Rendering a Head in Arnold

Responsible for all parts

As some of you may know, alongside Technical Art, I’m studying 3D modeling at San Jose State University. This double-focus has really benefited my rigging work, especially in artistic and anatomical ways. And as always, I always find my technical art knowledge coming in handy as I model.

I made a couple of discoveries in this project, most notably on how to quickly make some realistic hair. I knew about Arnold’s ability to render curves from doing rigging research, and I knew about its nice hair shader, so I set out on trying to figure out how I could make hair using that technique.

import maya.cmds as cmds
# convert hairs to renderable curves
for obj in cmds.ls(sl=1):
s = cmds.pickWalk(obj,d="down")

cmds.setAttr(s[0] + ".aiRenderCurve",1)
cmds.setAttr(s[0] + ".aiCurveWidth",.02)
cmds.connectAttr("eyebrow_shader.outColor",s[0] + ".aiCurveShader")
cmds.setAttr(s[0] + ".aiOpaque",0)

So there are a couple of attributes you have to keep in mind. Under the shape node for each curve, you have to enable it to be rendered by Arnold. You can adjust the render width of it, assign it a shader, and disable “opaque” so that it can have opacity. I wrote this quick for loop to allow me to do this to the hundreds of hairs all at once.

The only thing I don’t know how to do yet it taper and opacity fade. For now, however, this is better than anything I’ve been able to wrestle out of nHair or xGen…

The eyes have a few tricks in them too. They’re just using standard Arnold shaders, but the Cornea has Opaque disabled and its opacity (found under Refraction) turned all the way down. A high spec weight and falloff allows it to have that nice wet reflection. I drew a curve on the eyeballs (as a live surface) and used a similar technique to how I rendered the hair to give the really nice “wetness” border between the eyeball and the eyelid. I’m not sure if there’s a medical name for it, but it’s that tiny line of water… Everyone has it and it’s a really good detail to add to eyes, and with Arnold’s render curve feature it was incredibly simple to do.

The head uses a 3 layer Shallow/Mid/Deep Subsurface Scattering setup. The thing I found is the SSS will REALLY soften your features up, so if you want any hard painted attributes on your face you’re going to have to have it be really high contrast.

Besides that, good topology, lighting (I used a 3 point area light setup with an HDR sphere around it all) really helped me. I’m really excited to see where this project goes!

– Ben

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