What is a 3D model?
To understand what 3D modeling is, one must first understand what a 3D model is.
Basics
A 3D model is, to put it simply, a drawing in three dimensions. And in the context of 3D printing that is mesh models. A mesh 3D model is made up of a lot of dots (also called vertices), which are connected by lines (also called edges), which together form faces.
Uses
3D models were invented long before 3D printing existed. These are also 3D models that are used for 3D graphics – computer games and CGI for movies. Later, 3D modeling has also been used for design and construction. Now it is difficult to imagine an architect or an engineer working without 3D modeling.
3D modeling for 3D print:
But now 3D modeling is also used for 3D printing. In fact, 3D printing would not be possible without 3D modeling; it is the 3D model that tells the 3D printer what to print.
Special needs for 3D models for 3D printing
But even though it is the same kind of 3D models that are used for movies, games and 3D printing, you can not just take a 3D file from e.g. a computer game and print it on a 3D printer. In order for the 3D printer to read the model, it is important that the 3D model is topologically sane. This means, among other things, that it cannot have holes in the surface, that all its faces (or normals) must face the same way and that several volumes cannot just overlap without being joined correctly.