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Rendering with Arnold in CINEMA 4D using the C4DtoA plug-in.
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What is the base weight I need to use when creating metal shaders? Which range are physically correct and why?

8 REPLIES 8
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Message 1 of 9
Oleg_Ronzhin
495 Views, 8 Replies

What is the base weight I need to use when creating metal shaders? Which range are physically correct and why?

 
8 REPLIES 8
Message 2 of 9
zenop
in reply to: Oleg_Ronzhin

There's metals with all kinds of appearances, and base weights can vary from near 0 to near 1. What kind of metal are you trying to reproduce?

Message 3 of 9
Oleg_Ronzhin
in reply to: Oleg_Ronzhin

Аny metal without rust and oxidation. For example, silver or aluminium

Message 4 of 9
maxtarpini
in reply to: Oleg_Ronzhin

exactly zero

Message 5 of 9
Oleg_Ronzhin
in reply to: Oleg_Ronzhin

But in the Arnold 5 metal appearance is controlled using the Base Color (facing) and Specular Color (edge tint) parameters. These are automatically translated to physical η and κ values. It means that I need to increase the value of the base weight, but what value?

Message 6 of 9
lee_griggs
in reply to: Oleg_Ronzhin

From the Base page:

"For a perfectly sharp and mirror-like reflection, increase Metalness to 1 and reduce Specular Roughness to 0. The Base Weight should also be set to 1."

Lee Griggs
Arnold rendering specialist
AUTODESK
Message 7 of 9
maxtarpini
in reply to: Oleg_Ronzhin

Oleg, base_weight is just a multiplier for your base_color. You can keep it at 1 and simply tweak the base_color alone. However what are the exact colors then for a physically based gold for example.. who knows !

You use this workflow when you are not bothered by physically correct results. Face and edge colors are translated to n and k but that doesn't mean your n, k values are correct for the metal you're trying to simulate.

I mean the model is physically based but if you don't input the correct parameter values to the model you won't have the metal you're looking for .. and while n,k have full references to any metal, colors do not afaik.

For example for gold.. n=0.27035 and k=2.7790... how would you approach that with a complexIORbyColors approach (the one you engage when tweaking with metalness).. I guess you just try to input some colors for base and edge until the material resembles something like gold.

Message 8 of 9
Oleg_Ronzhin
in reply to: Oleg_Ronzhin

Max, yes I have these colors on the base page..

Message 9 of 9
maxtarpini
in reply to: Oleg_Ronzhin

Ha I stand corrected then ! That's a bit limited as table (ie. where's titanium) but I guess you can go with that for the while.

Still don't like this 'metalness workflow' , I prefer the good old 'specular workflow' where you set base diffuse to zero and tweak your ior params and spec color.

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