Comprehensive Detail: Physical Surface for P11


  • Poser Ambassadors

    Ok, I understand Poser Surface and I understand Cycles Surface root nodes. I'm a bit baffled as to the purpose and separate distinction of the Physical Surface root node. Why? And certain things I'm having trouble trying to emulate. (velvet, leather, and tactile textured shaders in Physical Surface) Could someone walk me through the purpose and functionality of this root?


  • Poser Ambassadors

    Here is a set of shaders I made with Physical Surface Root ... Some work some don't.

    0_1464047217402_Phys_Surf_test1.jpg

    Not a high resolution ... but still enough to get the idea.


  • Poser Ambassadors

    Your question prompted me to go read the manual and see what it has to say about the PhysicalSurface root node and how to decide when you want it and when you don't.

    The manual says absolutely nothing about that. The node is mentioned in a few places, but only by way of instructing the obvious (connect bump here, connect displacement here -- duh).


  • Poser Ambassadors

    So in a nutshell, here's what I think is the reason for it:

    It is meant to be a complete shader which deals with the basic Fresnel effect and basic subsurface scattering. It is meant to be able to mimic many materials without adding any additional lighting nodes. You still have to add bump or normal to finish many effects and you obviously still have to add color maps if you want modulation based on UV layout. But otherwise, you can do a lot of things without a single additional node.

    It does not do every possible shader, but it doesn't have to. That's what all the extra nodes are for.

    And for some effects (such as glass or water) it's just not set up right at all and you go to the nodes for that and use the other two root nodes.


  • Poser Ambassadors

    Another goal (although, IMO not met) is it should be possible to do a multi-material in PBR style using PBR maps alone.


  • Poser Ambassadors

    A major thing I noticed is that 3/4ths or more of the nodes come out with broken lines and thus are unusable in Physical Surface. Other issues:

    1. I can't get the SSS to work properly. (yes the numbers are all above 1)
    2. Cannot figure out how to get Jade, velvet, satin and leather out of the physical surface node. Is it not set up for that either? It is frankly still confusing. I'm glad it's not just me.
    3. It does do well for metals, but .... lacks some of the depth I've seen in yours bb.

  • Poser Ambassadors

    Your phrasing "I can't get the SSS to work properly" implies it works, just not properly. To be honest, I have not used this new feature enough to judge if it's "proper", but I'm guessing it is just an internally assembled SubsurfaceScattering (BSSRDF) node. Inasmuch as that node is proper, I'm assuming so, too, is the one built into the PhysicalSurface node. If not, it's a bug.


  • Poser Ambassadors

    @Boni said in Comprehensive Detail: Physical Surface for P11:

    1. Cannot figure out how to get Jade, velvet, satin and leather out of the physical surface node. Is it not set up for that either? It is frankly still confusing. I'm glad it's not just me.

    Jade should be possible, Velvet will not be as the diffuse reflection model embedded in PhysicalSurface is wrong for that. Leather is possible, but most leather is not a single color, nor flat, so you must add other nodes to modulate color and bump appropriately.


  • Poser Ambassadors

    @Boni said in Comprehensive Detail: Physical Surface for P11:

    1. It does do well for metals, but .... lacks some of the depth I've seen in yours bb.

    Mmm - that may be mostly that I choose the metal colors very carefully, instead of due to the node itself.


  • Poser Ambassadors

    Ok. Here I've decided to take what I learned so far ... and make jade.
    Settings:

    Diffuse: Green
    Roughness: .1
    SSS each: 40

    Light: area light, intensity: 500 distance: within 3 feet of object
    Construct: mat blackout
    Object: bb's curvytestprop

    0_1464114330629_Phys_Surf_Jade.jpg


  • Poser Ambassadors

    Next question: Can this root node do rust on metal? Or ... layers? I'm going to try some things in that area next.


  • Poser Ambassadors

    One last SSS: Strawberry Jello. Just for a giggle.

    0_1464115964088_Strawberry_Jello.jpg



  • The main purpose of the Physical Surface root is to allow for compatibility with maps out of programs like Quixel Suite and Substance Designer/Painter. Can you use nodes with it? Sure but it's really more focused on supporting maps like Albedo, Metallic, Roughness, etc. without the fuss of having to fiddle with nodes.
    0_1464117718355_1463017743183-compare-resized.png
    0_1464117726595_1463018237280-mat-resized.png

    In the images above the entire bathtub (tub, faucet, plunger, etc) is one material called bathtub. Using Substance Painter, I assign various parts of the object a material or I paint in some extra details etc. Then I export out the maps and plug them in as shown in Poser. That one material, using those four texture maps from Substance painter creates the look of multiple materials on the one object without a bunch of fancy node work to make it so. Handy for people working in games who use Poser or for folks wanting to minimize the material count in a model or just for folks not wanting to deal with nodes.


  • Poser Ambassadors

    @bagginsbill said in Comprehensive Detail: Physical Surface for P11:

    Another goal (although, IMO not met) is it should be possible to do a multi-material in PBR style using PBR maps alone.

    ^^^^^^

    I have some problems with the fidelity of the reproduction. I see weird behaviors that cause the specularity to do very non-physically based behaviors, so that is why I say "not met".


  • Poser Ambassadors

    @Teyon : Thank you so much for that clarification. We all need to know these things. This is great.

    @bagginsbill : Here is a challenge. On a separate layer I have a sand texture to roughen a rust texture. I also have clouds transparency map to separate the metal from the rust. How do I apply the bump/displacement ONLY to the designated rust areas? Another point ... How do I make the rust area on the second layer, darker? I urealize it is a secondary texture to the propriatory base layer but I'd like to see it more robust and darker.

    0_1464123662218_Rust_Test.jpg


  • Poser Ambassadors

    Rust test 2, what do you think?0_1464126958454_Rust_Test2.jpg


  • Poser Ambassadors

    Hi. Sorry I'm behind - have so much work. You're making progress on the two-layer effect and I can help improve it, but as Teyon showed, the purpose of the Physical Surface node and multi-effect maps is to produce that effect in a single layer.

    It's fine to investigate layers as a tactic for certain effects, and rust could be one of those that makes sense. However, in the context of a thread devoted to the PhysicalSurface node, this is the wrong way to go about it. Not wrong because it doesn't work, but wrong because it is non-responsive to your own question, which basically is "what is this thing for and how would I use it". Teyon showed how you use it. It doesn't involve layers.


  • Poser Ambassadors

    Here's a demonstration of (one of) the non-physical behaviors I see when using the misnamed PhysicalSurface node. (SuperFly only - I won't bother doing any demo with FireFly unless you need that for some reason)

    Here is a basic scattering material with a mildly blurred specular reflection, a skin-like pink color in the diffuse reflections, and some blood-like subsurface scattering. This isn't exactly like skin, but it isn't exactly unlike it either.

    The left-most pawn material is using my old standby Scatter + Blinn shader, connected to the legacy PoserSurface root node. I consider this to be the best, most physically correct shader that can be done with 5 or less nodes. (It is probably the one I use 99% of the time.)

    The middle pawn material is using only the PhysicalSurface root node for the entire effect.

    (We'll get to the third pawn in a minute).

    alt text

    Look at the sky reflection on the pawn head. On mine, the Fresnel effect is set correctly for a material with minimum reflection at 4% for surface pointing at the camera. The middle (PhysicalSurface) minimal reflection is way more than 4% and this is not physically correct for the material I'm trying to do. There is no way to fix it either.

    Now look at the sun reflection on the pawn shoulder. (The flat ring around the "neck")

    On my Scatter+Blinn, the sun is properly reflecting a very bright white. But on the so-called PhysicalSurface shader, the sun is unnaturally subdued. There is no physical basis for this - the reflections on this shader are wrong both in facing the camera and at a shallow angle to the camera. It does not behave with the proper Fresnel effect (first of all) and it does not let me adjust the effect properly for the material I'm trying to do. It always presents with this over-glazed look that makes everything seem like silicon. Yes you can make the Specular color darker, but then you're subduing ALL reflections, not just those facing the camera, and while you can get what some would claim is a nice effect, it's NOT PHYSICALLY CORRECT. Mine is.

    Now for added confusion, look at the third pawn on the right. This is using exactly the same PhysicalSurface shader as the middle pawn, but with one tiny change. The scattering distance is reduced to near zero.

    Mysteriously, this pawn shoulder displays the full sun reflection like it is supposed to.

    Now - I ask you - why would subscatter attenuation be a legit reason to alter the surface reflection characteristics? (Answer: it would not. This is bogus non-physical behavior.)


  • Poser Ambassadors

    Here is another render but with the environment blacked out so we only have the sun light.

    You can see that left and middle have scatter while right does not.

    You can also very clearly see how the specularity of the middle shader is very, very wrong.

    alt text

    However, while I'm pointing out flaws, I must mention the mysterious artifact I see in my favorite shader on the left pawn. The bottom corners are "lit" in a very non-physically motivated way. I surmise that there is a bug in the SubsurfaceScatter node that is NOT manifest in the PhysicalSurface.

    Very mysterious, this SuperFly. It's almost as quirky and troublesome as FireFly. It's an improvement, but still not what I expect in this decade. Sigh ...


  • Poser Ambassadors

    @bagginsbill , Wow, this is fascinating. I always had the impression that the physiscalsurface root was more for non-biological models. (inspite of Charles' example in the SmithMicro blog about SR4). I would love to see more examples on the strenghts and weaknesses of the node here as per the OP. I will however start a new thread on layering. I think there is a lot of potential there.