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I could use some advices regarding a challenging material. As a side note I'm a pretty new blender user, switching from another 3D program. I'm ok now with the workflow and classics shaders, but this one is a bit too much for me.

So I need to render this object for a friend : picture of the transluscent plastic foam

A white half-transparent plastic foam made from small cells. I've made lots of research ant tests, with a mix of SSS, translucent, transparent shaders (with image textures) and emission shaders. Even adding some layers of polygons inside the model.

But I can't get both the glossiness, the white color, the displacement and the "depht" of the material, especially with the transparency on the edges.

This is one of my tests, quite disapointing : render and nodes

At this stage, my main option is to post-process (a lot) the render to enhance the look, but I feel I'm missing something either technically or in my way of approaching the problem. (As I said before this material is a bit too complex for me)

If anyone has an idea, critics or resources, I'm all ears.

Edit : Just adding the last render using the main suggestion : procedural volume shader + a glossy shader mixed with a transparent one with the same voronoi node. It looks way way better, almost here I think. It just needs more shininess and speculars on top, while keeping the transparency (this is the hard part), but I will do my best to fix this with the final lighting. procedural with glossy shader test

My main concern was to find a way to get the volume shader really white, but it seems ok with a little trick (using a number above 1 as color value). Alas, the render is, of course, a lot slower.

Modelising the cells with the cell fracture addons or by hands seems doable, I've made some tests for both, but way more time-consuming, as expected.

Thanks everyone, I've learned a lot.

Edit 2 : As requested, just uploaded the blend file. All credits to yann, LukeD and Duarte for the idea. I'm sure it could be perfected easely by more experienced blender users, but it has worked great for my project as it is.

I don't know if the hdri is embeded, if not I'm using one of these : http://zbyg.deviantart.com/art/HDRi-Pack-2-103458406

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    $\begingroup$ This is quite interesting question, but I fear it will never look fully realistic without actually modelling the complex cellular structure of the material. One might also be able to achieve a similar effect by faking It with volumetric materials and some sort of Voronoi texture for density control, though I wouldn't expect the same level of realism $\endgroup$ – Duarte Farrajota Ramos May 30 '17 at 13:04
  • $\begingroup$ I've never seen foamy packaging material emit any light... In my opinion there is no need for emission shaders. Try making a mix of glossy, diffuse, translucent and SS, and work on the overall lighting of the scene to enhance the properties of the material. $\endgroup$ – cegaton May 30 '17 at 13:56
  • $\begingroup$ Thanks for the comments. Duarte : your ideas are interesting and I'm going to give it a try, I'm a bit concerned about render time but I'll see. cegaton : the emission node is a little trick I stole on this topic : blenderartists.org/forum/… and it works quite well. But maybe I'm wrong and I'll see if it's a deadlock. It's great to have another point of view. $\endgroup$ – Raoultboy May 30 '17 at 14:15
  • $\begingroup$ I'm thinking use cell fracture to create the cellular structure. $\endgroup$ – PGmath May 30 '17 at 15:50
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    $\begingroup$ This one may help you: s-media-cache-ak0.pinimg.com/originals/84/9d/e5/… $\endgroup$ – Paul Gonet May 30 '17 at 16:51
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This Answer is incomplete, but might bring you closer to your goal.

testrendering of foam volume

I used a Volume shader hooked up to a voronoi texture to create the bubbles, but I didn't manage to make them glossy or refractive. Is that even possible, using volumes?

The biggest problems with your render are:

  • it is only one closed volume, it will never give realistic results
  • don't use emission shaders in non-emissive materials

With materials like this, I would strongly recommend using a completely procedural way, without any image textures.

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    $\begingroup$ It's not possible to make Volume with reflection but you can try to add a Glossy BSDF mixed with Transparent (Translucent?) by the same factor as Volume holes/cuts. Sadly it will only reflect mesh faces... $\endgroup$ – cgslav May 30 '17 at 20:54
  • $\begingroup$ Thank you so much all. I'm working on it right now and it looks really promising with an added glossy/transparent mixed shader. I will update my post later with some tests. $\endgroup$ – Raoultboy May 31 '17 at 13:46
  • $\begingroup$ @LukeD the volume with reflection is possible but in Blender Internal (you can make the volume bright without using emission). I am not a BI expert, but such option exists there. $\endgroup$ – Paul Gonet May 31 '17 at 21:01

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