In this article we’d like to give you a quick look at how our dolls are made. This will include talking about 3D modeling software, 3D printing technology and manual post-production. If we were to describe the entire process in all it’s detail it would take ages. That’s why we tried and compress the information as much as possible. And still the article turned out to be rather lengthy, so take a deep breath and bear with us.
Our 3D modeling/sculpting instrument of choice is ZBrush. Developed by Pixologic, Zbrush is an industry standard for visual effects, computer games and now dolls. Without some of it’s functions, designing dolls digitally would be much-much harder.
The Very Basics
First of a few words about 3D graphics for those of you who are unfamiliar with the subject. Every object which is drawn on the screen inside a 3D application is basically a point cloud. Each point (which is also called a vertex) is defined by 3 coordinates: X, Y and Z. That’s your basic high-school math.
Vertices are connected by lines which are called edges. Three or more edges define a polygon. A polygon is a surface which in theory can have any number of vertices, but in Zbrush we are dealing exclusively with triangles and quads (rectangular polygons). Polygons merge together to form a continuous surface of a 3D model.
By looking at this picture you can distinguish individual polygons, because they are large enough to be seen. But if you can recall watching lets say a 3D animated film, you can probably remember how smooth and natural everything looked. That’s because characters and objects in films are made of tens of millions of polygons. Models in Zbrush also tend to be very dense. The denser the mesh the more detail you can put in, but at the same time heavier models draw more computer remorses. They require faster CPUs and more memory.
It always starts with an idea. And you don’t need a computer for this. That’s why many artists prefer to think on paper, so that they can at least outline the overall direction of the project. Great thing about sketching is that you can do it anywhere anytime, as long as you have a piece of paper and something to draw with.
The Basic Sculpt
Making dolls on a computer is in some respects very different from a traditional approach. You start by defining the figure and the proportions, because it’s enormously important to make sure that designs work artistically as a whole.
We’ve been using Zbrush for a long time, and our approach evolved alone with the package itself. In early days we used Zspheres extensively to create a base mesh. Now we are using more advance tools like Dynamesh and Zremesher. It’s safe to say that without Dynamesh doll making process wouldn’t be the same, if possible at all.
If you’ve never opened Zbrush, all those terms are most likely gibberish to you. But the gist is this: sculpting with digital instruments are very much like dealing with real clay. It’s an organic and natural process once you get a hang of it. And you also get to use symmetry, which is a great time saver.
All of this is amplified by the fact that ZBrush has dozens upon dozens of different brushes, which make your creative life much easier. Clay brush, inflate brush, move brush, etc. What all this brushes do is they basically push the vertices about in 3D space to achieve certain shapes.
The Sculpting Continues
As we keep sculpting we gradually increase the density of the mesh, so that we can put in more details. In Zbrush an object typically has several levels of sub-division, and you constantly jump from one to another. Lets say, that the lowest level has 1000 polygons. If you add one sub-devision on top of that, you’ll get 4000 polys. One more means 16K and so on. Each devision multiplies the density by 4. Lower levels are used to define broad shapes, while higher sub-devision levels are for detailing.
There are certain nuances you have to consider when sculpting. One of the more general aspects of digital sculpting is that you have to be conscious of density of your mesh at all times. Some parts of the model may call for more polygons, while others don’t. And not only that but you also have to make sure that the mesh structure is as even as possible, otherwise you may get defects on the surface. Thankfully more recent tools like Zremesher help deal with such issues very quickly. What previously took several hours can now be done automatically in a few minutes.
The other thing has more to do specifically with making dolls. If your sculpt requires some very fine details, it might be a good idea to postpone it till your model is cut into pieces and the joints are more or less complete. Otherwise all those fine details will most likely be smeared by all the re-meshes which the model will have to endure.
There are great many tutorials online that will teach you how to work in Zbrush. But there’s hardly any info on how to use Zbrush to make dolls. It’s a gigantic topic and this article will not attempt cover all of it. It’s more like a theme for book. But hopefully you’ll at least get a rough idea of what it’s like to design BJD digitally.
So, we managed to make a human figure. What’s next? Here’s the todo list:
- We need to cut the figure into parts.
- Form joints using spheres and boolean* operations.
- Keep testing the joints inside the application to make sure they not only look pretty but also have the necessary functionality.
- Make the cavities as well as holes for the elastic.
- Add finer details and finishing touches.
*Boolean might not be an ideal term for this, but it's generally used to describe combining and subtracting objects.
Now the same steps in pictures
And now we proceed to make the actual joints. We do that by merging and subtracting objects. That marks the end of the easy part. Up ahead there’s a huge chunk of work, namely manual adjustments around the spherical sections. We need the surface to be perfect in order for the joint to work in the real life. Therefor we have to compensate for all the defects which might have resulted from a rather complex Boolean operations.
Different limbs might call for slightly different approaches. Right here you can see sections of the hand color-coded (it’s called polygroups) and broken into parts. Next up are the steps outlined previously: we close the holes, perform Boolean operations and test the joint.
The thickness of a socket wall is something you have to consider very carefully. It can’t be too thin since it’ll have to be printable. It might sound simple, but there many aspects to making joints which can only be fully understood through experience.
Printing and Casting
At this point you might want to ask yourself, what’s you plan of action? Are you going to print the parts and make a doll that way? Or are you preparing molds, so that your future doll will be done by casting?
Lets talk a bit about 3D printing. 3D printing today is probably among the most rapidly developing areas of technology. And there are great many way to turn a 3D file into a tangible object. Here are a few of them:
ABS: cheap technology, which can be useful. Shape is produced by layering plastic material. Unlike large factory printers ABS printers are relatively inexpensive and can be adopted for home use.
Photopolymer: slick and highly detailed. The material solidifies under UV-light. It’s more expensive and it can be fragile.
-jets (objet, multyjet, projet): solid, highly detailed and slick, but much more expensive then everything else.
Non of the materials listed above will suit your need, if you want to assemble a 3D printed doll. The trick is to get parts with holes and cavities which have to be very solid and not too slick. Slickness would mean that the joints will be slippery and the doll will be hard to pose. Right now the only plausible method for printing dolls is SLS or Selective Laser Sintering. Laser is used to melt together tiny nylon particles. The result is a very solid and silky material.
Holes, pins and cavities
Now back to our project. The inner structure of a doll is just as important as the surface. On this picture you can see how we subtract objects to make proper slots.
The end result looks something like this.
We generally try to estimate future make up in Zbrush using Polypaint function.
It might also be a good idea to try several poses before sending it for printing.
Prepare the parts for printing
You can’t print a doll as it is. First you have to separate the parts (to ensure they don’t melt together) and to position them properly. The objects are built from the bottom up, and the layers can be very noticeable if a part is not rotated correctly.
The parts arrive covered in powder. They have to be cleaned up first, and if everything is ok, it won’t take too much time to assemble the doll. If, on the other hand, something is not ok, there’s a chance that you can fix it manually but that requires special tool. SLS material is very-very sold. It’s hard to polish or to drill holes in. But the great thing about it is that it’s light, and because of it’s inherent texture the joints don’t slide.
Cleaning up, sorting and polishing parts is something that takes up most of the time. But we decided it’s better not to bore you too much with it. And the focus of this article is more shifted towards digital component of the production anyway.
In cases when the texture is not welcomed we use custom made polishing heads to remove the texture. In areas where polishing is not possible we use glossy varnish to get some smoothness.
Here are two shoulder parts: one is polished, the other is not. Diligently polished SLS has a pleasant feel to it. It can’t be damaged by water or even solvents like alcohol or acetone.
This is a very brief overview of how we go about making dolls. Keep in mind that our methods are constantly changing and evolving, and 3D printing technology progresses very rapidly. Same goes for software.
But nonetheless putting together a humanoid doll is something we’ll cover in more detail in the future.
Original article by Olga Bekreeva, English edition by Alex Yaremchuk.
Eve Studio, 2014