Know Your UVs

A UV map is just a 3D shape laid out flat. It makes sense once you watch one fold and unfold.

Here you can take a shape apart and put it back together.

01 — The Basic Idea

You're unpacking a 3D shape onto a flat one

A term that sounds more technical than it is.

A 3D model is a hollow shape made of flat faces. Before you can paint on it, the shape gets taken apart and laid flat, the way you'd unfold a cardboard box before printing on it.

That flat layout is the UV map. Every point on the 3D surface has a matching point on the flat one, so a 2D image knows where to sit once the shape folds back into 3D.

3D shape
→
Flat layout (the UV map)

The name doesn't mean much. 3D space already uses X, Y and Z, so the flat layout borrows the next two letters.

02 — Fold And Unfold

Watch a shape flatten out

First, fold the pyramid down and see it lay out into a flat net. Then see the two common ways that shape would get cut.

Base
Face 1
Face 2
Face 3
Face 4
Watch It Unpack
Drag to rotate. Use the slider to fold it flat and watch it become a net.
Drag the shape to rotate it
100% folded (3D shape)
Two Ways To Unwrap It
The same pyramid, cut into a flat map two different ways. Both work. They just trade effort for seams.
By Hand
One connected net, so fewer cuts but more care.
Auto Unwrap
Every face becomes its own island, so it's instant but adds cuts.

By hand keeps the map to one connected piece, which comes to 4 seams. Auto Unwrap splits every face apart into 8 seams, but it's one click. Both bake down to a correct texture, so the seam count is the real trade. The pyramid on the left folds into that same connected "by hand" net, so you can see how the flat map lines up with the solid shape.

03 — When To Use Which

Fewer seams, or less effort

Both are correct. It comes down to what the surface is for.

Auto Unwrap

  • Background props, one-off objects
  • Anything not seen close up
  • Scans and photogrammetry, which are always too dense to do by hand
  • Early practice while you're learning

By Hand

  • Hero assets seen up close
  • Hand-painted textures
  • Anything getting baked (lighting, normals)
  • Text, logos, straight lines that must stay straight
  • Tight texture budgets, since fewer seams pack tighter
04 — The Advanced Bit

UDIMs: when one tile of space isn't enough

You won't need this for a while, but it's worth knowing it exists.

A UV layout (a made-up one here, not the pyramid's) usually shares one square of texture space between every shell. A UDIM setup gives each shell its own square, so every piece gets more room.

1 tile, one shared square

More tiles gives you more room for detail, but also more textures to export, name and keep track of. Worth it for a hero character. Not worth it for a background prop.