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Iray Silk and Incidence Angle

aaráribel caađoaaráribel caađo Posts: 691
in The Commons
I used to own a great silk scarf that darkened away from the incidence angle—i.e., if you wrapped it around your hand or something, the red facing you became dark as it bent around the object. Is there anyway to simulate this in Iray? In pre-PBR times, this was done by using a gradient attached to the angle of incidence, but I don't know if that's "unbiased" and and would work with Iray. Nor, for that matter, how to put a gradient into an Iray material that reacts to the surface conditions.

Comments

  • TheKDTheKD Posts: 2,711

    Angle of incidence? It sounds like you might be talking about fresnel, but not too sure.

  • aaráribel caađoaaráribel caađo Posts: 691
    I don't know how they relate, physics-wise, but the input is kind of the same. Both look at the incidence angle, but fresnel determines reflectivity. The silk effect I'm trying to recreate might be based on micro reflections, but it's traditionally simulated by darkening the color as the angle increases.
  • TheKDTheKD Posts: 2,711

    Ugh, this would be simple to do in houdini, I am going to try a few things. I am thinking the way to do it would be in the top coat settings. Unfortunately I don't know what a lot of those settings are supposed to do lol.

  • aaráribel caađoaaráribel caađo Posts: 691
    Yeah, this is simple with most "pro" apps, where you have more exposed shader support. I don't really begrudge DAZ for keeping the nitty gritty of shader set-up from the end user, since most people will only find it baffling and error-producing. But I'd love to be able to go into an editing panel and throw in a node for this. Hopefully, there is a way, and I'm just ignorant of it. Which is often the case :)
  • TheKDTheKD Posts: 2,711
    edited July 2016

    Setting top coat layering mode as custom curve seems to have gotten me the closest.

     

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    Post edited by TheKD on
  • aaráribel caađoaaráribel caađo Posts: 691
    edited July 2016
    You can set top coat to a curve?!! How? That's excellent. In case you missed it, I'm excited :) EDIT: I just found it. Second pull-down after Top Coat Color Effect pull down for anybody reading this. Not quite as easy to use as an actual curve editor, but nice. Thanks so much!
    Post edited by aaráribel caađo on
  • TheKDTheKD Posts: 2,711
    edited July 2016
    aaráribel caađo said:
    You can set top coat to a curve?!! How? That's excellent. In case you missed it, I'm excited :) EDIT: I just found it. Second pull-down after Top Coat Color Effect pull down for anybody reading this. Not quite as easy to use as an actual curve editor, but nice. Thanks so much!

    Hope it was helpful. Also, might want to check out illume light and shader set at rendo. It's got some nice looking satin shaders, just happened to see it and thought about this thread. They kind of look like they are having the same kind of effect you describe.

    Post edited by TheKD on
  • Oso3DOso3D Posts: 15,085
    It's not quite the effect, but a dark base color and a somewhat brighter, saturated glossy color with a high roughness is close. Backacarter might also be worth poking at.
  • FistyFisty Posts: 3,416
    edited July 2016

    Backscatter is incredibly touchy.. for a one-off render where you have control of the lights it can work but it's pretty much useless as a product.

    Post edited by Fisty on
  • Oso3DOso3D Posts: 15,085

    Ah, good to know. I've had terrible results trying to use it, I thought maybe it was just me. ;)

     

  • vwranglervwrangler Posts: 4,972
    edited July 2016

    Esemwy made an iridescent silk shader freebie for Iray that might do what you need

    http://www.daz3d.com/forums/discussion/60587/iridescent-silk-iray-mdl

    It's a procedural shader, so there are channels it uses that are nonstandard. I used it in the image below which may help you know if it does what you need

    http://vwrangler.deviantart.com/art/A-is-for-Aflame-564912066 (entirely worksafe, I promise, but too big to embed)

    The dress was treated as one big material zone for that render, so the same shader was applied to the entire Merimay dress.

     

    Post edited by vwrangler on
  • Oso3DOso3D Posts: 15,085

    Another thought: high roughness glossy and THEN do regular highlights with top coat.

     

  • AllenArtAllenArt Posts: 7,175

    Rather than fresnel for top coat, you should use weighted. It works great for things that are pearly and with a sheen like velvet, silk, satin, pearls, pearly car paint, etc.

    Laurie

  • FistyFisty Posts: 3,416

    AllenArt - I love your shader presets, I have all of them living in a special place in my content. heart

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