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Exactly! This is why I also mentioned glossy roughness. The powder used by photographs or for TV shows changes the glossy roughness trying to reach a "more perfectly lambertian" BRDF (but not totally). Some of the first gonioreflectometers were conceived for the cosmetic industry for powder testing purposes.... (And for the cars paint on the other side). Well "first" not sure, but let's say that cosmetic industry owns probably much more gonioreflectomers than physics labs!
this is a very handsome photomodel WITHOUT makeup... we did this kind of images often to help (advice) the mask - before a shooting started... (using polaroid - or the model agency provides such images)....
It shows the nose glossy trick which i posted above.... flashlight directly from the lense... you can use the camera headlamp for this.. No offset - no shadows!.. Iso 200.. bring the headlamp down till it looks like this reference image.. and you are set - for glossy fiddling.
EDIT: The Headlamp does not generate glossiness like expected - instead a spotlight on the cameraposition - color5k and about 15 000 lumen does the trick.
lense: Most common a 85mm or 105mm.. about 0.5 - 1.5 meter away from the model. AspectRatio 2:3.. (the example is a crop)
it gives also a good example to adjust the bump map... there is a LOT of bump even on such a beauytful, young skin...(but not on the nose!).
Here's the refraction I'm talking about. It's... incredibly subtle, and I'm not sure it's worth the tweaks, but I think it makes the skin slightly more realistic.
http://willbear.deviantart.com/art/Brandon-test-566206057
Thanks for posting this, Andy. I found a slighly larger and a similar one, dark skin this time (looks like Naomi has dryer cheeks).
(I think, that the reflection distortions would more be a result of displacement (or normal map) than plain bump, pores go down where our bump maps mostly just raise pimples on the skin). Slight bump and a little bit more displacement.
I'd also guess that those powders may affect the glossy specular also, since the materials they are mostly made of (Talc, Titanium Dioxide,...) have all a higher refraction index than any part of skin, so increased glossy roughness and increased glossy specular. But the latter could also depend on how many bucketloads of that stuff you throw on your models.
@timmins.william checked your example... i weigethed it even more to figure out the effect on glossy... but well soon comes the moment where the eyeballs are to see throught closed lids
.... should also affect glossy backscattering... maybe helps with softer edges...; could be worth another try (later).
i am trying now to improve my standard base gen3 and bring her in a pose with ligth and gloss like on the photo which arnold posted.
The first what i do is working a little bit on the bump - gen3 bump really does not work for this .... a short cut will be to flatten the bump on the nose (i try to find a easy solution, just overlay the nose area with grey 128 and blend it in with a graduate )...
Will post again when i have the frontal flashligth check with a better bump.
@Arnold C. saved both of your larger resolution modelphotos to my HD.. great references!
Displacment is the way to go...yes... BUT well.. i dont want start modelling Gen3 from scratch ...But i will add some custom morphs to make the pose more real - because we can use the best skin model.. if such details are not right it will never convince our eyes.
From what I understand what's explained in the "The Appearance of Human Skin" (CUCS-024-05) article, the wrinkles on our skin (picture) are seperated into two types: the primary are wide and deep, the secondary are shallow and narrow and run diagonally to the primary ones. According to "Bioengineering of the skin: skin surface imaging and analysis, pp202–204" (a book which I tend to refuse to get at; € 150,- is a bit hefty, even for me, and even for a hardcover edition), they make the skin surface rough and would also cause a degree of anisotropy depending on their width and depth (I might be corrected on this by an experienced physicist
).
Specular color is a thing that a guy named Augustin-Jean Fresnel discovered and wrote about. Due to him the specular color of a thing is dependent on it's refraction index and he invented a not so complex formula to calculate it. Programmer Sébastien Lagarde wrote a nice article about this (and on PBS in general, so I'd say it's a "must read") on his blog (including the formula and an example). Don't let yourself be irritated by the fact that he mentions a "game" there and then; the basic principles of Physically Based Shading are independent of the render engine used. Since a given refraction index for a given material doesn't change and will be the same for the whole surface, the specular color derived from it's refraction index will always be a set color, for dielectrics it will be a (very, very, very) dark grey, almost black. If you by any chance own Mec4d PBS Shaders vol.1 for Iray, you can take a look on the specular maps she created for pastic f.e. You can open one in Photoshop, or even in Windows' Picture Viewer, and pick the black color. The RGB value will match a RGB specular color value derived from the used refraction index.
The "strength maps" created for the 3Delight renderer doesn't meet the requirements of a PBR environment and "doesn't work very well in Iray" (that's the nicely put equivalence for "they suck"); that's why I tend to recommend MarmoSet's Tutorial: PBR Texture Conversion article. Although too technical for some, the described principles will be valid for any Physically Based Renderer, being it Toolbag, "Dustbin" or Iray. Allegorithmic's PBR Guides are also a good read for those who want to create PBR/PBS shaders and textures... aaaand they are free! No excuse left for not grabbing them.
Although I tended to just use good ol' Fresnel on a Top Coat all alone, I recently was told that that wouldn't be a soooo good idea... V3Digitimes might can explain briefly why, if she wants an has the time for that.
For the Skin Glossy Flashlight reference examples: i forgotten to say that the reference photos are cropped.
This are my settings
pose your model in standard pose on xyz zero
Aspect ratio of 36mm is 2:3 ....(rendersettings)
ISO 200 - rest default
Camera Focal Lenght is 105mm
Camera Z on 100....
Camera Y = eyes of your model
EDIT: headlamp is limited.- does not work.
Set a spotlight on the same position as the camera is.
15000 lumens
Geometry disc 10
color 5000k
Fascinating conversation, guys. I'm interested in getting my renders to be as realistic as possible, and noting wher there is room for improvement.
What Arnold mentions about the structure of our skin is making me think about how dynamic that surface structure is, and how far we still have to go to capture the nuances of it.
Here are some photos I snapped just now of the back of my hand to illustrate one aspect:
In photo A, my hand is relaxed and even though this is just a low resolution photo taken with an old iPad, we can still make out the primary and secondary wrinkle lines in the main specular highlight. My hand is not oily or anything, I wiped it on some cloth to make sure it's clean. I'm mainly lit by a single light in the ceiling directly above me.
In photo B, I'm raising my thumb up as far as it will go, compressing and deforming the skin on the back of my hand. Note how the pattern in the specular highlight changes, and how there is pronounced anistropy visible on the compressed skin over the muscle between my thumb and forefinger.
In photo C, I'm doing the opposite, bringing my thumb and smallest finger as close together as I can in an effort to stretch the skin on the back of my hand as much as possible. This stretching causes the micro wrinkles to flatten out noticable, and that smoothing causes the specular highlight on the back of my hand to be much clearer and brighter.
I'm just demonstrating with my hand, but these movements of the parts of the hand which effect the microsurface and the apparent specularity and glossiness in the skin are happening all over the body all the time. Like if a woman is kneeling, the microsurface of her knees and thighs will flatten out, causing them to appear much more glossy than if she was standing straight. It's subtle stuff, but it all adds up to what our brain percieves as realism and naturalism in a picture of a person. It's the kind of thing (along with myriad other tiny details) that would require more computer power to simulate properly, but I expect in the future we'll be getting closer and closer.
k,,,I tried this out,,this is what I got.
edit:ooops, I had the headlamp set to .10 instead of .15 ,, here's a second render :)
camera position is correct - did you start with a new scene? i think something is not default in tonemapping...
i started with a new scene to be sure... looks like this:
I set teh backgound to grey, but thats all I changed.My character has a darker skin.Maybe thats the difference?
@pearbear your observation is absolutly correct - and there are allready ways to simulate this effects... the only way is absolut accurate microdetails and specular maps for every movement.. you might be interested to read this: http://gl.ict.usc.edu/Research/DigitalEmily/
.
Using fast GPUs - our computers are fast enough to run such a model - BUT... we can not get the needed scan datas ..
I also think that DAZ missed to give us REAL high resolution with GEN3... i dont dont talk about 50k polygons - i want my models with min 500k.. easy on GPU.. mesh does not really take away so much space - MAPS do... for my tests when i have own microdatas from modeling i use always displacment. But discplacement is not supported for morphs!
ok, I figured it out :)
My cameras' focal distrance had changed from the default 450 to 84.3 for some reason.I reset it and now its rendering much brighter.
@icecrmn you must do a RENDER - or switch to Iray viewport if you have a fast enough GPU card.
That was a render, the screen shot was of the iray preview,I had my camera settings a bit of a mess, I think it's sorted now :)
@icecrmn yes - looking good now - in the usally yellowish or reddish and to much saturated colors - same as mine does
Wow, that was pretty mind blowing. Maybe HD Morphs could be capable of morphing linked with joint movements for dynamic details like that.
@pearbear yes - when i see how many people in the net fiddle with skin models in other software in real high resolution - and the market which DAZ allready has - i would come out with a fully rigged 500k - 2mio polygon base character with better eyes better bends ... right now they still target game developers with low poly models. ... however.. back to my bump map for a lowpoly skin model
... and they're already onto DigitalEmily2.
No DAZ format, though. 
I'm more impressed by this, mostly because it isnt a scan, so I think it translates better to how things are made for Daz currently. I also thought this method of how the expressions were made to be more elegant, its more rig based rather than morph (blendshape) based. But I do think a lot of the realism is not in the materials at all. but details like the beginning of this, I mean look at how the eyelid moves.
@icecrmn ...
I need to correct my setup.. i just figured out that the headlamp does not generate glossy like expected.... i tought it is a short cut for what i do using spotligths normaly...
Set a spotligth on the same position (camera) instead headlamp..
15000 lumen
color 5k
Geometry disc 10cm (ringflash)
With full glossy weight it looks now like this:
@j cade yes - that's a impressive work... and he payd so much for all the needed licenses that he must render it 800hours on a PC from 2008 (video description)
... but he did really a amzing job on the closeup
- extrem well rigged emotions...
that' one impressed me too:
DAZ rigging for gen3 improved a lot... it would just be nice to work with real HD too... the technic is there.. more and more costumers update to fast GPU's.. well let's see.
Inspired by the advice and insights of Andy, Arnold, JCade, timmins and others in this thread I retooled my V7 skin materials and I'm really liking the results. You guys all rule. What a cool community we got here.
The first one and last one are lit with HDRIs, and the middle one is lit with Iray spotlights.
Amazing results! Glad I could help in any small way!
Very nice results Pearbear. The skin has a nice softness to it. When small light sources such as the sun strike certain microdetailed surfaces with bump or normal, the mesh smoothing can appear to break momentarily with a sharp transition in shading as exampled along the left forearm. It's not an easy problem to overcome. Often placing the target near an object that is large and brightly colored or even the addition of other types of light sources can help balance out the directional bias of the incoming highlight.
@pearbear your renders looking good - and we can still improve...
I spent some hours measuring portrait photos without makeups and single flash (thats about sunlight for 1/1000 second).... i compeared with my renders using standard DAZ texture..
What is missed in the DAZ textures is BLACK.... so i tried a complete other Photoshop process..... (will post it when i have more results)...
I try to show the textures as i think the artist wanted it . a light TAN is a light TAN!... and it must be in the BASE color... because there we simulate the Melanin. Desaturating and Devibrance change this way to much!...
Here the results ... flaslight 5k, blue dome, sunsky
I also use a HIGHER bump now (still orginal)... 10 for face - and 3 for torso... - works well also for portraits. and close ups
Zero Maps for Translucency or Gloss yet.. original bump map
Glossiness - still only BASE.. because i want top coat use for improvment of brows and add a peach coat effect.
My values for Glossiness are way higher then all other examples i saw - but match reference as good as possible without mapping.. (need to do more tests )...
Thanks guys!
@Rashad Carter - Yeah, I was really experiencing that problem of the smoothing breaking on the third image due to the extreme angle of the small sun light on the heavy bump map. I halved the amount of bump I was using and set the figure's sub-D to 4 which helped a lot, but still didn't fix it completely (like on the forearm especially).
@AndyGrimm - that reflection on the face is looking great. I have an issue when I set bump really high on skin - when I do it the specular reflections look good, but the high bump also causes small dark shadows which make the skin look pitted and over-textured. I get around this by turning the bump settings way up high only in the topcoat and leaving them at low settings in the base layer - it lets the specular highlights have a lot of realistic texture without casting rough shadows on the skin. This doesn't seem to be a problem for you though, since you're getting good results and not even using the topcoat layer yet. I wonder if you've encountered this problem, or if I'm doing something wrong. Also looking forward to hearing about how you're going to do peach fuzz. I've been tinkering with geometry shells to add more possible layers to my skin than the ubershader can. I only just recently discovered the "Create - New Geometry Shell" function, and I think there might be some cool possibilities there for peach fuzz, sweat, oil, and other extra layers that sit on top of the skin.
@pearbear ... until yet i did not see a avantage using top coat without very good microdetails and map for glossiness... also a bump just for glossy dosent make sense to me... i try to bring the bump to the correct level in base instead - searching to find a VISUAL approach, "standard" procedures such as set your flashlight 15k lumen, 5k color, lense 105 , 100cm distance to your model ... then adjust bump and glossy till it looks as close as possible to "X" reference photo or render....
While doing this i just decided to forget everything what i know about PBR (except must have range values).. and use my own knowhow - coming from print and photoindustry. I see that always black is missing in final renders (RGB) - (C;M;Y;B). simple add it. (well i shift red to B&W , and other tricks, later more),
I spent MANY days trying devibranced or desaturated textures aka MEC4d or general PBR advice - and even when the render would looking great - i would had to add BLACK for a calibrated reference workflow.
This ends with a PBR texture which is greyish - but NOT pale. the black part acts now a little bit like melanin .. and translucency color and sss color is way easier to handle but still good to see,
It would be nice to come to a final process which everybody can copy without getting lost
I try to find a free BATCH image processor which can do what is needed for the texture right now.
Top coat -> well... we will see what i do with this, i am not there yet - have different ideas in my mind how to use it,