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"including desaturating the diffuse texture map and creating her own normal and displacement maps AFAIK. "
As far as I can tell desaturation makes no difference to Iray. I've been using substance painter to work on a texture for a project I am about to submit and it produces desaturated maps. The items in this product have a new and an old version and I did the base/new in paintshop like I always have in the past and then pulled it into painter to age it and then exported those new maps for the old versions. As far as I can tell it makes no difference to Iray if it is desaturated or not. Nor does it seem to have any impact on how the object looks in 3DL. The objects in question are wooden so they have very minimal translucence and sss input, but you would think that would make the difference more obvious if anything.
Be cautious with displacement. Iray does not just love it. I would guess that characters have enough poly's in some cases but you don't want to be stuck upping the subd if they don't for some reason.
"about the color - blood is always red ! i dont see a need for a color map."
Except where it is blue and don't forget the fat padding on some parts of the body. I'm not sure if that matters though because I am still not 100% clear on how far the sss bounces and how much.
Well half the blood under the skin is blue, and then there's all those organs and fat. In theory thickness maps should be largely unnecessary with properly set up sss. It might be useful for areas like the skull and nose where the bone is directly underneath the skin, but beyond that it really more down to using the correct values in the sss settings.
Side note, if you're using the extended settings for sss that include reflectance tint, any pap you stick in translucence weight will override the numerical value rather than being multiplied with it. It's really annoying.
yes - even sss should use a map... sss (distance) on the skull is not the same as on the nose...
colors : blackskin (way more melanin) filters MOST ligth waves under 600nm...... it is even more important to see RED as the main translucency color for black skin types then it is for caucasian types (more blue).... asia is somewhere between....
blackskin has 600 - 800 nm - minimum 3 times more then green and blue (lowest)...... 600nm is yellow, 700 is red > 750 is infrared.....
So just use a 100% red and a thickness map then adjust the strongness to blackskin (lower then caucasian) that should be the best simulation which is possible in iray right now.
Actually, now I've gone back and looked at Darius, the 'thickness map' is what Cath refers to as an albedo map and I have included one of them. We need to standardise terms then we don't get confused as to what we're on about.
CHEERS!
You say SSS should use a map, but what kind and how do we set one up!?
As regards the last part, that is precisely what Cath does when setting up her albedo maps, something I will go into in my tutorial.
CHEERS!
sss - back scattering works in ALL direction (not just the thickness (aka distance to bones like translucency)..... as far as i know there is no automated process to generate 100% accurate maps automatic. Most convincing results i saw using the normal thickness map just a little bit brigther, so that even on the skull is SOMETHING (thickness map are 100% black there -> photoshop and tweaking the grey amount).....
Thickness maps are generated automatic from a high def mesh (best results) using ray tracing...... ( they work well for the head but not for the body!)
there are different solutions to create them.... if i find the time i will upload one for a gen2 later tonight.
Yes. I remember that posting of her. It's somewhere in the "Show Us Your Iray Renders. Part II" thread. I had a bookmark for that, which unfortunately doesn't work anymore since DAZ in their kindness turned the forums upside down. Thanks for that...
I remember theese kind of maps, I did some myself back then. I guess you just confused the naming of the slots they would have to put into. (Made a quick overview picture). The "color catcher"/SSS map is meant for the Translucency Color texture slot (the green X within the green rectangle) to mask out the eyebrows etc. to save them from receiving the red color tone from the Translucency Color RGB color channel, and the albedo/diffuse map would go into the Base Color texture slot. They are not meant for the Transmitted Color texture slot (red X within the red rectangle). Well, I could ask the lads and gents from NVIDIA if a texture map will work in that place, but from what they told me about the Volume properties I doubt that a texture there will work in a good way if any.
Trying the values I gave for the Volume properties on Darius is a bit unfortunate, since they cover the properties for the caucasian skin type, and the good guy is most likely more of a negroid skin type. There are some remarkable differences between them, f. e. the absorption properties of a negroid skin type are way higher (based on the data I found more than three times higher at 700 nm in the red wavelength range), and scattering properties only just a bit (less than twice). I got some measurements for asian and negroid skin types, but their drawback is they do only cover the 650 - 1000 nm wavelength range (red/infrared). For the 450 - 550 nm ranges you might be able to just extrapolate the data, but there's too much room for errors for my taste. I'll keep looking.
Glossy Reflectivity and Glossy Weight are tricky. You'd need some good and valid BRDF measurements for that. Unfortunately they are a bit hard to come by. What you can try is set your Glossy Layered Weight to 0.00 (shutting it down), turn the Top Coat Layering Mode to Fresnel, IOR around 1.52 - 1.55, Top Coat Roughness to 0.7 ("PBR Metallicity/Roughness"), or 0.3 for "PBR Specular/Glossiness", add a Top Coat Thin Film recommended above and let Monsieur Fresnel be responsible for the reflections. Top Coat Weight is the most trickiest part, 1.00 looks a bit too high and seems to blow diffuse and translucency. I'm currently working on that to figure out a appropriate setting.
albedo fiilters the colors (difference to diffuse - or let's say it simulates the melanin amount) while a thickness map would create REAL physic distances but is very hard to create - best results would mean the use of a albedo AND thickness map.
The main difference between translucency and scattering is: translucency shows direct ligth (the sun shines trough ears noses and fingers - > thickness map..
SSS is to see best in SHADOWED parts of the face - where there would be a hard shadow it is just a SOFT colored (redish) shadow (scattered AND filtered light (albedo), leaving the skin!
Ok well, that being the case I completely screwed up, LOL!
I'll go back and switch things around!
CHEERS!
Sure, some of the settings will make no large noticeable diferences, but to know how things would work being close to real-world physical properties will save you from making remarkable errors, like choosing a slightly wrong Refraction Index for your reflective material or putting in a weird and just plain wrong 186 grey into the Specular Glossiness slot.
What is this standard optimized thing you speak of? I hope you're not talking about the basic shader setup for the Generation 7 figure line, for the 1.00 in the red RGB channel for the Transmitted Color just turned out to be nowhere near anything valid.
The desaturation was recommended for the older Generation 6 characters like Vicky and Mike 6, for their diffuse textures turned out to be a little bit too reddish for Iray in the first place. And using a red color for the Translucency Color made it even worse, giving your character a "red-lobster" or "serious sunburn" look, as I had put it.
The reason why blood looks blueish for us is a result of absorption and scattering of incident light returning from subcutis depths by haemoglobin and tissues. It is in fact from the same red down there if extracted up here.
Or, like my former physics teacher would put it: it is actually of any color except blue, for it turns out blue for us it's 'cause it's the color which it reflected back. Tell that ten year old kids. Show them a red box and then tell them that damn thing isn't actually red. Good thing is she was a really cool one and not every improper remark did find it's way into the school reports.
Mmm, I'm getting the odd feeling that wasn't what she meant. I think that albedo map was developed later to go in place of the color catcher. Look at the image when you put the albedo map into the base colour:
Where's all the detail gone!? I think the way I had it set up before was correct. This is why we need accurate intel.
CHEERS!
@rogerbee - the albedo map is used to filter wavelengths ... good to see in your example... the red lips filter other wavelengths then on the brown chin ..
albedo is a diffuse map without any shadows or reflections and should not be oversaturated (which many of the old skin textures are)
Yes this map goes where you would pick a single color for scattering.... but add RED... it should work..
THERE is a name confusion .. because in PBR albedo maps replaced DIFFUSE textures.. while still many skin shaders use a desaturated albedo map in addition to red for scattering.... i talk about the later! ... thickness map is at work.. loading up later.
http://www.nature.com/jid/journal/v117/n6/fig_tab/5601313f1.html#figure-title
Black, asia, caucasian ->
3 skin types -> wavelentgh measuring on the back
No worries, the worst thing you could have done is to completely discard any absorption.
I already went over to the NVIDIA forums and asked about the usage of a texture in a Transmitted Color texture slot. Just could take some time to get an answer, I guess they're sometimes very busy over there.
Well, then my memory striked me on that. I didn't try them out that much, the color catcher seemed sufficient enough for me. I prefer to use less textures possible to avoid my video ram getting overflooded.
This is the sort of "desaturated" map that susbstance painter ends up with. The two images are basicaly the same though the lighter one has some dirt and lightening of the text when rendered. But the text is only nominaly faded (a dark brownish rather than blackish) and not white. Both render pretty much the same with the exception of the aging changes. In other words the two textures are going to give pretty much the same results.
That was what I figured, so the albedo map where Cath puts it, in the Translucency Color channel, is correct. In terms of the Transmitted Color, what I did was to take each body part in turn and pick out it's colour. The main thing to remember is that, unless the figure is heavily backlit you won't see the scatter effect that everyone seems so hung up on anyway. Apart from the ears, most skin is too thick for that to make any difference. I adjusted the IOR to what Arnold suggested though.
CHEERS!
And that in terms that you don't have to be a mathematician to understand would be.....
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You know what, the more I think about it, we are basically fiddling with a shader that I don't think was set up properly for PBR's in the first place, I mean, look what you get when you load the Iray optimised MAT for G2, 3Delight style maps all over the place, plugged in where they shouldn't be. No wonder there is so much confusion! We NEED a proper Iray shader for skin, set up PROPERLY by someone who has at least worked with PBR's. Mmmm, sounds like Cath to me. I think we should cool down, sit tight and wait to see what she comes up with. Once we have that, then we will have a proper jumping off point. I don't think that mucking about in the dark with the current shader is going to get us very far.
CHEERS!
Thanks Andy, good find. For our IrayUber SSS we would more need the reduced scattering (μs′) and absortion coefficients (μa) than overall diffuse reflectance, but as I see there are some weird formulas given in the Appendix which could be of use.
Aww right, de-saturating wouldn't be the correct term for the procedure MEC4D recommended, it's more de-vibrance. http://www.daz3d.com/forums/discussion/comment/809252/#Comment_809252 and http://www.daz3d.com/forums/discussion/comment/809714/#Comment_809714. You don't touch Photoshops "Hue/Saturation".
I digged and found one of the testrenders I did back that days which doesn't violate the forum TOS.
Sorry for her baldness. 
Same sun-sky lighting, same shader setup, except on the the left one a desaturated texture at -60 (in Photoshop) is used, and the right one made with the untouched Victoria 6 texture. Face and legs of the default texture contain a bit too much red for my (and MEC4D's taste).
I have been reducing the vibrance in my diffuse maps, and using albedo maps. Still, I don't think this will work properly in the shader we're having to use anyway. From what I can tell, most of Cath's renders have been done wth betas of her new shader and not Iray Uber.
CHEERS!
Partially true. The reason why 3Delight style maps are all over the place 'cause f.e. specualar maps aren`t in the place they should be. If PA's would have taken some care, they'd put them rather into specular stregth, where they belong to, then into specualar color, where they don't. The main reason why the script doesn't work that well is the 3Delight sloppery which lasted over years.
Well, the IrayUber is a Musketeer... one for all.
And even for skin it isn't that bad: you can do a sufficient 3-Layer-Setup (epidermis/dermis average on the Base, stratum corneum on the Top Coat and add a Top Coat Thin Film for the oily layer). To simulate human skin in a more proper way, or better in a physical correct way, is a bit outside Iray's current capabilities, many methods are too much simplified for that, and it seems it wasn't really meant for that in the first place. If you look for a decent skin MDL even for the older 3ds Max and Maya Iray versions, you'll have a hard time to find any useful.
To simulate the heterogenous madness aka skin mostly physical correct, you'd have to be able to make a 5-Layer-Setup at least, from outer to inner: sebum, stratum corneum, epidermis, dermis, hypodermis, and determine specific thicknesses and characteristics for them. Sebum does only specular reflection, stratum corneum specular reflection and low scattering/absorption, epidermis and dermis only scattering/absorption, in different strengths, and hypodermis is the great backscatterer which sends the light back to the skin surface, passing all subsequent skin layers for a second time.
You may imagine that a shader like that will have a large impact on rendertimes. I'd say, even if one could create something like this, it would't make him much friends, especially among our CPU only users. When I headed over to the NVIDIA forums to investigate, since I didn't get any answers here I had something like that in mind, but I learned that that would be a most impractical approach.
Nevertheless, what we can do, is use as much valid data we can get our hands on, for it will get us the most near to real-world result Iray is able to deliver. What we'd also need are textures that are essentially aimed for PBR usage only; specular-, gloss- and roughness-maps and the like. That would result in different texture maps for 3Delight and seperate ones for Iray use, like Fly028Design Nathy already started to create.
yes - the mainproblem is still that there are no skins with proper additional PBR maps!
in PBR diffuse should be PALE... or like we named it above a desaturated diffusemap or albedo...
SSS would need still a SSS diffuse map (also made from a albedo... or minimum a weight map (thickness)
Translucency needs a thickness map -> i'm just struggling to create one right now, like usally all the tools i use for baking cant handle multi tile UVs and that's maybe also the reasons why there is not one skin offering proper maps yet..doing research right now ... but. well i overlooked Fly028Design Nathy ... thx @Arnold C... are the maps good?:-)
Normal map or bump should match the details on the skin (pores).... but are not just copies from the "photo" skin texture...(that means really scultping a 20 mio polygon model first - to get all the proper maps, just saying
roughness maps are not really needed but because the micro details are usally not accurate.. well here we go :-)...
And we did not talk about peach fuzz yet
SSS is to see in direct light -> the light travels in/behind the skin and "leaves" the skin on another place (distance)... that's why shadows in a face are not just hard edged - > 2cm or more which would be dark are lite and dark reddish from this effect... scattering is also a big part of the final skin color (this shows the graphic which i posted above)...
Most examples which i saw here.. inlcuding your darius above have way to less SSS and also more translucency would give him a more a live look :-)..
If you use a paler diffuse skin -> then sss and transluscency must compensate the colorloss...
Shadows: The shadow under his nose is way to hard because the nose does not transmitt enough light (translucency and scattering).
The Irayuber shader is a MDL shader. MDL is quickly becoming the standard PBR sharder language and studio is not the only program to use it currently. It goes beyond Iray and Metalray and more programs are adopting it as they add PBR. In fact, the beauty of the MDL language is that a shader created for program A in MDL will work the same in program B. The Devs worked with the Nvedia folks when they were setting it up so I think they likely set it up "properly" and they have worked with PBR. Most of the presets that they created and people have built off use metallicity/roughness rather than specular/glossiness. The reason they selected that one as the primary is because Nvidia suggested it. It seems that people are just less prone to screwing that one up. In other words if there are issues they are more likely to lay on the "artis" side than the "code" side.
"If you look for a decent skin MDL even for the older 3ds Max and Maya Iray versions, you'll have a hard time to find any useful."
Because in a situation like that the settings without the maps is nearly worthless. If the maps are set up in a program that creates PBR maps then the maps may be expected to carry the vast majority of the data rather than have multiple strength adjustments etc. If I do a skin (though at this point it would be a nightmare) in susbtance designer I could pull a load of maps. Everything from the expected diffuse and normal to 3 different scattering options. Even if the maps are created in a more tradional way they are going to be variable. Everything in the room with the person being photographed is going to influence the way the skin looks. The skin itself will influence the maps and levels that get pulled from it and so on.
I only hope PAs keep providing 3Delight version textures, I think they are the best for Iray renders. I only need diffuse, specular and bump textures. The attached image features Ryze, I posed him in a way to show translucency in the nostrils and the ears at the same time. As always, no prework, no postwork, no skills.
Actually, Iray Uber isn't that bad when you cotton on to the way Cath was really using it. It was when I was looking at her gallery that it fell into place. She was using WEIGHTED as the top coat layering mode. Her albedo maps were correct and she was plugging that 'shadow catcher' map into Translucency Weight. Remember that info she gave about the ratio of luminosity to translucency with regard to those maps, that was correct too for what she was doing. This is why using search engines for info can be dangerous and why mods plain should NOT lump tutorials in with other stuff. Information gets buried or diluted, people go off half cocked and link the wrong info to the wrong things.
Here is Boris with Cath's info correctly applied:
Everything she did now makes sense. However, I did hit one snag, it doesn't work for her textures that have painted on hair, and I have yet to fathom why. It's fine on eyebrows and beards, just not hair. I think this is why none of her gallery renders feature textures with painted hair.
CHEERS!
I tried out the weighted settings on Darius, and boy what a difference!
Also, if you want to control the shine, you adjust Top Coat Roughness. Now all he needs are the scattering settings. It would be nice if we could have them as colours and settings and not all that formula stuff, I suck at maths!
CHEERS!
Ok folks, major newsflash....
FORGET ABOUT ALBEDO MAPS!!!!
These were a major bum steer where what we're doing is concerned. (Cath must have been using them for her own projects.) You could say I'm being hoisted by my own pitard here as I didn't follow my own advice! What you can do with diffuse maps is to decrease their vibrance. This function is in Photoshop from CS3 onwards and it's also in PT Photo Editor, if, like me, you only have Photoshop CS2. If you want to do this you decrease the value by -60.
Anyway, you do NOT put ANY map in the Translucency Color, this kills the scatter! What you do is to put a shadow catcher map in Translucency Weight. If you're lucky and your texture came with greyscale SSS maps, then you can use them for this. If you don't have an SSS map you can make a shadow catcher map in Photoshop by desaturating the diffuse map, upping the Levels by putting 2.20 in the second box along and then up the contrast by +60.
I'm still not sure about the scatter settings, but, Darius now looks a darnsight better than when we last saw him:
You live and learn, ah well, that's a tutorial I no longer need to write, LOL!
CHEERS!