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CNT is a promising new material, which Wikipedia describes as such:

Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics and other fields of materials science and technology. Owing to the material's exceptional strength and stiffness, nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material.

In addition, owing to their extraordinary thermal conductivity, mechanical, and electrical properties, carbon nanotubes find applications as additives to various structural materials.

For this reason, the name carbon nanotubes appear from time to time in various works of science fiction, and I too want to use CNT in a science fiction game, set in the near future which I am making, since I am trying to achieve some degree of photorealistic graphic, I will, however, need to know what CNT will look like.

specifically, I want to know which of the two main categories of solid, non-transparent material surfaces commonly used in physically based rendering CNT would fall under.

as this article on PBR computer graphics explains,

»Electrically conductive materials, most notably metals« look quite different from other materials.

Which is why it often is sufficient to assume that the most common materials in the world are either metallic or dielectric/insulating.

Given that CNT by Wikipedia is described as:

Unlike graphene, which is a two-dimensional semimetal, carbon nanotubes are either metallic or semiconducting

I first assumed was that I should treat CNT as a metal, but I am not certain if CNT has other properties which would make it look significantly different from metal.

My question is, therefore, is it a fair approximation to render carbon nanotubes using a metallic shader? or would it be better to render it as an insulator? Edit 1: and would CNT look anisotropic.

Edit 0: So it looks like we actually already have some macroscopic CNT structures, but I really can't tell whether or not this looks metallic or not:

enter image description here

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    $\begingroup$ I think you might get a better answer on Physics. They have people who actually work with carbon nanotubes, and probably understand the optics better. $\endgroup$ – Dan Hulme Jul 14 '17 at 11:13
  • $\begingroup$ That is possibly right, in fact, I initially wanted to post it there, but thought it was too CG specific. You are however welcome to migrate the question there. $\endgroup$ – Nikolaj Jul 14 '17 at 11:15
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    $\begingroup$ I think it's actually on-topic for us, so I'm not keen to migrate it, but if other people vote to close it I will definitely migrate rather than leave it closed here. $\endgroup$ – Dan Hulme Jul 14 '17 at 12:40
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    $\begingroup$ I think "what it looks like" would depend highly on how the nanotubes are put together into a macroscopic material—like how long are the nanotubes? Are they aligned with each other, or tangled/braided, or just randomly oriented? What treatments have been done to the surface of the material, like polishing or coating, etc.? $\endgroup$ – Nathan Reed Jul 14 '17 at 21:01
  • $\begingroup$ In some configuration CNT is used for Vantablack, so it would be quite a simple shader (: $\endgroup$ – JarkkoL Jul 16 '17 at 20:36

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