bone structure

[o4saken]

I been using MHX2 to import into blender, then under the options to import you get asked if you want the Proxy (assuming my designed model) or base mesh (basic human) or both, so i used to just use the Proxy, lately i been importing both, then i go into edit the one i am not using and remove the ears, nose tip, lips, make the fingers thinner etc. so that it fits inside my actual model, this way when you add a subsurface scatter you get very realistic results as the model has a " skeleton " to stop excess light bouncing.

Anyway i was wondering if there was perhaps another method that someone more informed that myself can think of, as an example - if this so called skeleton was made into clothes (which i imagine wont work as might delete the model itself) so that it is freely available, instead of me each time having to repeat the modelling process.

[jujube]

I was wanting to turn the skeleton from bodyparts3d into clothes, but you have a good idea there, making an approximation like that. I could make a clothes when I have time; you can post your obj/blend of the edited one.
Or make it yourself I guess? If the geometry is already there, why not run it through makeclothes yourself?

(You can use a duplicate of the human skin, separate it from the original, and set to clothes. Then it behaves as any other clothes.)

[blindsaypatten]

I just want to be sure that I am understanding what you are describing correctly, you are creating two models, with one that is just below the surface of the other? And this improves the result when you render with subsurface scattering?

[o4saken]

yes that is correct, because at the moment now when you add subsurface, its a matter or trying to balance the difference of how light scatters between the the parts that are supposed to go translucent and those that arent, for example..most of the time if you turn it up to look decent on the ears, then the rest of your model tends to look like wax due to the light bouncing within. add a model below, and problem solved.

[o4saken]

Here are some very quick examples i did. by that i mean bad lighting and not the best skin shading set up... but you get the idea.

you can see the ears glowing, whilst the rest is still normal, and the lips are also softer looking

here is a hand without the skeleton, the entire hand looks as if its glowing, from just a sun lamp.. noones hand glows like that

with the skeleton, it is confined to the edges, and web between the thumb, also just a sun lamp. better as its much softer

And here is the hand again with a spot light behind it, this is very close to what a human hand would do with a flash light etc, and not a sun like the version without skeleton - also awesome because it looks like bones underneath

and with a decent bump map and glossiness set right, the result is more flesh like as the nipple is catching light whilst the denser part is not.

and here is the skeleton as clothes, if anyone wants to test this - i cant at work, so i am hoping that it works and it doesnt delete the actual skin when you "put it on"

skeleton.zip

(603.16 KiB) Downloaded 914 times

alternately here is a blend

clothes.blend

(5.41 MiB) Downloaded 951 times

[Aranuvir]

Interesting approach and good looking renders. Though I see a little limit to this technique. When you take a look at your last image, you can see those blocky/spiky looking shading issue, probably due to mesh intersections. I remember, I had seen similar render issues, even created a bug report, before I realized, I was actually importing two meshes. Perhaps a shrink-warp could reduce mesh intersection?

Admittedly, my knowledge about 3S is very limited, rarely using it in the fear I could boil my system. Just an idea: Did you try to set the 3S scale to fairly low values, bump the light source to insane values and correct the lighting issues, you will run in, with the filmic color management?
https://www.blendernation.com/2017/03/1 ... g-promise/

[blindsaypatten]

I've only learned about SSS today after reading this thread so I may have it wrong but...

I think you have your nodes set up incorrectly in that you have your subdermal image feeding into the color on the SSS node. The color input should be the surface color:

Color
Color of the surface, or physically speaking, the probability that light is reflected for each wavelength.
- https://docs.blender.org/manual/en/dev/render/cycles/nodes/types/shaders/sss.html

The subdermal image should feed into the radius input on the SSS node, and represents the fraction of the Scale value distance that light of the respective color (RGB) can travel through the material.

Here is a simplified node setup for illustration purposes:

The primarily red radius input means red light can travel further than the green or blue. I picked this value arbitrarily, it likely isn't appropriate.
The key value here is Scale which indicates how far light can travel through the material before emerging, and is multiplied by the RGB radius values for each color of light. A small value will only affect a small area from where the light enters, a larger value will affect a larger area and may allow light to travel right through an object if it set to a value larger than the size of the object. At 0.025, on a character that is 1.74 blender units (i.e. 1 unit - 1 meter) tall, light can travel 25mm (reduced by the RGB radius values). That's approximately an inch and seems unrealistically large but it may be that light traveling that far would be very dim when it emerges.

A larger scale of 0.075 allows light to scatter all the way through the hand:

So you can get the "only at the edges" effect you want by picking the right scale and radius values, without an internal "skeleton". It might be interesting though to use the actual bone skeleton that Jujube put in the repo if you want to get stark bone visibility. Actually, I'm not sure that SSS models light traveling through an object or just traveling laterally along the surface.

Like I said, that's my understanding from my reading today, use at your own risk. If one of the more knowledgeable people here can correct me if I have it wrong that would be great.

Edit: Btw, I did try your skeleton clothing, I wasn't sure how to test it but in x-ray rendering I couldn't see anything, where normal clothes are visible.

[o4saken]

you can see those blocky/spiky looking shading issue, probably due to mesh intersections. I remember, I had seen similar render issues, even created

No i get that with the base mesh that comes from makeclothes even without my skeleton thing i did there unless i add a subdivision, not sure why it catches shade like that.

[jujube]

It might be interesting though to use the actual bone skeleton that Jujube put in the repo if you want to get stark bone visibility.

Whoops, to clarify, I haven't uploaded a skeleton to the repo yet. I imported the skeleton from bodyparts3d into blender, but I can't turn it into clothes yet, as it's not all-quad. But there is a skeleton in the repo already, uploaded by jwc, and I'm thinking of shrinkwrapping it to the bodyparts3d skeleton.

edit: I opened o4saken's blend file. I changed the skeleton's mesh type from human to clothes, pressed the make vertex groups button, and removed the extra materials. I recompiled and now it works.

[blindsaypatten]

Whoops, to clarify, I haven't uploaded a skeleton to the repo yet. I imported the skeleton from bodyparts3d into blender, but I can't turn it into clothes yet, as it's not all-quad. But there is a skeleton in the repo already, uploaded by jwc, and I'm thinking of shrinkwrapping it to the bodyparts3d skeleton.

Oops, I was thinking of the x-ray skin which was illustrated with the skeleton. Sorry jwc!

Back to SSS, I was really surprised to read on wikipedia: "Skin is a good case in point; only about 6% of reflectance is direct, 94% is from subsurface scattering." One can actually use purely the output of subsurface scattering and get a close to right result. I guess that when I think about the thin layer of almost transparent skin on the surface I shouldn't be that surprised.

I was also interested to see that the ratio of distances that RGB light travels through scattering, approx R=1,G=0.5,B=0.25 the result is what one might call "skin color".

With some experimentation I did determine that SSS will penetrate through an object if the scale and object thickness are appropriate.

Just rambling...