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Thin-film Coatings are only possible in Arion Render v3.0 and better. You cannot reproduce this material in prior versions of Arion Render.

 

Start with a default Arion BSDF, set the Color and Edgetint channels to black and set Roughness to 0 .

BRDF attributes
Fresnel IOR 1.51 0.0
Falloff 46.5 16
Color
Edgetint
Roughness | % 0
Bump | % 10

 

Enable Transmittance and 1-sided.

This has the effect of making the material disappear entirely.

Transmittance
Enable
1-sided
Abbe 63.5
Atten. | cm 25
Color

 

Then enable Coatings with a Roughness of 0 or 1.

Coatings
Enable
Thin-film
Fresnel IOR 1.51
Color
Edgetint
Roughness | % 1
Thickness | nm 250 1000

 

Then enable Thin-film in the Coatings parameters.

Coatings
Enable
Thin-film
Fresnel IOR 1.51
Color
Edgetint
Roughness | % 10
Thickness | nm 250 1000
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There is a phenomenon in physics that if the thin-film coating Fresnel IOR is higher or lower than the substrate material, there is a flip in the interference colors.
This effect is handled by Arion Render. If you increase or decrease either the BRDF attributes Fresnel IOR of the Coatings Fresnel IOR, you will see the flip happening.

 

When the Coating Thin-film Thickness is not textured, only the first value is used and the Coating is then uniform (it has the same thickness everywhere).

Soap bubbles have a thin layer of soap that has varying thickness by a few hundreds of nanometer.

Arion Render can simulate this by using a grayscale image that will represent the minimum thickness (black) and maximum thickness (white).

In this example we have used an Arion Noise texture to illustrate the effect, but you can use any texture you want.

Coatings
Enable
Thin-film
Fresnel IOR 1.51
Color
Edgetint
Roughness | % 10
Thickness | nm 250 1000

 

Now the effect is subtle and heavily dependent on the nature of the light itself, the reflections of the environment. Putting this material into an HDR environment or a more complex scene will look much better.

There is a last thing we can do however to improve the intensity of the effect. The human eye only see wavelength from roughly 380nm to 750nm, so we will set our Thickness boundaries to these values.

Coatings
Enable
Thin-film
Fresnel IOR 1.51
Color
Edgetint
Roughness | % 10
Thickness | nm 380 750

 

That is it. By playing with the parameters a bit and using a better environment/lighting, you can achieve great-looking results.

 

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