3D Topics - Edge Loops & Edge Poles
Introduction to Loops & Poles
Edge Loops
Edge Loops are exactly what the name implies. They're the loops formed by connected edges on a model.
Ideally, most "edge loops" in a model will create a full loop. But depending on "poles" and face shapes, this is not necessarily always the case for all edges in a model.
Edge loops allow easy selection in a model, allow software to use mirror modifiers properly, and to some extent, good edge loops
The quick explanation is that when we have triangles, n-gons, or even poles, it interrupts
and changes the flow of these edge loops.
AS result, triangles and n-gons are undesirable to some extent.
Meanwhile, Poles are required in a model, but should still be handled with care to make
sure our loops behave as intended.
More on that below.
Edge Poles
A Pole is a vertex that connects multiple edges.
More specifically, there are two kinds of poles, each with different properties:
N-Pole - A pole formed by 3 incoming edges.
Alternatively sometimes called "Nose Poles."
E-Pole - A pole formed by 5 incoming edges.
Alternatively sometimes called "Extrude Poles."
Poles are necessary for good topology. And yet they can create complications and mesh artefacts if not managed properly.
Having said that, it’s considered “good practice” to universally avoid poles with more than 5
incoming edges.
Poles with more than 5 incoming edges have increased likelyhood of issues such as visible pinching
and problematic deformations during animation.
As we'll see later, N-Poles and E-poles are generally expected on a model, and can be used to
route edge loops along major shapes of the model.
This edge loop routing is also referred to as
Edge Flow.
Warning About Poles
While Poles are necessary for good topology, be aware that they can still lead to problems and complications if used carelessly, particularly for deformation or subdivision.
When possible, avoid having any poles on highly visible areas that are meant to deform,
or curved areas that are meant to subdivide.
If a pole is required, attempt to manipulate the topology so you can move the pole towards
a flatter area of the model that's unlikely to deform as much.
Also reminder to generally avoid poles with more than 5 incoming edges. Those just universally tend to lead to issues.
