Chapter 2 begins by generating an optimal model from our sculpture through a process called “retopology”. Essentially this is tracing a new polygonal structure - or wireframe - over the shape of an existing model. Now if you’re wondering “well doesn’t our sculpture count as a model already?” Yes it does qualify as a 3D model but it does not qualify as an optimal model. There’s 2 main reasons we want our model to be optimal:
Since we’re trying to achieve maximum fidelity in every way with this portrait, any opportunity to optimize anything we need to take advantage of that. If we don’t, then every subsequent step in the process will suffer: If we tried to add pore-level detail to a dense sculpture, or layout UVs for it, or texture paint it, or render hair on top of it - it becomes a bottle-neck to the process that we can’t afford. If it doesn’t make Blender crash, it will certainly slow it down to the point of threatening our ability to work.
Through retopologizing our sculpture we can drastically reduce the mesh density and therefore the utility of our model. So the first half of Chapter 2 focuses on retopologizing each part of the face as well as the space in between until we have an optimal head model.
The second half of chapter 2 revolves around the second reason for optimizing our model: to sculpt high-frequency pore details.
Through chapter 1 we used dynamic topology to sculpt our head unfettered by our model’s wireframe. But dynamic topology is far less efficient when it comes to processing high polycounts, as in the millions of polygons - which we will need for pore-level detail. So essentially we need to transition from dynamic topology sculpting over to multi-resolution sculpting because it supports millions of polygons much better. This is what will enable us to sculpt extremely fine wrinkles and pores.
You could try to sculpt in the millions with dynamic topology but...your computer will not be happy. In my experience multires is the only practical way to do this with Blender (at least for now). Also since multires data is stored in a modifier, we can easily disable and enable it at will. There’s actually several power features that are unlocked because this data is housed in a modifier on top of an optimal, retopologized model.
The third...half(?)...of chapter 2 focuses on modeling everything else we will need for our portrait, like eyeballs, clothing and glasses. The eyeball is pretty simple but crucially not just a sphere. The glasses are pretty straight-forward as a hard-surface model, but the clothing gets interesting.
We’re going to model it as realistically as possible using Blender’s cloth simulation tools. It’s a technique inspired by Marvelous Designer and it might forever change the way you model clothing!
If you’re brand new to these concepts I’ve discussed in this video, I highly recommend watching the Fundamentals of 3D Mesh Modeling first.
1. Where can I learn more about Retopology?
We've taught retopology a lot through our course library. I recommend watching these courses for more info:
2. Do I have to model the same caucasian male / clothing / accessories as the course or can I pick my own?
I love to see students create unique portaits! If you're up for the challenge of applying these skills in unique ways, filling in the gaps on your own when necessary, then absolutely go for it! In fact I highly encourage it. Applying learned skills in unique ways is proof of effective education.
3. Why is my computer really laggy when sculpting in the millions of polygons?
The performance of Blender's geometric data is dependent on your hardware capabilities. Like running a high-end video game, you need equipment that can handle it. Keep in mind that we're pushing Blender hard with this project.Â
Generally I don't recommend a laptop unless it's a gaming laptop. Desktops are going to be the better option. For reference: My PC used to record this course has the following:
4. Do I need a drawing tablet to follow this course?
Technically you could use a mouse but it would be a challenge. I actually prefer a mouse for brushes like Grab and Snake hook most of the time (for more precise movements). Still a drawing tablet is highly recommended.
I can't say it's 100% required, but the pressure sensitivity and more artistically-inclined mechanics of a tablet make for far more enjoyable experience when sculpting and painting textures.
I wrote an article about tablets on our blog if you want more information.
