With the basics covered, it's time to plan out our topology.
I can generally recommend doing some amount of preparation instead of just winging it.
You will have an easier time solving this puzzle that way.
And to show how important a bit of preparation is,
I will guide you through my thought process of retopologizing the face,
one of the most complex areas in my opinion.
If you know how to tackle that, you know how
to basically retopologize almost anything.
It's also good to mention that my terminology so far and in the rest of the chapter
is pretty much a wild mix from other artists and what I came up myself.
There's no commonly agreed on terminology,
so I'll at least make sure that mine is well explained and consistent.
For the planning, I'll use the sculpt of rain after the expression tests were made
and withdraw overs from the annotation tool.
With this, we will determine the goals and minimum requirements of our topology,
especially from what we learned in chapter 3.
First off, we start with the general edge flow.
This is often the same across humanoid characters or even most animals.
There are circular loops going around the eyes,
eyelids, nose, and mouth to support the general shape.
There's also a loop going around the chin,
last line and into the nose bridge to frame the mouth and the nasal area.
The edge flow is also roughly aligned with the movement of the muscles in those areas,
not just the shapes.
Lastly, there's a loop along the jaw, ear, and temple
and then the forehead to frame the face and follow the shapes and the muscles there.
I made a separation in the middle since the other side will just be symmetrical,
so we'll just use the mirror modifier,
but this is the most basic outline that most faces will follow.
Next up, we have our landmarks.
These are areas that for specific reasons need to match a certain structure.
In this case, there are the eyebrow objects on top of the face,
which I want to match as closely as possible with the topology on the face.
This way I can be sure that the skin and the eyebrows will deform in unison.
If you would use hair simulation and grooming,
then this is probably not as important.
It's really if there are two separate objects on top of each other.
You might also have big piercings, a nasty scar with stitches, or any other landmarks,
but these are only meant to provide enough geometry to move with other objects
that are attached, not to model other objects into them.
Stitches, piercings, eyebrows, etc. should be kept
separate to not make the topology too complicated.
Following the general shapes is the first thing.
The next important thing is capturing specific surface details.
We can outline the primary creases,
which are hard edges that need to be captured by the topology.
This is usually achieved by having one or two proximity loops
next to the hard edge to keep it sharp while subdivided.
Tight to this idea are the secondary creases,
which are only becoming sharp when the area is getting compressed.
You can base these on the muscle movement and expression tests that we sculpted.
For this, there also needs to be one or two proximity loops,
but spaced out more to keep the surface smooth by default.
Only when, for example, firing off a muscle to smile
do the secondary creases become sharp by compressing the loops together.
But to make this possible, the loops need to be there and ready.
But now that we talked about the deformations of the mesh,
it's good to give an ideal structure to the areas that will articulate the most.
These are, for example, the brows, eyelids, and lips,
which can deform in various ways based on the expression.
To make the deformations as clean as possible,
there need to be at least three loops to define any arc or curvature in these areas.
What I'm talking about now is basically based
on the three-curve principle by Brian Tindal,
which I can highly recommend if you want to dive deeper into the subject.
So there need to be one mid and two end loops for each brow,
eye, and the mouth with a horizontal separation in the middle.
But just like adding curve handles will give you more control,
each of these loops should have two loops next to them.
From there on out, more loops can be added if needed
by the deformation or curvature of the surface.
But try to keep this three-curve structure
and the amount of loops symmetrical vertically and even horizontally.
The rest of the loops that go perpendicular to these articulation loops
should just be to keep the curvature of the surface intact.
For example, for the closed eyes or stretched and compressed expression,
there need to be enough loops to keep the structure of these shapes standing
and not end up with too stretched or flat surfaces.
But with all of these pieces of the puzzle, how do we connect them?
This is where the strategic placement of Poles comes in.
What we want to do with them is to redirect
these lines into square and circular patches.
The Poles should be placed away from the creases and hard edges
and instead on surfaces that stay mostly flat,
won't deform heavily or are hidden by other geometry.
With these Poles placed, we can connect the dots
and define specific patches to guide all of the
other lines in the right direction without conflicts.
So for example, by placing some Poles,
we can create a square patch inside or next to circular ones.
It's important to actually connect the Poles and not spiral them off.
This way, we have very clearly defined square and circular patches
in a constant ebb and flow next to each other and within each other.
Bringing this all together in modeling, you should end up with something like this.
I call it the patches to make the structure more clear.
But this is very much an open-ended puzzle
since there is no gold standard for retopology.
This retopology can be reused for multiple characters,
but some might need some special attention and different implementations.
For example, if you would want to add some more loops below the eyelids
and between the brows to get more definition,
you could add another circular patch like a hero mask.
If you look online at other artists' retopologies,
you will find many different solutions to the puzzle.
But as long as you understand the principles and what is needed for your character,
then you can pretty much retopologize anything.
Of course, in an actual production environment,
there is an extra chaos factor.
This planning and execution is pretty much an ideal scenario,
but there might still be some changes and last-minute adjustments,
or the time available is only very minimal.
You might want a couple more loops in the brow area
for frowning, and you add a diamond and try to hide it.
It's a bit ugly, but you can make it work.
There could also be a little graveyard below the jaw
where the arcs are just wide enough to not be too noticeable.
Also as a side note, I drew the arc the wrong way.
Loops would be coming from the face and redirected back into it.
So just to clear that up.
Extra pulse to lead some more loops into an
area where you need them is also very common.
Or some areas might lack extra pulse,
which makes the available loops a bit thin.
The better the topology, the better the animated outcome will be.
But placing more pulse comes at a cost of more stretching and pinching.
That's the tricky part of the puzzle.
In the next videos, I'll demonstrate how to retopologize the face in practice
to get to the results you see on the screen right now.