What is a mesh? A mesh is a set of basic polygons (Triangles/Quads or Triangles/Quadrilateral) that are “joined” in a certain way to form the mesh itself.
If we go into more detail, we find the vertices. Vertices define the position and orientation of every single triangle of a mesh, but not only… In three-dimensional graphics, the basic geometric shape corresponds to a triangle. The triangle is the basic shape that can represent a “face” in a three-dimensional context.
A mesh is made up of several triangles and/or quadrilaterals (but also of N-Gons, polygons with more than four vertices and sides). To avoid or not… ).
The number of triangles that form a mesh determines its “resolution”, that is, it will determine if our mesh will be well rounded or angular and will have a greater or lesser number of “details”.
All forms of a mesh are approximate. In reality a circle is a set of points, as well as lines or curves. In three-dimensional models a circle (cylinder or bull etc.) is made using a series of triangles. If the number of triangles is not sufficient, it will not be possible to represent a circle (cylinder), but only its best possible approximation.
Mesh: How to make the model, basic rules
In order to make good models for printing, in addition to good software, you will have to respect some basic rules. The procedures for making your templates vary according to the type of software you choose.
If we refer to polygonal freehand modeling:
The best thing is to try to make the mesh or model using only quadrilaterals that will then be divided into triangles automatically. Using quadrilaterals during the creation of the model (mesh) facilitates its construction and prevents the occurrence of “strange artifacts” that can also be seen during modeling (and rendering).
As for the N-Gons. N-Gons may have large surfaces in the mesh, however the only way to efficiently control the shape of the mesh itself is to have many vertices or quadrilaterals (or polygons). If a surface or polygon in the mesh is very large (it has many sides) and does not have “control points”, this polygon will always be flat and cannot be otherwise.
In 3D printing you will have to check if in the slicer display there are defects generated by the presence of triangles or N-Gons. If everything seems correct you can proceed with the printing. If you notice “defects” in the print, one of the causes, could be the presence of triangles or polygons not “modeled” correctly. However, the defects generated may be so small that they are absolutely not visible.
It is therefore not wrong to find a mesh that contains quadrilaterals and triangles or N-Gons. In the following image you can see a mesh made mainly with quadrilaterals, and which contains some triangles.
Here you can see, in red, triangles, quadrilaterals, N-Gons:
Read more about Polygon mesh ( source Wikipedia )
Read More About Tris, Quads, N-Gons ( source Turbosquid )
If we refer to freehand sculpting modeling:
In order to work properly, this type of modeling needs a large number of triangles to be able to create “soft” models with a large number of details. At any time you can add “resolution” to the model and keep in mind that more detail means, a greater number of triangles and therefore more workload for your PC, as well as for your slicer later.
If you need to create a good model, with good details, keep in mind that if you print the model with a printer type FDM (deposition of molten material) too small details will still be lost. The speech changes if you decide to print the model with a printer type SLA…
Even with this modeling technique, you’ll have to avoid creating non manifold models and more generally all the errors that could compromise the quality of the mesh itself and its printing.