Mirror VS Plastic

[Tanner Shelton]

What is the difference between the mirror and plastic reflective shaders? And when would you use each? Since plastic has a roughness value, I'm assuming its use is much greater then just plastic, and probably more useful then mirror?

Edited December 23, 2019 by Tanner Shelton

[zoomer]

I mostly use the Glass reflection only.

AFAIK it has also a Roughness feature.

And by its additional Gray values it helps to mimic a Fresnel Effect.

Meaning, like in reality, dielectric Materials have less Reflection when

you look straight to them vs looking along their Face.

 

And our Building Materials are mostly dielectrics, very seldom pure

Metals.

 

If I want to do it more realistic if something is important, I play with

the new Metal Shader.

Where I only use the "clear coat" part for Dielectrics.

[Tanner Shelton]

Ah that makes sense. And modern PBR states that every material has a fresnel and specularity, but dielectrics just have a very minimal amount of specularity. I've been trying to figure out how to accommodate this line of thinking within Vectorworks. With the glass shader, though, are you able to use any kind of specular map? (I'm used to the roughness metal workflow)

[Tanner Shelton]

@zoomer I'm trying to use the metallic shader, but it textures my material black, I have metal reflection and roughness set to 0 and clear coat reflection set to 5 and clear coat roughness to 30 and everything else off. Color is white, how can I get it to not color my material or is this impossible and I won't be able to use an image texture for the color?

[grant_PD]

Is there anything for it to reflect?  Did you put the material in an environment (like and HDRI) where it could be reflective?

[Tanner Shelton]

It is an interior scene and has lights and other objects around it.

[grant_PD]

try this I just made a quick one.  renders fine on my computer.  

test.zip

[zoomer]

It is a purpose of a Metallic Shader to set Diffuse Color to Black.

(As Metals have no Diffuse Color, only direct Reflection)

But I think I was able to switch that behavior off somehow.

 

Has been a while but maybe this helps ?

 

 

[Tanner Shelton]

I'm trying to use the metallic shader as Zoomer suggested he does sometimes, where I use it to get a fresnel and roughness on a dielectric material for more realistic rendering. My main issue is I can set the roughness and speculiarity to what I need, and it looks great, especially with my normal map, but the actual color data from my image texture doesn't show through.

Edited December 23, 2019 by Tanner Shelton

[Tanner Shelton]

@zoomer I was actually just reading that thread during my research, I'll continue to check it out. It makes sense that it would default it to black, as is required for a PBR metal.

[zoomer]

Dielectrics have a "Diffuse" value or color.

Basically still just reflections, but in arbitrary directions as the Photons

can enter the dielectric material and get spread.

 

At least I was able to create a red plastic material with the Metallic Shader

nevertheless. Hope the screenshot in that linked post contains all necessary

settings to misuse that Shader for Dielectrics.

As I don't remember anymore what I did there.

 

But that is again a workaround that tries to work against the App.

I am in most cases very happy with the results of the Glass Reflection Shader

fake.

Or I am also very happy with many of the delivered Arroway Materials, which use

just interesting Image Textures to control Reflection amounts.

(Although there isn't any Fresnel effect at all)

Edited December 23, 2019 by zoomer

[Tanner Shelton]

I solved the issue, it required changing the color of the metal in the metallic shader to 100% black. When changing that, it no longer rendered the black diffuse and instead rendered my image texture. Rendering time didn't seem to be much longer then the glass shader as well, so might be something I will try fully on my next project for all dielectrics and see what type of impact it has on rendering time and how much it improves the overall quality of the render.

[Tanner Shelton]

@zoomer For rendering dielectrics, should I set the reflectivity low like 2%-5% and the roughness set accordingly per material? I've got a glossy coated wood I am trying to render.

[zoomer]

15 hours ago, Tanner Shelton said:

it required changing the color of the metal in the metallic shader to 100% black. When changing that, it no longer rendered the black diffuse and instead rendered my image texture.

 

I wasn't sure about that as I never tried a Texture.

Thanks,

so I know it works.

 

 

If you have Fresnel (= 100% Reflection at glancing angle) then yes.

Dielectrics have very low Reflections when you look perpendicular to a Face.

Maybe 5-8% may look better in a Rendering.

 

But if there isn't a Fresnel Feature or angle dependency, I would better go with

something like VW's Glass Shader.

In pre PBR times in 3DSMax, without such options, I was used to have unrealistic

Reflection values of 40% to mimic Glass and Plastic 🙂

 

[Tanner Shelton]

Did some tests and rendered the scene. The first is just a plastic shader with roughness and the second has every material using the metallic shader clear coat options. You can tell that the reflections are a bit more accurate with the metallic shader, but not a big enough difference to be worth the increase in rendering time. I really wish they had a reflectivity shader with roughness, reflectivity, and fresnel. So basically the glass shader but with the addition of roughness. Blurriness is okay, but setting roughness looks much more realistic I think.

 

Plastic Shader (Render time 10 minutes)

 

Metallic Shader (Render time 50 minutes)

[milezee]

@Tanner Shelton to my eye you've gained next to nothing using the Metallic Shader,  certainly not worth the effort and I'd stick with the plastic 👍