Hi all, I have been using the search engines only to turn up no viable information on this, so I was hoping someone could shed light on this for me; or, more especially, direct me to a good tutorial.

I have noticed that many of the new 3D models for DAZ Generation 4 figures and up seem to have special..."SSS" shaders and the like applied to them. Upon examining their materials in the Materials room, I have observed that they have elements such as "Blinn".

I am only familiar with traditional material values such as diffuse, specular, ambient, etc.

Can anyone shed light on how these shaders work or how they are applied, or perhaps direct me to a good tutorial?

Blinn is a type of specular setting. There's quite a bit of information on it to be had on the net. While not Daz or Poser specific, the information would still be helpful I'm sure.

 That said, if you're looking to use Blinn in Poser, just go to the Advanced Material room, right click in an empty space in the material section and choose New Node>Lighting>Specular>Blinn

Playing with the node is probably the best way to figure out how it works.

if I may try: when light hits a surface, it gets sort of captured and re-distributed again, but not in equal amounts in all directions. As a result, surfaces which face tha camera are brighter than surfaces which make a skew angle, and so, objects appear darker at their sides than in the middle. I toss "shading" as the word for it (to separate it from shadowing which is something different).

Regular Poser diffuse as well as specular implement the "Lambert method" for this angle-dependant intensity falloff. Which calculates pretty fast, is not that bad for the diffuse part of smooth surfaces, but is far from realistic for porous surfaces and for specular, turn everysurface into a hard plastic one.

So Poser offers alternatives, and has made some improved versions of those over the years. Clay is the alternative to diffuse, and Blinn is the alternative to specular. Diffuse does not have other main alternatives, specular has Glossy and Phong which are considered outdated, Anisotropic which is meant for surfaces "with a direction" like brushed metals or vinyl disks, and the recently added Ks_Microfacets. The latter is not available Poser 8/Pro 2010 or earlier so content vendors are not that willing to implement it, and there is not that much experience in its proper settings and behavior of parameters. So, when looking for a decent alternative to specular, Blinn is the well understood alternative of choice, especially for vendors.

my 2ct

Thatnks, Artbee.  I'd been wondering about those things too.

I've saved your last paragraph.  Nice clear direct explanation! 

Too bad the manual isn't as clear.

Thanks, I needed that.
My Missing Manuals on Material Room are in the last phase before being issued.
What a job :)

http://forum.runtimedna.com/showthread.php?44077-What-exactly-do-Diffuse-Specular-nodes-do

Quote - As a result, surfaces which face tha camera are brighter than surfaces which make a skew angle,

Lambertian surfaces which face the light source are brightest, not the camera. This is the deal with diffuse.

With specular, surfaces that face halfway between the light source and the camera are brightest.

Quote - Regular Poser diffuse as well as specular implement the "Lambert method" for this angle-dependant intensity falloff.

Not specular. Just diffuse.

http://en.wikipedia.org/wiki/Lambertian_reflectance

"Lambertian reflectance is the property that defines an ideal "matte" or diffusely reflecting surface. The apparent brightness of such a surface to an observer is the same regardless of the observer's angle of view."

Quote - Diffuse does not have other main alternatives

Actually, scatter is a much more accurate replacement for diffuse for many, many materials. Certainly for skin, scatter is king and diffuse is dead. It is the most important addition to Poser materials since Poser 5.

For rough, powdery surfaces (which includes many stone/clay type objects), clay is king.

Lifting from my 2009 thread:

A decent run-down on various specular reflection models is here.

http://en.wikipedia.org/wiki/Specular_highlight

There is a confusing nomenclature in Poser regarding "Phong". There is a Phong node, but it does not implement what is now called the Phong Reflection Model. It implements something that Mr. Phong used in the 70's which has now been discarded because computers are so much faster - we can use better models.

With some subtle differences and variation, we can make these connections:

The "Phong distribution" explained in that wikipedia article is what in Poser is called the Specular node.

The "Ward anisotropic distribution" is our Anisotropic node.

The "Cook-Torrance model" is our Blinn node. (As far as I can tell, Blinn took the Cook-Torrance model and improved upon it - resulting in the Blinn-Phong reflection model. Or something like that.)

The Glossy node is none of these. It is a clever little cheat to deal with the fact that our CG lights are effectively point sources. A point light has no dimension, and a perfect glossy specular reflection of it would have no dimension, either. The Glossy node ignores that little fact. It simulates what you'd get from a glossy surface if the light actually had some finite width to it.

More good info here:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2878324&page=3#message_4135594

An image lifted from that thread - super important - the Fresnel effect. It defines the balance between diffuse and specular for varying viewing angle.

These five surfaces have no diffuse - they are pure specular reflectors.

All were done with a combination of Blinn and Reflect nodes. (Blinn for specular reflections of Poser lights, Reflect for specular reflections of Poser props and figures.)

OP asks:

Quote - Upon examining their materials in the Materials room, I have observed that they have elements such as "Blinn" ... Can anyone shed light on how these shaders work or how they are applied, or perhaps direct me to a good tutorial?

The vast majority of the shader you see are copies of a shader I posted at runtime dna.

I did a lot of experiments and published what came to be called the S+B shader (scatter + blinn).

Then, snarlygribbly made a Poser python script called EZSkin, where he made it possible to apply my S+B shader (and some newer variations) to just about any figure and texture set with a single mouse click.

So the easiest way to make these effects is to use EZSkin.

Original article that demonstrated S+B:

http://www.runtimedna.com/forum/showthread.php?64789-Which-node-SubsurfaceSkin-or-Scatter-Blinn

A later addition was the Fresnel_Blend node and using blurred reflections (Reflect node). This was called S+B+FBR (Fresnel blended reflections). With this arrangement, it is possible to render realistic skin with no Poser lights at all.

http://www.renderosity.com/mod/gallery/full.php?image_id=2257747

http://www.runtimedna.com/forum/showthread.php?63200-SSS-on-Human-Figures&p=630590&viewfull=1

If you want to see the whole history of this start at the beginning of that thread

http://forum.runtimedna.com/showthread.php?63200-SSS-on-Human-Figures

You can get EZSkin here:

http://www.snarlygribbly.org/3d/forum/

or here:

http://www.runtimedna.com/EZSkin-2.html

Discussion of it is here:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2841324&page=1

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2845643

and here:

http://forum.runtimedna.com/showthread.php?67486-EZSkin-v1.4.3

and actually many other threads. Search for EZSkin.

Quote - > Quote - As a result, surfaces which face tha camera are brighter than surfaces which make a skew angle,

Lambertian surfaces which face the light source are brightest, not the camera. This is the deal with diffuse.

With specular, surfaces that face halfway between the light source and the camera are brightest.

which of course is a correct observation. In addition:

 * at the bottom line, specularity (aka highlights) is a trick used in various 3D software to represent the (blurred) reflections from direct light sources only. Poser reflections do not deal with direct lights themselves, and ImageBasedLigts (IBL) as well as IndirectLighting (IDL) do not produce specularity. So specularity and Reflectivity in Poser are two sides of the same coin, and you might want to balance them accordingly.
In nature, you've only got reflections of everything.

 * most advanced material setups in Poser do not export very well to external renderers or other 3D software, like Vue, Reality/LuxRender, Octane or any OBJ/MTL-like format. But as long as Poser is the end of your 3D workflow, all is well and tools like EZSkin are pretty handy indeed.

happy rendering.

bill, from what I've read, it seems like both diffuse and specular are almost pointless to use if you want anything approaching realism.  So are there any times you'd want to use them?

You mean the built-in Diffuse_Color/Value and the built-in Specular_Color/Value, which are basically the Diffuse node and the Specular node? I never use the Specular node (built-in or separate) so no to that, IMO. I always use Blinn.

For the diffuse reflection, it is a matter of roughness. If a surface does not exhibit powdery roughness like clay or the moon, then the benefit to use the Clay node isn't there, simply because when you set Clay roughness to 0, it is identical to Diffuse. In such cases, I use the Diffuse node or (rarely) the built-in Diffuse.

I use the Diffuse node, not because it's different than the built-in diffuse, but rather because I need to interpose something in front of the Diffuse node almost all the time, such as a Fresnel_Blend node.

It is possible to Fresnel_Blend the built-in diffuse, but the extra wiring involved isn't worth the effort.

If a surface exhibits subsurface scattering, then of course I use the Scatter node and not the Diffuse node (built-in or separate).

FYI if you make the scale of a Scatter node really high, it produces the same effects as a simple Diffuse node does. Scattering exists in all real life materials, but in some cases the scale is so short that it appears to happen at the surface, and so is sufficiently modeled by the traditional Lambertian reflectance equation.

In that case, using a scatter is extra computations for no benefit.