Week 2 — Topology and Asset Setup

Unit 1 Overview · Course Home · Previous: Week 1 · Next: Week 3

This week

A double session. The most useful sentence in the course, a whiteboard puzzle, the topology that
makes a muscle bulge instead of collapse — and then the Maya scene setup you will model in.

Two exercises come out of this week. Exercise 2 is the topology work.
Exercise 3 is a short take-home checkpoint on your scene setup.

Part 1 — Topology for deformation

It takes three edge loops to bend

Everything else in this section follows from this.

Fewer than three loops and the bend creases — there is nothing there to hold the form. More than
three and you are paying for detail the deformation does not use.

Remember this sentence. In Week 5 you will paint exactly this: the middle loop split between two
influences, the outer loops at 1.0 to their own joint. In Week 6 it becomes the difference between
a problem you can fix by painting and a problem you have to send back to the model.

The topology puzzle

A patch of polygons: two square faces across the top, three square faces across the
bottom, and an empty middle with no connecting edges except the border.

┌──────┬──────┐
│      │      │        two faces
├──────┴──────┤
│             │
│    solve    │        no interior edges
│             │
├─────┬───┬───┤
│     │   │   │        three faces
└─────┴───┴───┘

Your task: draw the edges in the middle without altering the top or the bottom. Every polygon
must be four-sided.

We solve this on the whiteboard before anything else. Work it alone first — the struggle is the
point.

Once solved, this is the general answer for increasing or decreasing face-loop count and for
redirecting edge loops, which covers nearly every topology problem you will hit at a shoulder,
a hip, an ear, or where a limb meets a torso.

You will also recognize it in two familiar places: it is the same topology produced when you
extrude a single polygon out of a surface, and the same configuration at the corner of a smoothed
cube.

Muscle topology

Take half a cube, open at the midpoint, and smooth it.

What you get is a dome whose boundary fits directly into an arm's edge loops, with denser
topology at the center where a muscle stretches and bulges. The four poles land at the original
cube corners — away from the center, so the region that actually deforms stays clean quads.

The same form comes from extruding a rectangular patch of polygons. When you look at the
topology around that extrusion, you should recognize the puzzle solution.

Loop patterns at the joints

Elbow, knee, shoulder, hip, wrist. Where poles are safe and where they are not.

The shoulder needs something the elbow does not: it rotates on all three axes, while the elbow
hinges on one. That difference drives how each is built and how each is weighted.

Why T-pose

Arms straight out along X, legs straight down.

This puts limb chains on axis, which means you can draw joints in orthographic views and get
predictable orientation. It also makes mirroring clean.

Part 2 — Asset setup

Registered views become aligned image planes

This is the payoff for doing Project 1 properly.

If your front, side, and back views are aligned in Photoshop and exported at the same pixel
height, they will line up in Maya's orthographic and perspective views with no further
adjustment.

The mechanism is simple: set the image plane's Height to your character's real height in
centimeters. Because the views are registered to shared guides, the same value works for all
three, and Maya derives the width from the image aspect.

If your shoulder sits forty pixels higher in the side view than in the front view, you will build
that error into the model. It is much cheaper to fix the drawing.

Building the CPEV file

MSR as a NURBS circle at the origin, with Geometry, Joints, and Controls beneath it,
created empty.

MSR
├── Geometry            ← inheritsTransform OFF
├── Joints
└── Controls

Geometry gets its inheritsTransform turned off. This is not optional, and it is worth
understanding rather than just doing.

Bound meshes are moved by their skinCluster, which calculates their position from the joints'
world matrices. If the Geometry group also inherited MSR's transform, every mesh would move
twice. Turning inheritance off is what allows the entire rest of the rig — joints, controls, IK
handles, everything — to sit inside MSR and scale together cleanly.

You will see exactly what happens if you leave it on when you get to Week 8.

Model preparation for rigging

This week
Do Exercise 2 — The Topology Puzzle, the Muscle, and the Repair · 15 points
Do (take-home) Exercise 3 — Registered Image Planes and the Asset File · 5 points
Due Project 1 — Concept, Design & Rig Spec
Start Project 2 — Character Model · due Week 3

A note on modeling time. This semester runs fifteen sessions, so there is no in-class studio
block. Your modeling happens outside class. Exercise 3 is deliberately short and due early in the
week — do it first, because everything you model afterward depends on it being right.

If your topology or your scene setup is giving you trouble, bring it to me before Week 3 rather
than after.

References

Topology

Scene setup

Next: Week 3 — Skeletons I