ZBrush does have interlacing materials!” 
DoubleShader, DoubleDots, and DoubleSphericalBlend are such materials. So, step one…a major step…was complete…Interlaced materials. Not exactly what I has hoping for but damn close enough…
I have to go home now so I will write part 2 of this when I get back to the computer. Wait until you see what it took to figure out what to use…where…and how…and even when!
BTW-Yup, Making a tutorial. Full details.
Be right back yall!
edit
I will also say that ‘Discovery’ was the wrong word. The material has always been there. I was enlightened to its potential. So I change this that to, for lack of a better discription, specific material engineering…which is what we all do anyway really. Well, should be doing anyway. lol
The material to use would be DoubleShader1 (though DoubleShader2 is the same). DoubleDots and DoubleSpherical will have their own uses too but this one was picked for its full adjustability of both shaders. Next, to figure out the what, where, and when. The material has two shaders. Each shader having its own layers. I say layers because they too have an order. The top layer is your specular. Under that is your diffusion. You can have Colorize diffuse in between those! Very important. Same goes for Colorize Specular between the specular and colorize diffuse. lol
So you can see how this can make a nice transition alone. Don’t forget to add a touch of HDR. It is one of the best additions to the materials. Now, I would like to better understand how both materials are interlaced with each other. As in S1 in relation to S2. there must be some PS type blending going on. That being said. S1 is your subsurface. Thats right Wet bloody muscles! S2 is your tanslucent flesh. The properties of S1 Diffusion are to vanish under direct light and allow S2 and even a texture to show. S1will come out when the light hits a wider angle (there is the scatter simulation) and then almost fade to black under shadow. This is closely tied into the ‘when’ which will be explained in a minute. S1 Specular acts as an over all moisture setting. It’s curve is very smooth in transition. S2’s flesh is to be thin at a wide angle to fake light hitting S1…when it comes out. I mean when by the fact that a material’s curve…any curve, tells it to do something when light hits a certain point. So S1 diffuse curve can be set to not show color when the light is at its peak luminance, be fully diffuse and present when light is in the middle of its transition to dark. When the diffusion is almost back to where it started.
By doing this with the diffusion and specular curves of both shaders, you get the feel if light changing throughout the surface at different points. The Colorized Diffusion and specular determain the main components of your skins color. S1 will be the blush of the skin using reds and oranges of medium to heavy tones (at 50% colorize). In S2, you pick your skin color (also of lighter tones and colorize levels).
All of this can be adjusted to taste. The reason why I use about a 30% to 50% colorize was to allow the models texture to still come through.
One last thing. S1 has a tiny amout of noise to simulate pores. Also a touch of color bump. S2 has alot of big noise at a light touch…this is to simulate the natural uneveness of skin and its diffusion. Color bump to let the texture come through. This is all at the exact draw size of he images posted.
If you have questions or I think of more I will post again…lol.
My eyes hurt…no speel in adys…thud
Karasuando had make something particular for a such dithyrambic answer ? 
You have fluent quick repartee
Pilou 
Wow thanks for the indepth reply Mahlikus!. This is very interesting stuff and I will try it out as soon as I get home, and see if I can make something of interest.
I never did manage to create a good (realistic that is) human skin…so I ended up never finishing my models =/. I’ve been mostly painting for a good while so Im a little rusty now tho =P.
Looking forward to the tutorial .
Your Welcome!
Here, Just playing around with the baked final.
Hair is a mess because I didnt want yo spend the time yet in making a stencil in PS. Just hair doodle.
have to get back to work work…
Another point. I must stress the importance of Nice and powerful ZMode shadow for a great render.
Intensity 94
Lenght 385
ZMode (Turn this on One light only. Main light Recommended)
Blur 2
Rays 251
aperture 25
A three point lighting setup would hurt as well.
I think its the best Zbrush human face I’ve ever seen.
That hair is done really well.
Hi Mahlikus
This is a very interesting path of discovery you are showing us and your results have been getting better and better.
With your latest image, he looks a little pale though so I’m wondering if you might add some warmth to the colours, perhaps just in the darker areas.
I have been working on some models of people and have also been thinking about how to go about representing the skin with materials and textures.
My first thoughts were to try to do it using a single material and texture in an all in one solution. Of course, ZB doesn’t offer what high end apps do in terms of being able to achieve subsurface scattering (such as layering materials), but then they have different purposes.
The high end apps need to be able to do this because the models are often being used for animation so will be seen ‘dynamically interacting’ with light sources. ZB on the other hand, when used alone, is for making static images.
Given that ZB materials can’t be exported except as part of a baked image, I was leaning towards the idea that the best results might not come from trying for an all in one solution, but rather by the selective application of different materials in different areas depending on the scene’s lighting (e.g. different materials painted on in the areas of light, dark and high shine (glancing light)).
These are just the roughly formed thoughts of an often confused mind, so please know that I am in no way trying to diminish your efforts. Rather it is my mind trying to grapple with the method of ZB; having had it for a couple of months I still find it hard to keep the 2, 2.5 and 3D balls in the air at the same time.
I’d be interested to hear your thoughts, and I for one will be putting what you have shown us to use (I haven’t even looked at those double materials).
Good luck with your experiments!
:) :+1:Thank you and I am glad this may help.
Here is an old image with the new materials.
The robe is a doubleSpherical.
I think this is it!!
Well done MTB!!!
Tnx for sharing your tecnique bro!! 
I must say it’s a bit of an information overload, I chose ZBrush because of its ease of use. 
However that’s just me, I would have liked to have helped but until you posted the explanation I had no idea what you were on about.
Your studies have paid off, although the difference between consecutive images is not great the progression from initial to final is immediately apparent.
The result is a convincing degree of realism, well done for sticking at it.
yay mahlikus,
the very last one looks great in terms of color, warmth, hdr, and material
The skin looks great (a little toomy lee jones like )
great achievement
Hi Mtb
Astonished works
he he you have change the lights eyes
Similar is more convincing
Pilou
Ok, looking at this from a traditional illustrative background, I feel that the skin has a slight dead look. Often, human skin has a lot of reds, yellows, and respectively oranges. The reds often build around the cheeks, mouth and nose, while the yellows work more into the jaw and forehead. Also, a subtle green and blue often find there way into the bags under the eyes and beneath the nose - perhaps also working there way under the cheek bones. All of this needs to be very subtle mind you.
Also, working a greasy T area into the face, that is to say some shininess around the forehead, nose and chin would also aid realism.
On looking at the images, I feel some work on some stubble or 5 O’Clock shadow may also help.
Please don’t get me wrong, I think your images are outstanding, but this is how I would look at it traditionally.
The most important thing to remember though is subtlety.
Thank you all for the great comments. Yes, thank yo frenchy for the link…did help tons with the eyes.
Lazarus, Thats exactly the ultimate goal. Find all the sudtleties and work them in. Now as much as I would like an all-in-one skin material, it isnt possible. There are some things like tone that can be added or adjusted with 2.d tools. But right now, ZB doesnt have all the material abilities to simulate true skin…But I am finding out that it is still helping get closer to it.
Thanks again everyone. I’m back on it…
edit- testing a head in C4D with ChanLum (SSS)
