Wondering which of the types of 3d modeling you should learn first? The honest answer is that the labels describe three different things: how a surface is stored, how you build it, and how an object is captured.
This guide is part of the 3d modeling basics series.
| Item | Value |
|---|---|
| Basic categories of 3D models | 2 (solid and shell) |
| Kinds of things mixed in typical type lists | 3 (representation, method, capture) |
| Building blocks of a polygon mesh | 3 (vertices, edges, faces) |
| Solid and surface models become possible | 1970s and 1980s |
| Parametric modeling becomes popular | 1990s |
These figures come from Wikipedia’s 3D modeling entry and XO3D Labs. Pages get updated, so check the sources before you rely on them.
Why the types of 3D modeling are easy to confuse
Most lists put very different ideas side by side. XO3D Labs points out that the usual list mixes three things: how a surface is described, how an artist builds it, and how an existing object is captured.
Sorting by those three questions makes the whole subject clearer:
- Representation: polygon mesh, NURBS curves and surfaces, or solid CAD.
- Method: box modeling, edge modeling, sculpting, Boolean and procedural operations.
- Capture: photogrammetry and 3D scanning of something that already exists.
If the basics are still new to you, read what is 3d modeling first and then return to this guide.
The groups also overlap. A sculpt is a mesh, a procedural system can output a mesh, and CAD is often tessellated into a mesh for rendering, so you rarely pick just one.
Solid, shell and wireframe: how a model is stored
Wikipedia says almost all 3D models fall into two categories. Solid models define the volume of an object, like a rock, and are mostly used for engineering and medical simulations.
Shell (or boundary) models describe only the surface, like a thin eggshell. Almost all visual models used in games and film are shell models, and they must be manifold, meaning no holes or cracks in the shell, to make sense as a real object.
Wireframe modeling is the skeleton approach. SelfCAD describes it as using lines, points and curves to show an object’s basic shape, often as a starting point for more detailed models.
Surface modeling begins by defining the surfaces of an object, then adjusting their size, shape and orientation. Wikipedia adds that simple wireframes were the first early 3D models, while solid and surface models arrived in the 1970s and 1980s.
Polygon modeling and box modeling
Polygonal meshes are by far the most common representation, according to Wikipedia. A mesh is made of vertices (points), edges that join them and faces that fill the space between edges.
Box modeling is one way to build that mesh. It starts from a simple primitive such as a cube and shapes it by moving, extruding, cutting and smoothing its vertices, edges and faces. SelfCAD calls it a great way for beginning modelers to learn the basics.
A simple box workflow, adapted from XO3D’s illustrative example of a small electronic housing, looks like this:
- Add a cube and scale it to the proportions of a reference drawing or photo.
- Add only the edges you need, with loop cuts where the form changes.
- Extrude or inset faces to make a raised panel, a recess or a port.
For a closer look at how this approach differs from digital clay work, see polygon modeling vs sculpting.
Your destination changes the checks. The University of Melbourne’s 3D printing guide, quoted by XO3D Labs, says a printable mesh must be closed, with an inside and an outside, and that single surfaces are not valid for printing.
NURBS, parametric CAD and sculpting
NURBS (non-uniform rational B-splines) describe curves and surfaces mathematically. McNeel, the maker of Rhino, says they can accurately represent anything from a line or circle to a free-form surface, using far less data than a faceted approximation of the same shape, as XO3D Labs reports.
Parametric CAD goes further. It builds parts from dimensions, features and constraints, so the design changes when a value changes. Wikipedia notes that parametric modeling became popular by the 1990s because designers could edit parameters instead of redrawing a model.
Sculpting suits organic shapes. Wikipedia compares manual modeling to plastic arts such as sculpting, and XO3D suggests sculpting followed by retopology where the target needs it.
Two more routes sit outside hand-built geometry. Models can also be created algorithmically (procedural modeling) or by scanning, as Wikipedia puts it. A scan records one physical object and usually needs clean-up before it is useful, according to XO3D Labs.
Which type fits your project?
Beginners often ask which type is best. The better question, per XO3D Labs, is which method fits your source material and your destination.
| You start with | Usual route |
|---|---|
| CAD or drawings | NURBS or parametric CAD, then a converted mesh |
| An organic concept | Sculpting, then retopology where needed |
| A hard-surface form | Polygon or box modeling |
| An existing object | Scanning or photogrammetry, then clean-up |
This table summarizes the routes described by XO3D Labs; many end as a polygon mesh for rendering, so check the source and what your target accepts before you rely on it.
If you are unsure, start with box modeling on a few simple objects. You will learn vertices, edges and faces, which carry over to most other methods.
Frequently asked questions
Which type of 3D modeling is best for beginners?
Show answer
SelfCAD calls box modeling a great way for beginning modelers to learn the basics of 3D modeling. It uses a simple primitive and builds up detail step by step.
Is 3D scanning the same as 3D modeling?
Show answer
Not quite. XO3D Labs notes that a scan is not the same as modeling by hand: it records one physical object and usually needs clean-up before use.
Is a sculpt different from a polygon model?
Show answer
Often the result is the same kind of object. XO3D Labs states that a sculpt is a mesh, so the difference lies mainly in how you build it.
Do I need NURBS for games and film?
Show answer
Wikipedia says almost all visual models in games and film are shell models, and polygonal meshes are by far the most common representation. NURBS and parametric CAD fit work that starts from drawings or engineering CAD.
