Raising the SSS Effect on Genesis 8 human surfaces

nonesuch00

Hey, I decided I wanted to raise the SSS effect on the human skin surfaces with Genesis 8. 

So then I set all the skin surfaces to Translucency Weight = 0.75 (0.0 - 1.0 scale) which as it turns out is too translucent as I can see shadowy areas under the eyelids and lips area that are the models teeth & eyes.

So I need to adjust the dept penetrating of this SSS effect but what are the correct values needed for 0.75?

I think it involves mostly these two sets for the 'SSS' part of the skin and eyes.

a) Translucency Weight = 0.75

b) Base Color Effect = Scatter & Transmit Intensity

c) Transluncency Color = 1.00 0.93 0.90

d) SSS Reflectance Tint = 1.0 1.0 1.0

and

a) Transmitted Measurement Distance = 1.00

b) Transmitted Color = 1.0 0.84 0.76

c) SSS Mode = Mono

d) Scattering Measurement Distance = 0.50

e) SSS Amount = 0.30

f) SSS Direction = -0.50

Thanks.

Fishtales

This might explain it better than me :)

nonesuch00

Fishtales said:

This might explain it better than me :)

Thanks that's what I am reading now...

nonesuch00

OK, I'm half-way through the document

The document is OK but it'd be nice if they updated it and then wrote a written tutorial on the good settings for human skin, hair, fibre hair, eyes, metal, and a few types of textiles, metals, and building tiles for example. Especially human skin, hair, & eyes since those are by far the most difficult.

Anyway, in reading, and frankly making things up in trying to use the various types shader layers in the surfaces for skin different then their intent in order to try and copy the 3 simulated layers of skin I read from paper about 3D rendering of human skin I really don't see good newby guidance from the online document which is who it's intended for. 

The DAZ documentation is difficult to follow it talks about shader layers but it would be nice to have a visual diagram with the various shader layers that document is talking about along with little info blurbs with illustrated circles showing the effects and what layer(s) those effects occur on. It'd need to be a fairly large page to fit on all the shader layers via the parameters choices.

Also there are big gaps in the document that I have no idea of:

1) SSS Scattering: different between Chromatic (adds a 2nd color and removes SSS Amount)

2) That big long list of specular parameters settings.

3) Others?

Fishtales

Chromatic, going by my experiments, changes the colour of the light as it passes through the volume, much the same as a rainbow caused by the light passing through the raindrops. It depends on which colour you choose that is affected by the distance into the volume you have set. Like the sea looking blue because the reds are lost the deeper you go.

I used it to get these effects in this post.

nonesuch00

Fishtales said:

Chromatic, going by my experiments, changes the colour of the light as it passes through the volume, much the same as a rainbow caused by the light passing through the raindrops. It depends on which colour you choose that is affected by the distance into the volume you have set. Like the sea looking blue because the reds are lost the deeper you go.

I used it to get these effects in this post.

OK, that's what it sounded like but that wouldn't be needed for skin, well maybe for a geoshell that was set up to be similar to being wet with water. Good thing I changed it to mono, orginally the PA had chromatic.

The dorking around I've done I like the results but I have to let it render long enough to see how it converges. Then render it again with a close up on the head.

Thanks.

nonesuch00

Well the changes I make take much longer to render but give the effect I wanted but now who can say how to make these new-fangled Genesis 8 characters with a light sheen of skin oil glossiness? With the Surfaces paramerters changes I'm unsure where is the best place to do that anymore.

Thanks.

Fishtales

I came across this although I don't know if it will help. It basically says that the oil on the surface should have a Refractive Index of 1.5, the skin below should be around 1.47 at 1mm thick and below that again 1.47 with/or without a blood map added. All the light entering the skin should reflect away from the camera.

nonesuch00

Fishtales said:

I came across this although I don't know if it will help. It basically says that the oil on the surface should have a Refractive Index of 1.5, the skin below should be around 1.47 at 1mm thick and below that again 1.47 with/or without a blood map added. All the light entering the skin should reflect away from the camera.

Thanks.

I wonder what the real translucency weight of human skin is? DAZ Originals often use & I've tried value above 50% but those only work, sort of, for skin textures that have dark diffuse maps in some lighting situations.

Meanwhile there are new surfaces and no updated documents on how to properly use them: DAZ 3D is supposed to be best at human models but such documentation for their iRay materials surfaces isn't very helpful. Leaving us to 'artistically guess' isn't really flies in the face of  entire concept of PBR and iRay.

+++++

It 'guess' like I should use this * set to mimic the thin horny layer that is the 5 layers of the epidermis

* Diffuse Strength

* Diffuse Roughtness

* Diffuse Overlay Weight opens Diffuse Overlay Weight Squared and Diffuse Overlay Color at non zero values

+++++

sounds like I should use this + set for the oil-sweat sheen on to of the epidermis

+Dual Lobe Specular Weight

+Dual Lobe Specular Reflectivity

+Specular Lobe 1 Roughness

+Specular Lobe 2 Roughness

+Dual Lobe Specular Ratio

+++++

All other layers, if used would be the deeper dermis layer or use for geometry visiblle at the surface (bump & normal maps & such)

Top Coat - should be used for being wet - if a geoshell isn't used. I guess. Some say yes, some say no but PBR is supposed to be more definitive and the layers of human skin are well defined as well.. 

+++++

And that has me confused what the Glossy Layered Weight, Share Glassy Inputs, Glossy Color, Glossy Color Effect, Glossy Reflectivity, Glossy Roughness, Glossy Anisotropy all should be because the DAZ document says to set the Glossy Weight to 0.0 which negates the rest of those glossy parameters, no? And how are those different than all those specular parameters? Are the specular parameters supposed to be creating some sort of SSS effect?

Then there is the Backscattering Weight, Glossy Anisotropy, Glossy Anisotropy Rotations and the documentation mentions velvet and silk.

Refraction Index, Refraction Weight but I can't use that particular Refraction Index on human skin surfaces because if turns it into a transparent surface mostly all the way through a model rather than just the very thin layer that is the skin.

I also read similar to what you have said for IOR.

Well then even though the PBR in these DAZ Surfaces is not supposed to be a guessing game that's what I'll have to do. Thanks for your help.

Fishtales

If you really want your brain fried try this for size :)

I usually set skin to 1.45, leaves I make 1.47 with Translucency set between 6 and 8, hair at 1.47 top coat 1.5 etc. The Refractive Index should give you Translucency without adding the Translucency setting but with leaves, grass and flowers etc. it seems to make them look better, with skin it can be a hit and miss depending on the skin and lighting.

Fishtales

Then you can try these, (I picked all these up a few years ago and fried my brain trying to understand it all, some were fine others were way over my head :) )

http://gl.ict.usc.edu/Research/DigitalEmily2/

http://www.collectionscanada.gc.ca/obj/s4/f2/dsk3/OWTU/TC-OWTU-317.pdf

http://www.photokaboom.com/photography/learn/Photoshop_Elements/color_correction/skin_tone/1_skin_tone_samples_chart.htm

nonesuch00

Fishtales said:

Then you can try these, (I picked all these up a few years ago and fried my brain trying to understand it all, some were fine others were way over my head :) )

http://gl.ict.usc.edu/Research/DigitalEmily2/

http://www.collectionscanada.gc.ca/obj/s4/f2/dsk3/OWTU/TC-OWTU-317.pdf

http://www.photokaboom.com/photography/learn/Photoshop_Elements/color_correction/skin_tone/1_skin_tone_samples_chart.htm

OK, thanks! 

I've still managed to improve it but I made a guessing arty approach & it takes much longer to render.  You links should help improve or at least learn some more than what I have now.