3D Modeling Fundamentals

3D Concepts: Space, Objects and Meshes

25 min

Whatever software you use (Blender, Fusion, Maya, SketchUp), 3D modelling rests on the same ideas.

3D space

Every point has X, Y and Z coordinates. Software differs on which axis points up (Blender uses Z-up; many game engines use Y-up), which matters when exporting.

Transforms

Every object has:

  • Location (where it is),
  • Rotation (how it is turned),
  • Scale (how big it is).

Transforms are relative to the object's origin (pivot point). Placing the origin sensibly (the base of a chair, the hinge of a door) makes models easier to use.

Meshes

Most 3D models are polygon meshes:

Element What it is
Vertex a point in space
Edge a line between two vertices
Face a flat surface enclosed by edges (triangle, quad or n-gon)

Every curved surface is approximated by many flat faces. More faces mean smoother shapes but heavier files.

Normals

Each face has a normal: the direction it faces. Renderers and printers use normals to know inside from outside. Flipped normals cause dark patches in renders and broken prints.

Other kinds of 3D

  • Parametric CAD (Fusion, Onshape, FreeCAD): models built from precise measurements and features; ideal for mechanical parts.
  • Sculpting (Blender sculpt mode, ZBrush): shaping millions of polygons like digital clay; ideal for organic forms.
  • NURBS/curves: mathematically smooth surfaces used in industrial design.

Choose by task: precise parts → CAD; characters and organic shapes → sculpting; general objects and games → polygon modelling.

Units and scale

Work at real-world scale from the start (metres or millimetres). Wrong scale breaks physics, lighting, AR and printing.

Check yourself

  • What is an object's origin used for?
  • What is the difference between a vertex, an edge and a face?
  • When would you choose CAD over polygon modelling?

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