Metallicity vs. Glossy Reflectivity

malswansky

I'm a bit confused about the relationship between metallicity and glossy reflectivity parameters. They both seem to be able to reflect light, metallic just looks... well, more metallic. However, I've been experimenting with an ice-effect shader (Snow and Frost Shaders for Iray | Daz 3D), and at least under some conditions, high metallicity seems to reflect better than high glossy reflexivity, which I didn't expect. So I'd like to find out what is the difference between how the two function, especially when it comes to reflections?... Do they overlap at all, like is setting high metallicity somehow equivalent to setting high glossy reflectivity + an added "metal look"? Are there situations when you need to use a combination of both?

Thank you!

p.s. Also, I'm not sure if a question like this belongs to the subforum of New Users (which I am), or is it supposed to be in the Technical section, or Commons -- please let me know if I should post questions like this one elsewhere.

crosswind

Well, with Iray Uber Shader + PBR Metallicity/Roughtness mixing option, Metallicity almost overrides all other non-roughness properties except for Refraction layer ~~ Yes, high Metallicity value (esp. 1.0) is approaching to a mirror (specular) surface while Glossy Reflectivity per se cannot make such effect.

You may check this document : http://docs.daz3d.com/doku.php/public/software/dazstudio/4/referenceguide/interface/panes/surfaces/shaders/iray_uber_shader/shader_general_concepts/start

Richard Haseltine

Metallicity controls the type of material (metal vs. non-metal) which in turn affects how other properties (especially related to reflection) behave.

malswansky

Would it be fair to say that in general, glossy reflectivity is only a useful parameter for non-metallic objects, and that it doesn't really apply or do anything for objects with a relatively high metallicity values?

crosswind

malswansky said:

Would it be fair to say that in general, glossy reflectivity is only a useful parameter for non-metallic objects, and that it doesn't really apply or do anything for objects with a relatively high metallicity values?

 Yep, I think it would.

malswansky

crosswind said:

malswansky said:

Would it be fair to say that in general, glossy reflectivity is only a useful parameter for non-metallic objects, and that it doesn't really apply or do anything for objects with a relatively high metallicity values?

 Yep, I think it would.

OK, good to know! 

It's interesting that when it comes to ice, even though it's not a metal, when it comes to rendering, metallicity seems to give a more realistic representation of its reflection properties compared to glossiness (gloss reflectivity). At least in my very limited experiments and the one store-bought set of shaders that I've used.