This document discusses topology and its importance for 3D modeling and animation. It defines topology as the layout of vertices and edges in a model's wireframe. Proper topology is needed for models to deform correctly during animation. While sculpting allows organic modeling, the resulting high-poly models need retopology to be usable for animation. Retopology converts high-poly models into low-poly versions with optimized topology through a process like manually placing quads using Maya's quad draw tool directly on the high-poly model. Retopologized models are better for rigging, animation, texturing and rendering.

1. Datt 2500 Introduction
to 3D modelling
Week 08

2. Topology
Topology is how the layout of the model
(wireframe) looks and flows.
Where you place the vertices and edges in your
model forms the topology (the shape of the
edges in the wireframe)
Part of the organic modelling process is to
understand what topology is required to
animate that model properly.

3. Topology and Animation
When animating characters, the most common method
utilized is deformations. In this process, a rig is placed in
the character that the model is bound to. As the rig is
moved, the model will bend, stretch or compress to
match the rig’s position. Because of this, how a 3D
model is made can greatly affect how it animates. Two
visually identical models might look very different while
being deformed.
You will gain a better understanding of topology once
you start animating.
Mans Makinen, 2018

4. Topology Basics
-Try to model using only quads.
-Use tris sparingly (avoid them in most areas,
sometimes used in joints like the knees and elbows)
-do not use ngons (eliminate them)
-your polygons (faces) should be relatively square for
the best results with deformations (not elongated)

5. Where you need extra geometry
Even when trying to keep the polycount lower on a model,
there are some areas that need the extra geometry in order
to animate properly.
Any area of the body that will be heavily deformed (bent,
stretched or compressed) needs extra edge loops.
On a character model, these areas are the eyes, mouth,
shoulder, elbow, wrist, finger joints and knee.
When reducing polycount, it is important to reduce in areas
like the forearm that won't bend or compress.

6. Face
While we won’t really be animating the face in our
project 2, it is a good practice to try to build the head
of a model with good typology.
You want the topology to follow the muscles structure
of the face.
You need extra edge loops around the eyes and mouth
as they will deform the most.
Edge Modelling is a great way to create the key
topology of the face.

7. Edge Modelling
In edge modeling, rather than starting with a primitive shape and
refining, the model is essentially built piece by piece by placing loops of
polygonal faces along prominent contours, and then filling any gaps
between them.
Maya has some advanced tool like the quad draw tool that makes Point
and Edge Modelling significantly easier.
This technique can be efficient but you always run a higher risk of
creating non-manifold geometry or ngons if you are not careful (it is
easy to have loose vertices or edges with this technique)

8. Sculpting and
Retopoligy

9. Sculpting
In digital sculpting, meshes are created organically, using a tablet device to
mold and shape the model almost exactly like a sculptor would use rake
brushes on a real chunk of clay
Digital sculpting has taken character and creature modeling to a new level,
making the process faster, more efficient, and allowing artists to work with
high-resolution meshes containing millions of polygons
Digital sculpting is a disruptive technology in the sense that it's helped free
modelers from the painstaking constraints of topology and edge flow, and
allows them to intuitively create 3D models in a fashion very similar to sculpting
digital clay (especially with software like Zbrush)

10. Sculpting Disadvantages
While sculpting is by far the most intuitive and beginner friendly modelling
technique, there are a few disadvantages when compared to other techniques
like box modelling.
-It is great for organic shapes but not for hard surface modelling.
-to really use the sculpting tools properly you need to use very high polycount
models.
-The topology of the sculpt may not look the best when animating. Because of
this, you may need to retopologize your sculpts to make them more usable
further down the pipeline.

11. Retopology
Retopology is the process of converting higher
polycount models into lower polycount models.
It can also be used to take badly made organic models
(ngons, non-manifold geometry, bad topology, etc.) and
convert them into a model that would work better for
animation (seamless, quads, etc.)
You are basically taking your original model and
reskinning it with a lower polycount and better placed
vertices.

12. Why Retopoligize
-Complex or High Polycount models are very difficult to
rig and animate
-You can take a model with tris, ngons, non-manifold
geometry, and reskin it into simpler better built model.
-Because of this it allows you to use any modelling
method you want and get a result similar to box
modelling (all quads, even spacing between edges,
etc). You can use commands like combine and
Booleans, or high polycount sculpting or 3D scanning
and easily correct the models for use in animation later.
-Box modelling can be slow, and other methods can be
faster even when taking into account the extra time to
retopoligize them.

13. Benefits of Retopology
The extra time it takes to retopoligize the model will save you time
in the future because:
-The resulting models will be better for rigging and animating.
-The resulting models will be better for UV unwrapping and
Texturing (covered in next section of the course)
You can still use the higher polycount model to add detail back into
the lower polycount model through texturing.
You can often use the different versions of your models for different
shot types (high polycount for closeup, low polycount for wide shot).
The extra memory or processing power you save can be used to add
higher quality render effects and lighting into your animation or
game.

14. How to Retopoligize
-Some software like Zbrush has automatic tools to
retopologize your models. These are more necessary in
Zbrush because almost any model created in the software
will need to be retopoligized to be used in animation or
game engines.
-While automatic retopology is a great feature, since it is
calculated, it is not always perfect and often less than
ideal in the more complex parts of your model like the
face.
-Because of this, a lot of modellers prefer to retopoligize
their models in software like Maya because it is a fully
manual process and may increase compatibility with
other software.

15. Quad Draw Tool
-There are a few ways you can retopoligize a model in Maya but I think
the best method is the Quad Draw Tool.
-The Quad Draw tool allows you to place vertices directly on top of a
model (live model), and then connect 4 vertices into a quad.
-This is very similar to edge modelling, except much easier and faster
because you don’t have to worry about misplacing your vertices on the
z-axis as they will snap directly to the surface of the live model.
-since you control the placement of every vertex, you can quickly create
the ideal topology for animation and fully control the polycount of the
final model.
-the resulting model should be nearly identical to a model that was
painstakingly built through other methods like box modelling.

16. DO NOT SUBMIT A SCULPTED
MODEL FOR PROJECT 2 THAT
HASN’T BEEN RETOPOLIGIZED