Anemone Material

[babyblueboxers]

Anyone have any idea how to create an anemone material with the PBR workflow? What IOR values, sheen, refraction, subsurface scattering, etc? I've been experimenting for hours and I'm running around in circles.

[GeorgeK]

Hi,

Although my example is rather bare-bones and rough, in terms of approaching this in a PBR manner I would consider the following.
A generic  epidermal skin IOR 1.41-1.5, rough surface of 0.7, you might want to assign a gradient ramp for base color or corona distance depending on how you want the coloration to behave (preferably mapped).

Sheen is great here with a high rough amount of 0.8-1.0 depending on what you aim for and lastly for Subsurface scattering (amount 1.0 or mapped with noise to have variation) a radius of 1.5-2.5cm depending on how deep you want light to scatter, and for scatter color you can either map your base color or simply leave a neutral grey color.

I am attaching the material used on the following scene, as with everything camera work and lighting is also key here.

[cjwidd]

probably need some falloff in the emission channel to get a proper 'glow' effect; sheen helps here too.

[babyblueboxers]

Thank you so much for responding! It means a great deal to me that the Corona team takes the time to interface with its community.

I continued to experiment for many hours after posting. One thing I found in my research is that anemones actually have transparency in addition to subsurface scattering and the only way I found to achieve that was to treat the material like a glass and dial up its refractivity. This greatly increases the rendering time but provided some really gorgeous and accurate effects.

The second thing I had to recognize is that a lot of images of corals and anemones we see are from fish tanks under really bright lights. Trying to mimic these materials without consideration for the lighting was a poor decision on my part and stands in defiance of PBR principles. To remedy this, I found that a 14000 kelvin Corona Sun at 3x intensity does the trick to mimic the lighting conditions of most aquariums.

The material ended up being relatively simple. Gradient map controlling the coloring along the stalk and also piped into the Volume Absorption and Scattering slots. Refractivity at .5 and volumetric scattering distance variable depending on the translucency of the anemone in question. Subsurface scattering at 1, with a variable radius depending on the model's scale. Sheen Layer amount 1, roughness about .5, with a nice powder-blue color.

A lot of these could be tweaked to one's tastes. I hope this helps others looking to create a similar effect.

I've attached some images of my results. There's some noise because I don't have the patience for such long rendering times, but I'm satisfied with the results. :)