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Crocodilian
03-26-2016, 03:57 PM
wonder if anyone has ever come up with a good solution for this. I'm trying to do a greenhouse with plastic sheeting, semi translucent, semi-transparent.

Quick and reasonably convincing would be preferred to very compute heavy (eg would prefer to fake it, rather than a lengthy SSS render)

Any ideas?
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Amurrell
03-26-2016, 04:11 PM
You could use the layered system and adjust the transparency and translucency to get the desired effect. Add randomization of either by using a procedural texture such as turbulence.

Quick and dirty example to maybe get started. Note: the distortion is from distorted geometry not the textures used. I decided to add some jitter for the heck of it.

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Crocodilian
03-26-2016, 04:26 PM
thank you :thumbsup" -- seems like a promising direction . . .

vector
03-27-2016, 12:19 AM
...and also use angle incidence in transparency and translucency channel

JonW
03-27-2016, 03:48 AM
This ice cube tutorial may just help, just change some of the parameters for the thickness & colour.

http://www.imagecommunications.de/tutorials/surfacethickness.html

erikals
03-27-2016, 08:15 AM
refraction blur >
http://forums.newtek.com/showthread.php?106984-paper-thin-sss-possible

http://forums.newtek.com/attachment.php?attachmentid=82786&d=1267618886

erikals
03-27-2016, 08:17 AM
sigma node >
http://forums.newtek.com/showthread.php?114462-translucent-plastic-problem&p=1096576&viewfull=1#post1096576

http://forums.newtek.com/attachment.php?attachmentid=91498&d=1294094574

jeric_synergy
03-27-2016, 12:40 PM
Very useful resource here! Saving thread....

S0nny
03-27-2016, 03:39 PM
Here a super fast setup but can work fine, and it's like 4x faster than SSS.
On the left SSS surface, on the right the fake one.

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Need some tweaks and pp, it's just a starting point but really simple to do. The noise is coming from a really low sampling shader (2) in a high dynamic range scene with no limiter, it should clean up easy with just some more samplings.

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lertola2
03-27-2016, 05:25 PM
Here a super fast setup but can work fine, and it's like 4x faster than SSS.
On the left SSS surface, on the right the fake one.

133131

Need some tweaks and pp, it's just a starting point but really simple to do. The noise is coming from a really low sampling shader (2) in a high dynamic range scene with no limiter, it should clean up easy with just some more samplings.

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That looks great. Where did you get that Schlick's Approximation node and what is its uses? I don't seem to have it.

erikals
03-27-2016, 05:42 PM
haven't used it (yet) but you can get it here...
http://wiki.db-w.com/tools/schlicks

djwaterman
03-27-2016, 07:49 PM
Awesome thread. And go get that node silly.

Crocodilian
03-28-2016, 12:29 AM
Wow . . . I really appreciate all the thinking on this, guys. So many good ideas, and its a material that I've always had to fake in Photoshop . . . but this gives me hope.

LW stands as proof that there's always more than one way to skin (and surface) a cat . . .

RebelHill
03-28-2016, 01:17 AM
Here a super fast setup but can work fine, and it's like 4x faster than SSS.

The fake looks better too... a better representation of the material... but then I spose it is in reality more of a refractive scattering effect than a diffuse scattering one.

S0nny
03-28-2016, 04:37 AM
That looks great. Where did you get that Schlick's Approximation node and what is its uses? I don't seem to have it.

Like erikals said it's on db&w website, but for any reasons you can't use it you can replace it with a lw gradient based on incident angle.

S0nny
03-28-2016, 05:00 AM
The fake looks better too... a better representation of the material... but then I spose it is in reality more of a refractive scattering effect than a diffuse scattering one.

I agree, it's a triky one. This is a roll of plastic sheet, for example
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This is one of that cases that having a real sample can make the difference in reproducing the charateristics of the material, but finding other pictures helps a lot too.