Skip to end of metadata
Go to start of metadata

Hair and fur shading is particular. Most engines are making use of a specific hair material to add shading properties that may be absent from the hair geometry or too long to render.

Arion Render does not provide a specific hair material, and may never do except probably for root and tip color variations.

But that doesn't mean it cannot properly render believable hair and fur, it's quite the opposite. After all, what's hair beside a transparent thin piece of geometry.

 

The model used in this tutorial was kindly provided by John Strieder.

 

It is needless to say that a proper lighting setup is more than welcome to have a realistic aspect of the hair material, like for any other material.
In this scene the setup is composed of 3 light sources and 2 large reflectors (just rough metal panes). 

 

As usual we start with a simple default Arion BSDF material.

BRDF attributes
Fresnel IOR 1.51 0.0
Falloff 46.5 16
Color
Edgetint
Roughness | % 100
Bump | % 10

 

Then select the desired color for your hair, in our case we tried a rather difficult hair color to get right: blonde.
You can check various hair colors on this handy website: www.collectedwebs.com/art/colors/hair/
 In our case we picked the Light Blonde color (RGB 230,206,168).

BRDF attributes
Fresnel IOR 1.51 0.0
Falloff 46.5 16
Color
Edgetint
Roughness | % 100
Bump | % 10

 

Hair is obviously not fully opaque, it is partially transmitting light. Although the correct way is to give it some Attenuation and Sub-Surface Scattering, this is time consuming for so many thin pieces of geometry.
For this 'fast' method, we will fake it using simple 1-sided scattering. In another tutorial we will explore the correct method.
Add some scattering using single-sheet or 1-sided scattering by turning on Transmittance, Sub-Surface Scattering and 1-sided (or single-sheet for older versions of Arion Render).

This drastically reduces our hair brightness but that's exactly what should happen.
Don't get too scare with this brightness lowering, we'll get most of it back when we will add reflections in the next step, then we will correct the color if we consider this necessary.

Transmittance
Enable
1-sided
Abbe 63.5
Atten. | cm 25
Color
Sub-Surface Scattering
Enable
1-sided
Coeff. | 1/m 4
Asym. | % 0
Color


Now we get nice shading, with partial transparency which makes the whole hair look overall better. Let's get it some reflections.
Enable Coatings reflections, using the parameters shown on the right of the render.
Basically we copy the base color to the Coatings Color channel and use a much brighter color in the Edgetint channel, in our case RGB 252,245,230.

Coatings
Enable
Thin-film
Fresnel IOR 1.51
Color
Edgetint
Roughness | % 5
Thickness | nm 250 1000

 

This gets us a nicely shaded hair, with 'anisotropic' reflections along the hair strands.
You can now decline this material's color to any other hair color, simply by changing the BRDF properties Color and the Coatings Color and Edgetint accordingly.

It is also naturally possible to use a texture as Color, where each strand will pickup the color from where it has grown.

 

Base color 'Dark Red' RGB 141,74,67Base color 'Brown' RGB 106,78,66
Base color 'White Blonde' RGB 255,245,225Base color: redhead hair photo as color texture

 

 

  • No labels