Milky White Plastic - Difficult Material Question

[joelly3d]

I have been fooling with many methods to create what I would refer to as a photo-real milky plastic. It is a milky plastic that has low refractivity. So If I were to stick a pencil in there, it doesn't blur it out. But apparently using white fog to cloud a material thickness doesn't really work which is what I was hoping would work. I tried a very low refractive value because it doesn't have refractions like glass.. but can't seem to get it right. Setting the refractions higher and keepint them blurry works for the surface look, but it also blurs what's within, and this material does not do that. I am now thinking I should revert to not using refractions and trying some more simplified look using opacity or maybe even SSS, but seems like it might be an option if made very very thin.

Attached is a small real material sample, sorry so small, it is about as much as I'm allowed to show. The physical size of the example is like 1-2CM.

I'd describe it with these properties
- Mostly clear, but has cloudiness
- White milky plastic, likely some kind of LDPE, HDPE, or acrylic.
- Shiny outer surface
- low IOR

Can anyone advise on how to achieve this type of look in VRay?

Seems some guys at keyshot are trying to figure this out too.
https://www.keyshot.com/forum/index.php?topic=1134.0

Same here, no one's come close.
http://community.foundry.com/discuss/topic/68136

[Raven]

A while back I was playing with the idea of using the volume scatter material blended with a refractive material.
It was looking very promising, but I was having issues with thinner areas not working correctly. Is more clear in the reflection and refraction elements

I was going to test it properly and report it as a bug, I just have not had the chance to revisit it. Maybe give it a try.

[joelly3d]

This is a good approach. I've honestly never used the ScatterVolume before. I think I got it pretty close using this method. Thanks for the thoughts Gavin! Trying that with the shiny coat applied with a falloff material to preserve the thin areas. Getting close.

[vandigital]

I have been fooling with many methods to create what I would refer to as a photo-real milky plastic. It is a milky plastic that has low refractivity. So If I were to stick a pencil in there, it doesn't blur it out. But apparently using white fog to cloud a material thickness doesn't really work which is what I was hoping would work. I tried a very low refractive value because it doesn't have refractions like glass.. but can't seem to get it right. Setting the refractions higher and keepint them blurry works for the surface look, but it also blurs what's within, and this material does not do that. I am now thinking I should revert to not using refractions and trying some more simplified look using opacity or maybe even SSS, but seems like it might be an option if made very very thin.

Attached is a small real material sample, sorry so small, it is about as much as I'm allowed to show. The physical size of the example is like 1-2CM.

I'd describe it with these properties
- Mostly clear, but has cloudiness
- White milky plastic, likely some kind of LDPE, HDPE, or acrylic.
- Shiny outer surface
- low IOR

Can anyone advise on how to achieve this type of look in VRay?

Seems some guys at keyshot are trying to figure this out too.
https://www.keyshot.com/forum/index.php?topic=1134.0

Same here, no one's come close.
http://community.foundry.com/discuss/topic/68136

You linked a keyshot thread from 7 years ago. They have defiantly solved that problem in keyshot 7. The cloudy plastics are really nice maybe it will give you some ideas?

[joelly3d]

Volume Scatter base with Refractive top coat works great. It's slow as all hell, but it works great.

[Raven]

Glad it worked for you Joel. Would love to see results if it's possible.

Yeah, it was slow when I tried it, I haven't checked much if there are ways of speeding it up at all.
Try lowering refraction bounces to the lowest you possibly can without getting black areas. I did a jade shader recently using this technique and that helped the speeds the most.
Also lowering your gi bounces in the volume scatter, if you can, should help.

[Art48]

Does not work with glossy reflections/refractions.

[joelly3d]

It works when layered. https://biglittlepictures.com/2018/02/16/hdpe-vray

[Art48]

Thanks for the link, I tried it but for some buggy reason glossy refractions and reflections dont get calculated in the most recent VRay build in 3ds max 2016. I tested it and sent the scene to chaosgroup and they confirmed the bug. Was testing with only two layers though - SSS and Refractive/Reflective material without fog.


Edit:
Quote from Svetlozar:
"I just discussed this issue with our leading developer and here is the conclusion.
There is a limitation with the usage of the VRayScatterVolume material when it's plugged into VRayBlendMtl as a base shader.
In order for the whole material to operate physically accurate it is necessary to use 100% white color for the coat-material blend color.
This is considered as limitation, not as a bug and a note about it will be added on the docs page for the ScatterVolumeMtl."

[FLP]

I gave it a whirl, tried a few methods (standard mtl, fast SSS, alsurface) eventually settled on this result. Standard shader but with data channel modifier driving the refraction color via vertex map.

[Art48]

Looks nice - but it is not possible with 3ds max 2016 right?

[FLP]

Looks nice - but it is not possible with 3ds max 2016 right?

Yeah, it was introduced in 2017.

[Art48]

I'm not quite sure what you mean or how that would look though. Why would you drive the "transparency" of an object using a vertexmap? How does the vertexmap look? Isn't this not physically plausible at all? Could you show me the shader setup and vertex map?

[anchovy]

It works when layered. https://biglittlepictures.com/2018/02/16/hdpe-vray

Joel- Looks like some of the images from your Tutorial are not showing up. Id be interested in seeing your setup.