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Strange SSS/Transparency Issue

ahalsaver_b2a4b80452ahalsaver_b2a4b80452 Posts: 16
in Technical Help (nuts n bolts)

Just in the last couple days, Iray surfaces with SSS have started to show very odd chomatic artefacts when viewed through any sort of transparency- either Cutout opacity or refraction. As you can see in the portrait image, the cutout opacity on the hair cap is showing up as a reddish area, and there seems to be somethign a bit odd about the area behind the lenses.

I created a sphere with the same shader settings as the figure, but no maps and just white diffuse and glossy colors, and a translucenty of .70. I then added a flattened cube with a refaction weight of 1.0, and there is a strange amplification of the SSS color on the more distant outer rim of the sphere, while a cyan color is showing up cose to the refractive surface. 

Then I intersected the sphere with a plane primative with 0 cutout opacity, I get a cyan cast under the otherwise invisible plane.

I've tried just about everything I know how to do- changing HDR lights, parametric lights, max path length, render mode, etc.- but can't figure this out. Did nVidia drop a new driver or something? I'm stumped.

sss-cutout-opacity.jpg
865 x 865 - 288K
sss-through-refaction.jpg
865 x 865 - 108K
sss-through-zero-cutout-opacity.jpg
865 x 865 - 107K

Comments

  • crosswindcrosswind Posts: 6,986

    Tested with your cases in GR and PB but have not seen such an issue. Would you pls post the shader preset as an attachment in here?

  • ahalsaver_b2a4b80452ahalsaver_b2a4b80452 Posts: 16
    edited April 2023

    Here it is.

    duf
    duf
    sss-transp-weird.duf
    12K
    Post edited by ahalsaver_b2a4b80452 on
  • ahalsaver_b2a4b80452ahalsaver_b2a4b80452 Posts: 16
    edited April 2023

    And a new twist: my ghost lights aren't working again now. I bought new ones after the Iray transparency snafu and they worked great. Now they're not showing at all, even I applied the old fix script. This sounds more and more like a driver thing to me.

    Update: I installed the latest game-ready driver. Seems to have helped the SSS issues, but still getting weird cyan effects and still no ghost lights. I'll try dropping back to a previous driver version tonight...

    Post edited by ahalsaver_b2a4b80452 on
  • crosswindcrosswind Posts: 6,986

    Hum, probably it's a driver's issue ~ I'm using Studio Driver and found there was no problem with the above shader preset... As for ghost light, have you tried this? https://www.daz3d.com/forums/discussion/609556/creating-a-ghost-light-daz-studio-4-21-1-26#latest

  • ahalsaver_b2a4b80452ahalsaver_b2a4b80452 Posts: 16

    Got it figured out, and as usual was just something simple. I did a full render instead of just going by the viewport draw, and everything worked normally. I checked the Draw Settings tab and somehow it had got switched to Interactive instead of Photoreal. Changed to Photoreal and all my issues went away.

    Thanks for the help folks!

  • crosswindcrosswind Posts: 6,986
    edited April 2023

    OK~ Indeed, biased... Never thought of that...yes

    Post edited by crosswind on
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