Sculpting a Baby with ZBrush for Science Illustration
The summer after my second kiddo was born, I was contracted to sculpt a ZBrush baby for a Science News magazine feature on the placenta. One of the best parts of my job is that I’m constantly learning new things. In this case, I didn’t realize that the placenta is actually the baby’s organ… not Mom’s! So it has to be pretty crafty to convince Mom’s body to let it hang around for 9 months. Gives new meaning to the alien invasion scenario! Science News fascinating article looked at the placenta’s ways of evading the Mother’s immune system. Check out their article here to learn more about the science.
For the artwork, we wanted to showcase the science of the placenta, but also get across some of the awe and wonder of life. In this post, I’ll talk a little bit about how I made the digital baby for the opening of the feature. I primarily sculpted the baby in ZBrush, and then drew the final artwork in Photoshop. Hopefully this gives some insight into how I work. To any of you just starting out with ZBrush, be warned that it’s a bit of an odd beast. It was created to be intuitive, and yet the learning curve often goes like: This makes no sense! This is NOT intuitive… and then slowly, you start figured out the basics and internalized some of the keyboard shortcuts, and oddly it DOES start to feel intuitive. GO figure…
Sculpting the Head with Dynamesh:
First, I created the shape of the head with a basic dynamesh sphere. A dyanmesh is an adaptive mesh, that allows you to 3d sculpt organically, without worrying about technical issues like mesh resolution. When you open up x symmetry is already activated, which is what we want for something like a head so that you don’t have to sculpt each eye individually.
Next, I used the inflate tool at a large size to enlarge one end to create an egg shape. Then I began sculpting the features using the standard brush and holding down ALT to indent [TIP: ALT reverses any function in Zbrush]. Since we’re sculpting a baby (a fetus technically) we want to be sure to place the facial features pretty far down the head, leaving a lot of room for the forehead. The eyes should be below the mid-point of the head – That’s what makes a baby look like a baby.
If you look closely at areas that have been pulled out, like the nose, you might notice some of the polygons beginning to stretch out. This is the beauty of dynamesh. It’s totally adaptive, so you can push and pull and sculpt intuitively. But, you may say, why are there stretched out polygons? ZBrush waits for us to tell it we’re ready for it to reassign the polygons. To do so, just hold down ctrl and drag your mouse outside the model. The polygons will be equally spread across the model and you can continue sculpting.
Cheating Fairly in Illustration
I’m all about cheating fairly, and it’s one of the things about digital art that is so fun. It’s a challenge to find the quickest, smartest way to do something. During my time in the U.C. Santa Cruz Science Illustration graduate program, a lesson that stuck with me was this:
when you’re an illustrator, as long as it’s not ripping someone else off and saves you time, it’s fair game.
As I was largely a self-taught artist before completing the UCSC program, I was amazed to learn that most professional illustrators create their art at least 30% larger than the final printed size. Working larger than final lets an artist work more quickly, since things always look tighter and more refined when shrunk down.
Cheating Fairly in ZBrush
In terms of ZBrush, it comes with a built-in ear ‘brush’ in its 3d brush palette. Although I wanted the baby to be my own creation, I don’t mind using a stock ear to speed up the process a bit. [TIP: If it doesn’t show up in your brush palette, you can click on ‘load brush’ and navigate to ZBrushes/insert/insertear2.zpr (name may differ with version or your system).] When you place it on your head, Zbrush automatically masks, or protects from editing, the rest of the head. This way, you can move and rotate the ear into the right spot (automatically placing both of them since symmetry is still on). If you need to modify the head without the ear, you can inverse the mask. Clear the mask once you’re done. Now you’re ready to re-dynamesh (ctrl+drag away from the model), and the ear is now merged with your model. You’ll want to smooth where the ear joins, and potentially add details to it so that it’s ‘your’ baby’s ear.
As great as dynamesh is, make sure you turn dynamesh off once you’re happy with the coarse features, because continuing to use dynamesh can inadvertently erase some of your details. When dynamesh smooths things out, its essentially equalizing everything out–including your carefully sculpted details! Once I started on the details of the face, I relied heavily on the crease brush for sharp details.
Creating the body with ZSpheres:
Now that I had the baby’s head, it was time to start the body. Why did I start with the head? Not for any technical reason, but I became more invested in the project and was able to better visualize the final image. To create the body I turned to zspheres. Zspheres are a quick way to create the base of organic shapes. (see this post about sculpting a wasp). Again, you’ll want to be sure that X symmetry is turned on. Each individual Zsphere can be re-sized and moved, until your proportions approximate the shape. Once this is done, you can ‘skin’ the model, to create an editable mesh ready to sculpt.
I adjusted the body and the head to ensure that the proportions were correct. Once I laid out all the major joints, I saved a copy of my model and started posing the baby into its final curled up, comfy position in the womb. Although I did sculpt the body, I didn’t spend too much time on it because I knew the focus was primarily on the placenta and the baby’s face.
Bringing it to Life in Photoshop
Finally, I finished my ZBrush sculpted baby! Well, almost. To bring it to life and show the needed details of the placenta, I needed to finish it in Photoshop. ZBrush has several built-in materials–some shiny, some soft and skin-like, others that emphasize shadows–and I like to output several of them and combine them in Photoshop. That way I can control how dark the shadows are, where I want highlights to be downplayed, and selectively play with color. This collage process helped me create the soft glowing light I was looking for. I drew the placenta in Photoshop, and I combined the baby and the placenta with more drawn details to bring it all together.
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