[C4DtoA] Hair material not working, hair renders without colour

[Andre_Thegiant]

Hi,

I am currently working on a project whereby I've decided to give the C4D's Hair system a shot. Upon my first try everything seemed to be working fine, but now all of a sudden the hair just doesn't want to work anymore.

The problem I'm facing is the following: neither Cinema's default hair material, nor Arnold's standard hair shader (with the Arnold parameters and all that jazz) are working in the IPR. No matter the change I make in the material, be it a change in Specular value or Colour value, the hair always renders without any colour (it renders gray). I'm not using any instances, only the default hair that Cinema automatically creates when you first plop the Hair object on to a geometry.

A test scene to more accurately display the problem I'm facing. As you can see, the colours just don't seem to work. This is Cinema's default hair material, but Arnold's standard hair is much the same.

The render is however successful (i.e. material changes are visible) when using Cinema's default hair material, default lights and the default Standard renderer. I've tried many things, from different lighting setups, to completely disabling the Specular value in the Hair material, I even tried switching the colour space to ACES (OCIO config) to see if that would yield any results. Sadly, nothing has worked.

It could be that I'm just missing some simple setting or something, but as it stands I'm flabbergasted as to why Arnold just decided to give up on hair when at first it worked well.

[peter.horvath6V6K3 · Accepted solution]

Only geometry related information is exported from Cinema's default Hair Material (e.g. thickness, etc.), but not the color or other shading related data.

Use a standard_hair shader and connect a ramp_rgb shader to the base color. Note, that standard_hair uses melanin to control the color from blonde to black by default. To control the hair color with a texture map, set melanin to 0.

You can also checkout the Diffuse parameter. Note: "Diffuse should not be used for realistic hair. Real hair does not have a diffuse component (unless makeup, spray, etc.). This parameter is not physically correct and is provided purely for additional artistic control. It is not needed to achieve realistic results."

[Andre_Thegiant]

Thank you Peter, I knew it had to have been a rookie mistake.