Understanding retopology

The way that polygons are distributed, over a model's surface is called topology. Any one model, could have lots of different topologies. Some arrangements of polygons, are useful for some situations, but not others. So far, we've used two types of topology that are good for sculpting. First, we used a box-modeled base, which allowed us to sculpt on a very even grid pattern. Then we use dynamic typology, to create extra detail right where we wanted to sculpt it. The problem is that neither of these topologies work well for animation.

In this chapter I will show you how to create a new pattern of polygons that works well for animation. So what we're looking at right now is the multi resolution sculpt that we made from a box model base. Now I want to zoom in a little bit on the head just to look at this more clearly. And actually, let's go down in the multi-resolution modifier, and decrease the previous subdivision level to 5 just make it easier to see this. So you can see that the direction, these polygons are going really doesn't have anything to do with the anatomy, or the way this would deform.

All of these edges are going against the grain of the model's structure. And if you look in a mesh that was sculpted with dyntopo, well, it's just a big mess. It's way too dense, and unstructured to animate. Blender's Retopology tools are going to allow us to build a new mesh on top of the sculpt that follows these anatomical structures and is simple enough to animate. A proper topology for animation is called a edge flow which means that the polygon edges flow in the same direction as the character's deformation. So for example you would want to have edges that kind of flowed along the eyelids and along with the different creases.

Was something kind of similar to this, and so on. Now, while it is possible to model good edge flow right from the start and bypass sculpting. I like this workflow because it gives you the greatest flexibility to experiment with sculpting before committing to edge flow. In the old days before retopology, characters took a lot longer to make, because any change to the design meant that you had to rework a lot of the polygons by hand. So for me, the best way to work is to get all the artistic sculpting done. Well, all but the fine details. And then worry about topology.

This way of working is faster, and less stressful than the old way.