Creating realistic fur or hair seems easy in the
hands of experts but when you try it it never comes out as convincing as you want. What are they
doing that you are not? What can you do to create? stunning Hair Systems. Realism is a style choice
but one that requires a lot of attention. The goal is to convince the viewer that what they
are watching on screen isn't CGI but rather a live-action performance well today I'm going to share
with you the the key to realistic grooming using blender's hair system. This applies to hair and fur
there are two things I want to mention first. One. you would think that the modeling part doesn't
really matter for a hair system it does though. There are basic principles that apply to make the
character appealing these things will dictate the overall feel of the character and form the first
layer of detail. This will influence the third detail layer, in our case that's fur. Breaking
silhouette and adding interest and flow. For completeness sake the second layer of detail can
be medium shapes like accessories smaller objects and bits and bobs that break the silhouette.
The silhouette is important for readability of a character, these are some great example of
silhouettes. see how you can easily recognize each one? A clean silhouette is composed through the
use of shape language, rhythm and flow, contrast, stylization and proportion. Two shading. What
separates a horse from a zebra? the stripes! I know there's more but that is the main indicator
at first glance. So hair color and patterns are essential. The devil is into details, a coat of fur
is never fully one color. Even on a macro level. From a distance it might look red but closeup
you can discover a whole bunch of random hair colors In painting, we see this a lot too. The
overall feel can be a bright blue or a warm brown but upon closer examination that feeling is
composed of a different more varied color palette let's dive into grooming next! Grooming refers to
the procedure of creating and arranging elements like hair, leaves, feathers, scales and other types
of simulated fuzz on 3D models to achieve the desired look. To get a realistic coat of fur we
must find the balance between these grooming subsections density length flow variation. Let's
populate the model with a quick fur setup this way we can easily see what we're talking about.
To do so, select the model shift a to add a new curves object and from the drop down choose fur
this creates a list of geometry nodes modifiers which allows us to fully customize our hair system.
For example, in the set hair curve profile we can set the hair thickness and shape. And below that in
the interpolate hair curve section we can increase or decrease the density use the viewport amount
to reduce the interpolated hairs displayed. I will explain more about interpolation later. The density
of hair refers to how closely packed the individual strands are within a given area in real life, human
hair varies in density across different parts of the scalp. A realistic hair system should have
the right balance between the thickness and the spacing of the hair strands. In other words try
not to compensate the lack of density with the thickness of the strands. Use reference to
match the density of the desired hairstyle. Density can create the illusion of fullness or lack thereof. To
select the part where the hair should be visible we can create a density mask this can either
be done using vertex groups or Texture Maps. The first depends on the resolution of the model and
the topology the latter depends on the resolution of the texture map. In case of this Muppet we
shouldn't generate hair through the clothing A fun way to create a quick mask is to bake a
texture. What we need is the model shade it white. and the clothing around it to cast shadows .
Shade those black. We are left with a black and white mask that we can feed into our density mask texture.
To clean up the mask if needed I recommend using the texture paint capabilities of
Blender. Or use your favorite drawing program. Now this Muppet explodes out of its clothing, we should
do something about it. I think our next step will take us in the right direction. Flow refers to
the way that hair falls and moves, mimicking the natural behavior of real hair. In Blender we have
the tools to optimize flow. With our hair curves selected go into sculpt mode. On the left side we
can find our tools the most important one for this step is the comb. With the comb we can brush over
the guide curves, each guide Curve will influence a part of the total hair coverage. Whenever the
guide curves are difficult to see I recommend toggling the X-ray view here or drop down the
viewport overlays and find cage opacity down here. Use the comb to sculpt the hair in the natural
direction let it follow the arms or the legs or let it fall down the body. The 3D models aesthetics,
its overall design, will set the stage for the flow of the hair. Here I'm directing the guide
curves in a loop, almost matching yhe edge loops around the mouth. You can switch between
edit mode and sculpt mode to select individual strands. This can help when you really want to
get fine control over each strand. The interpolated curves in between two guide
curves will sort of blend from one shape to another. Think of it like keyframes and the
blending in between two poses. So by linking them up into a continuous loop we can create flow
in our fur coat. The flow of hair can be tailored to complement the wearer's facial features for
instance hairstyles that frame the face or draw attention to specific features can enhance
the overall appearance and realism. After this Muppet's first grooming pass we can clearly tell
that the hair is way too long. Hair comes, naturally, in different length but how can we control this
length in our 3D models? Well I have a couple of practical techniques to share with you firstly
we can control the length in sculpt mode using blender's hair tools. I like to use the grow and
shrink. Brush over the hairs to grow them and hold control to shrink them. This is quite useful for
human hair styles. In this case the Muppet has a fairly even hair length so why don't we use one of
Blender's hair assets to control the hair length drag the trim hair curves on the curves object.
Then play with the settings. If you combine this with the sculpting method the 'replace length'
should not be checked, but you could use this node to introduce hair length variation. For now
check the 'replace length' this will set a target length for the hair curves. When we want a bit
more control we can move this modifier to nodes using this new feature from the drop down menu,
here. a third method could be to use a texture map. I painted mine using the texture paint
tools in Blender. Now plug that into the length factor and set the range using a map range node.
Also, use a curve info node to find the surface UVS to map your texture onto the model or in
this case fur. Of course we can combine these methods. Last but not least, we need to combat the
uniformness of the generated hair system in other words we need to add variety in every way possible
that matches our reference. The quick fur operator comes with a hair curves noise already this is a
good start to break up the evenness of the coat. Remember that for most of the hair assets we can
use a vertex group or a texture map to control them and that way we can introduce variation
manually. Almost every hair curves modifier has a form of masking for example the clump hair
curves. As the name suggests this will group the interpolated hairs into smaller clusters. The
guide mask determines a factor value for the number of elgible guide curves. That means
some guide curves will be ignored for this effect. This brings me to the next effect, runaway
curves could be an excellent way to break up the uniformness of the fur coat. Add another hair
curves noise. Set the distance to a low number like 4 mm. Adjust the scale of the noise and the
scale along each curve. Now the hairs spread out quite a lot so we should limit this. Use a random
value node with the operation set to boolean. Use the probability slider to indicate we only
want a small number of hairs to be affected . The curve ID from the curve info node lets you
select the entire strand instead of each point on the strands. This is our base coat finished, but
don't be afraid to stack more hair systems on top of each other. For example this dude has some
serious overgrown ear hairs which I can more easily control now that they are a separate
curves object. For each hair system the same principles apply. Of course ear hairs are not
the only thing you can think of. We could add eyebrows, facial hair, like beards and mustaches,
or tiny hairs on the skin. To summarize we have four elements that make up a realistic grooming:
density, length, flow, and variation. The contrast between these attributes is what makes up a
believable hair system. First create a base layer then add smaller hair systems on top of that.
This will make it easier to control. Stick to these principles and you will end up with realistic
hair on your characters. There is one more thing that could help you lift your work to higher
levels. Check out this video to learn all about it. Stay creative, till next time, ciao!
