styrofoam / converting from Vray material

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bioman666
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styrofoam / converting from Vray material

Post by bioman666 » Thu Oct 25, 2012 4:07 am

Hi all !

I've trying to render some styrofoam pieces, and I can't make up a decent styrofoam material.

#1 - from scratch
As I understand it, SF is merely a textured and somewhat translucent plastic, so I would go for a textured-bumped (or displaced) phong mat (IOR = 1.59 according to wikipedia) and I would add some translucency or SSS...

... but all my attempts don't come even close ! Does anyone see where I'm wrong ?

#2 - converting a Vray material
I've found a pretty good looking Vray material, and I wonder if there is a way to convert it into indigo material...

I've seen some converting scripts that run into 3dMax to convert 3dmax materials <--> Vray materials, but I can't find anything similar for indigo... It must be doable since Maxigo can load Vray materials !

Anyone has reached a solution to this issue ?
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CTZn
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Re: styrofoam / converting from Vray material

Post by CTZn » Thu Oct 25, 2012 7:07 am

Use a constant (RGB) albedo to start with, the shades on the material are not realistic. The right bump value would be an extremely subtle one.
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galinette
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Re: styrofoam / converting from Vray material

Post by galinette » Thu Oct 25, 2012 10:27 am

The 1.59 IOR is for plain dense polystyren

But as a foam this makes things somewhat more complex.

I would try much lower effective IOR as a start, with low exponent, and a very subtle bump (around 1E-4 scale)

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galinette
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Re: styrofoam / converting from Vray material

Post by galinette » Thu Oct 25, 2012 11:09 am

I did a simple one here:
http://www.indigorenderer.com/materials/materials/1113

Not easy to do with SSS, as this the surface is very diffuse.
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Re: styrofoam / converting from Vray material

Post by StompinTom » Thu Oct 25, 2012 12:13 pm

galinette wrote:I did a simple one here:
http://www.indigorenderer.com/materials/materials/1113

Not easy to do with SSS, as this the surface is very diffuse.
That pretty well nails it! I was going to suggest: it looks like it's all in the bump. No obvious SSS in the Vray shader, not to my eye, anyway. The color stays consistent unless you want to accent it with a few slight imperfections. The subtle bump mapping seems to be what makes the texture come alive.

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bioman666
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Re: styrofoam / converting from Vray material

Post by bioman666 » Thu Oct 25, 2012 9:45 pm

galinette wrote:I did a simple one here:
http://www.indigorenderer.com/materials/materials/1113

Not easy to do with SSS, as this the surface is very diffuse.
:shock: That's pretty impressive ! It looks like Oren-Nayar and phong are working well provided a finely tuned bump... Again, sorry for my obsession with SSS (I did it on the ceramic material already), the magic can happen with precisely crafted "standard" materials !

Merci beaucoup Etienne ! :D

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galinette
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Re: styrofoam / converting from Vray material

Post by galinette » Thu Oct 25, 2012 11:13 pm

bioman666 wrote: :shock: That's pretty impressive ! It looks like Oren-Nayar and phong are working well provided a finely tuned bump... Again, sorry for my obsession with SSS (I did it on the ceramic material already), the magic can happen with precisely crafted "standard" materials !
I'm not 100% happy with this one though, but glad you like it!

I'm baking one with SSS right now just to try
bioman666 wrote:Merci beaucoup Etienne ! :D
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galinette
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Re: styrofoam / converting from Vray material

Post by galinette » Fri Oct 26, 2012 1:47 am

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Re: styrofoam / converting from Vray material

Post by OnoSendai » Fri Oct 26, 2012 1:53 am

Nice one Etienne.
Your material renders have a very purple tint to them though. Can you please use the default material preview scene, with all its settings?

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Re: styrofoam / converting from Vray material

Post by galinette » Fri Oct 26, 2012 4:38 am

Hi Ono,

Actually I used the default scene in Indigo, but I had to switch to linear TM and lower the gain, otherwise you could not see any texture details, the default scene being too bright for white materials.
This resulted in a greenish tint on my screen, I changed the WB to D55 which was more neutral. But my monitor being old and yellowish, it's clearly blue on a calibrated one.

The scene definitely needs some real corresponding emitter/WB definition.. This way you will have pure grays (ie R=G=B) and any tint complaint will be due to monitors only...
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