Chapter 4 refocuses on a singular task: 3D Hair. In the previous chapter we dabbled a bit with Blender’s hair tools for smaller 3d hair components, but here we’re diving deep into the more prominent 3d hair pieces.
Pretty much anytime we’re working with 3d hair, we’re dealing with tons of hairs. Hundreds of thousands if not millions. Of course it would be a nightmare trying to manage that many 3d hairs individually, so instead we can control many with a few. Parent / Guide hairs being the few that control many Children hairs.
When it comes to effective grooming, the goal becomes balancing the number of parent and child hairs. You want enough parents to adequately govern the look of the groom but not too many that it becomes cumbersome to manage. You also want to avoid too few parents where you lack adequate control over the groom while the children look unnaturally uniform.
We’re going to start with vellus hair which will quickly improve our skin’s believability. This is a hair layer that I underestimated for years...but no more. We will definitely mind vellus hair.
The vellus Blender hair layer is comprised of generic 3d hair; therefore, we don't need extreme fine tune control of this layer of hair in Blender.
Next, we’ll continue with our 3d hair and grow a beard on our digital man. From a vellus hair beard (thin and wispy) to a terminal hair beard (thick and long). I quite enjoy grooming a beard if I’m honest...maybe because I can’t grow one in real life...but they also serve as a relevant primer to scalp hair.
Scalp hair is the most complex of our Blender hair layers and I find that it has the most pressure to look right. Unless the beard is particularly glorious. The scalp groom will require all the Blender hair tools in our arsenal including selection-centric grooming, refined vertex groups for controlling 3d hair attributes, and a polished material featuring vertex color masks and procedural accents.
1. How many hairs on the human head?
Around 100,000 hairs on average. However it depends on hair color, apparently, with blondes averaging 150,000, brown-hair averaging 110,000, and redheads averaging 90,000. (According to care.getroman.com)
2. Where can I learn more about hair grooming with Blender?
3. How do I fix those black artifacts in hair follicles when using a transparent BSDF component?
I ran into this during the course and it has an easy solution: Increase the max transparent bounces in Cycles' light path settings. Default is 8 which is way too few for a head of hair. Usually by 16 or 32 it's fixed for me.
